tag:blogger.com,1999:blog-86283252024-03-15T05:59:55.223-07:00Ambivalent EngineerAmbivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.comBlogger190125tag:blogger.com,1999:blog-8628325.post-43312789021126154912019-12-30T18:21:00.003-08:002019-12-31T01:19:00.480-08:00My own Pacifica Hybrid review<br />
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<a href="https://www.caranddriver.com/reviews/a22688297/2018-chrysler-pacifica-hybrid-reliability/">Car and Driver’s 40,000 mile 12-month long-term review ofthe Pacifica Hybrid</a> is not rosy.<span style="mso-spacerun: yes;"> </span>We’ve
put 44,000 miles on ours in 2.6 years.<span style="mso-spacerun: yes;">
</span>Why such a difference?<span style="mso-spacerun: yes;"> </span>And, what
should Chrysler change for future models?<o:p></o:p></div>
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First, C&D had a bunch of mechanical issues that we have
not had.<o:p></o:p></div>
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<ul>
<li>C&D had their hybrid battery (!) replaced under
warranty.</li>
<li>C&D had two instances of low battery coolant.<span style="mso-spacerun: yes;"> </span>Worrisome.</li>
<li>C&D had the front anti-sway-bar end links replaced under
warranty to fix a squeak.</li>
<li>C&D had a stuck cupholder which caused the center
console to be replaced under warranty.</li>
<li>C&D has had intermittent problems with the Uconnect
infotainment system.</li>
<li>One of the C&D editors reports that the vehicle at
40,000 miles “feels tired”.</li>
</ul>
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Our Pacifica has had the electronics portion of the
drivetrain, the Power Inverter Module (PIM), updated in some way at the
dealer.<span style="mso-spacerun: yes;"> </span>We have one of the first ones
built and we think Chrysler had some teething problems with these PIMs.<span style="mso-spacerun: yes;"> </span>Our windscreen was damaged by a flying rock
and was replaced, covered by insurance.<span style="mso-spacerun: yes;">
</span>That’s it.<span style="mso-spacerun: yes;"> </span>We have a lot of
confidence in the car.<o:p></o:p></div>
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I think we drive our car differently than the C&D
editors do, and I think many aspects of our usage are a lot closer to how most
people use their minivans.<span style="mso-spacerun: yes;"> </span>We drive
17,000 miles a year in California, mostly commuting, and have a level 2 charger
at home.<span style="mso-spacerun: yes;"> </span>They put on 40,000 miles,
mostly on long trips in northern states, and none of their editors have level 2
chargers at home.<span style="mso-spacerun: yes;"> </span>The colder environment
in Michigan is a significant difference more similar to most Americans and
Canadians usage.<o:p></o:p></div>
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<ul>
<li>Our battery gets a full charge every night, and expends that
charge almost every day.<span style="mso-spacerun: yes;"> </span>On school days
we drop the kids off and the car gets topped up before the trip to work.<span style="mso-spacerun: yes;"> </span>Over 2.6 years, that’s about 12,000 kWh we’ve
put into the car.<span style="mso-spacerun: yes;"> </span>My guess is that
C&D’s Pacifica got less than 1000 kWh over their trial period.<span style="mso-spacerun: yes;"> </span>Our battery has spent the majority of its
life at shirtsleeve temperatures and full charge, and their battery has spent
the majority of its life at uncomfortable temperatures, mostly cold, and empty
of charge.<span style="mso-spacerun: yes;"> </span>I’d like to know if the
battery on their vehicle is underperforming, leading to current flow limits
that are lengthening the time it takes to start the engine.<span style="mso-spacerun: yes;"> </span>Slow starts would certainly make the vehicle
feel tired.</li>
<li>Our Pacifica seems to get about 30.7 MPG when running on gas
only, such as on a long trip to southern California.<span style="mso-spacerun: yes;"> </span>C&D’s Pacifica got about the same.</li>
<li>Our car goes just over 2 miles per kWh, which is much worse
than both a Tesla and the EPA estimates.<span style="mso-spacerun: yes;">
</span>The former is due to the far more complex (and lossy) drivetrain, and
the latter… ugh.<span style="mso-spacerun: yes;"> </span>I can’t even imagine
what anyone though MPGe would be useful for.</li>
<li>We’re quite happy with 2 miles/kWh however.<span style="mso-spacerun: yes;"> </span>At $0.10/kWh, that’s 4.9 cents/mile, less
than half the 11.6 cents/mile it costs to run on $3.50/gallon gasoline.<span style="mso-spacerun: yes;"> </span>It’s not the $1600 saved that we actually
care about, but rather that we spent $1300 on electricity that mostly went to
Americans, as opposed to $2900 on gasoline that would mostly have gone to
overseas interests directly opposed to our own.<span style="mso-spacerun: yes;">
</span>We expect to drive the car for 200,000 miles and expect to save around
$12,000, which would cover the extra cost of the hybrid even without government
subsidies.</li>
</ul>
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The C&D folks complain about the noises coming from the
engine compartment.<span style="mso-spacerun: yes;"> </span>I know what this
is.<span style="mso-spacerun: yes;"> </span>When the engine is running (e.g.
it’s cold outside), as you come down to a stop you can hear one of the
motor/generators spinning faster, which is disconcerting until you understand
that the engine is going at constant RPM and is always connected to the wheels,
so the M/G is running backwards, faster, as a generator, to suck up the power
and RPMs from the engine and let the vehicle stop.<o:p></o:p></div>
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Once again I think it comes down to a difference in driving
style.<span style="mso-spacerun: yes;"> </span>When I drive the car it’s mostly
in town, where full throttle is not safe.<span style="mso-spacerun: yes;">
</span>At part-throttle operation it’s almost impossible to tell when the
engine starts, and torque response to throttle position is lightning fast, better
than my Honda S2000.<span style="mso-spacerun: yes;"> </span>My impression is
that the car is very quiet and very responsive.<o:p></o:p></div>
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C&D editors were driving around with an empty battery
and probably mashing on the throttle from stopsigns like a bunch of incompetent
teenagers.<span style="mso-spacerun: yes;"> </span>Because the engine doesn’t
run when the car is stopped, there is a transient at full-throttle takeoff
where the vehicle (a) has only half power available and (b) has to use some of
that power to start the engine.<span style="mso-spacerun: yes;"> </span>It’s not
great.<span style="mso-spacerun: yes;"> </span>I never experience this.<span style="mso-spacerun: yes;"> </span>People who want a fantastic stopped-launch
experience should get Teslas, perhaps with added noisemakers.<o:p></o:p></div>
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They also complained about there not being an EV-only option
on this car. Hello? All you have to do is stay under 75 MPH and
85 kilowatts with a battery showing any more than 0% and it’ll keep the engine
off. Sheesh. Where the hell do these people drive?<br />
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Before I get going on what I’d like to see on an updated
Pacifica, I’d like to point out how much untapped potential there is in the
drivetrain. In particular, during a full-throttle
launch to 70 mph it does not rev the engine anywhere close to maximum power. It barely gets the engine to its torque peak
at 60 mph, and as a side effect it needs only 22 kilowatts from a battery sized
to deliver 85. With an upgrade to MG A’s
inverter electronics and cooling (neither of which would require any changes
to anything else), the Pacifica could get near it’s torque peak at just 10 mph
and actually send 20 kilowatts back to the battery while doing a full
acceleration run (power generation starts to roll off just before 60 mph). That’s not helpful to the vehicle as it is,
but keep it in mind as you read the following. It’s incredible to realize that a slightly modified vehicle could deliver 105 kilowatts to… I dunno… another motor perhaps?<br />
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I should also point out that the Pacifica beats the crap out
of its battery. A Tesla P100D in
ludicrous mode will drain it’s 100 kWh battery at 582 kW, which is a rate of about
6 C. Regen charging is limited to 60 kW,
or 0.6 C, and DC charging is limited to 150 kW, or 1.5 C, and frequent use of
DC rapid charging is known to limit battery life. The Pacifica will discharge its 16 kWh
battery at 85 kW, which is 5.3 C, and regen braking sometimes gets as high as
40 kW, which is 2.5 C. These numbers
seem awfully high for a company that doesn’t have much internal expertise in batteries.<o:p></o:p></div>
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With that out of the way, let’s talk about what I’d like to see in our next Pacifica. Basically, I’d like to see Chrysler have options that put the Pacifica into direct competition with the Expedition, Suburban,
Yukon, and Sequoia, without making the basic minivan too expensive.<span style="mso-spacerun: yes;"> </span>Chrysler does not compete in
the big luxury SUV market and their hybrid can win it.<o:p></o:p></div>
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<ul>
<li>$0k: 2 inch tow hitch.<span style="mso-spacerun: yes;">
</span>It’s completely stupid the vehicle doesn’t have it standard.<span style="mso-spacerun: yes;"> </span>Fix this.</li>
<li>$4k option: 4 wheel drive.<span style="mso-spacerun: yes;">
</span>Our previous Grand Caravan had 4WD and the lack of it in the 2017
Pacifica nearly broke the deal.<span style="mso-spacerun: yes;"> </span>Electric
rear wheel drive will be a huge improvement in so many ways:</li>
<ul>
<li>Getting around in snow.<span style="mso-spacerun: yes;">
</span>Yes, even in California we visit the snow for fun, and dislike screwing
around with chains which you frequently need here if you don’t have 4WD.</li>
<li>Increased electric deceleration.<span style="mso-spacerun: yes;"> </span>I have no problem with the brake feel but I
suspect it can be made better with 4 wheel balanced regen.<span style="mso-spacerun: yes;"> </span>In particular I suspect limited traction
braking while turning will get better with balanced regen.</li>
<li>Increased efficiency, as the rear electric-only drivetrain
will be more efficient than the hybrid drivetrain up front.<span style="mso-spacerun: yes;"> </span>Also, we’ll get more regeneration, but I
think that’s a smaller effect.</li>
<li>Balanced tire wear.<span style="mso-spacerun: yes;">
</span>Because all acceleration and nearly all deceleration is handled by the
front tires, they wear excessively fast.<span style="mso-spacerun: yes;">
</span>Spreading the accel/decel loads will reduce the total wear.</li>
</ul>
<li>$6k option: Bigger battery.<span style="mso-spacerun: yes;">
</span>16 kWh means something like 11 kWh of actually usable capacity.<span style="mso-spacerun: yes;"> </span>About 56% of our mileage is driven from the
plug.<span style="mso-spacerun: yes;"> </span>(The vehicle reports a much larger
electric fraction because the engine only runs some of the time once the
battery is depleted.)<span style="mso-spacerun: yes;"> </span>A 28 kWh battery
would put an end to engine usage on most weekdays for us.<span style="mso-spacerun: yes;"> </span>The rear stow&go must stay.<span style="mso-spacerun: yes;"> </span>I just do not believe there is a packaging
problem for a 28 kWh battery, as the area under the front seats is
underutilized.</li>
<ul>
<li>The bigger battery will reduce battery wear by spreading
peak regeneration loads over more cells.<span style="mso-spacerun: yes;">
</span>Charging batteries fast is hard on them, and I’ve seen our Pacifica push
40 kW into the battery, which is a 2.5 C rate.<span style="mso-spacerun: yes;">
</span>Tesla is very aggressive with their battery but limits regen to under 1
C.<span style="mso-spacerun: yes;"> </span>Increasing to 28 kWh would reduce the
Pacifica to 1.4 C.</li>
<li>Tesla has proven that consumers will pay more for a bigger
battery.<span style="mso-spacerun: yes;"> </span>They charge $8,000 more for an
extra 12 kWh and make most of their sales with the larger batteries.<span style="mso-spacerun: yes;"> </span>I think Chrysler could charge an extra $6k
for the 16->28 kWh upgrade and see it on almost every sale.<span style="mso-spacerun: yes;"> </span>Estimates for Chrysler’s actual costs range
from $200 to $400, so $6k for an extra 12 kWh would guarantee a fat profit.<span style="mso-spacerun: yes;"> </span>The upgrade would be directly comparable to
Tesla which would score some points in the cheering section.</li>
</ul>
<li>Higher power limit on motor/generator A.<span style="mso-spacerun: yes;"> </span>Right now this thing can deliver 125 N-m of
torque, which is only used to start the engine.<span style="mso-spacerun: yes;">
</span>It is power limited to 63 kW.<span style="mso-spacerun: yes;">
</span>During full-throttle acceleration runs, during which MG A is in
generator mode the whole time, the power limit on MG A causes the computer to
run the engine slower than its maximum power peak.<span style="mso-spacerun: yes;"> </span>With a more powerful inverter and more coolant flow
(but no changes to the rotor and magnets and so on), MG A could have its power
limit increased to 110 kW.<span style="mso-spacerun: yes;"> </span>That won’t do
much on a FWD car (as there’s nowhere else to put the power), but a 4WD car can
route the extra power to the rear axle.</li>
<li>Let the driver get rid of the full-throttle stopped-launch
transient by giving him or her a way to force an engine start.<span style="mso-spacerun: yes;"> </span>This is a software change that ideally they
could roll out to existing Pacificas.<span style="mso-spacerun: yes;">
</span>Put your left foot on the brake.<span style="mso-spacerun: yes;">
</span>Floor the accelerator.<span style="mso-spacerun: yes;"> </span>The engine
should start and rev to 1500 rpm and something like 80 N*m torque.<span style="mso-spacerun: yes;"> </span>Motor/generator A will put 12 kW into the
battery and you will hear that the engine is under some load, just like if he
did this in a normal automatic.<span style="mso-spacerun: yes;"> </span>Release
the brake.<span style="mso-spacerun: yes;"> </span>Now there is no need to start
the engine while at full acceleration, so there is no transient, just constant
acceleration to 24 mph and smoothly decreasing acceleration from there to full
speed.<span style="mso-spacerun: yes;"> </span>The engine can switch to
wide-open throttle and build revs fast enough to keep A generating power, so it
should be possible to get a full-speed run even with a depleted battery.</li>
<li>$0: Ludicrous mode.<span style="mso-spacerun: yes;">
</span>Tesla has made head-snapping acceleration part of the brand of electric
cars.<span style="mso-spacerun: yes;"> </span>That’s because at anything like
legal speeds, acceleration is about torque and not power.<span style="mso-spacerun: yes;"> </span>The current Pacifica has whiners complaining
about the drivetrain, which is actually really well designed.<span style="mso-spacerun: yes;"> </span>4WD, the 28 kWh battery, and the MG A changes
are the preparation needed to utterly invert the perception of reviewers at
C&D and get Chrysler on board with Tesla fans (which are provably
legion).<span style="mso-spacerun: yes;"> </span>Frankly, the combination in a
minivan will make for very loud PR that leads to lots of sales and market
disruption.<span style="mso-spacerun: yes;"> </span>Here’s how:</li>
<ul>
<li>The existing hybrid drivetrain delivers constant
acceleration of 0.38 G until it gets power limited at 24 mph, and holds on
reasonably well to get a 7.8 second 0-60 time.<span style="mso-spacerun: yes;">
</span>Amazingly, the existing hybrid drivetrain (with software changes) needs
just 22 kW from the battery while doing this, and that’s only because of the MG
A power limits mentioned earlier.</li>
<li>The existing 16 kWh battery is limited to 85 kW output.<span style="mso-spacerun: yes;"> </span>A 28 kWh battery could put out 150 kW with
the same strain.</li>
<li>On the back axle, I want a 170 kW motor with a corner speed
of 30 mph.<span style="mso-spacerun: yes;"> </span>This is a no-screwing-around
motor but there is no deal-breaking reason not to install something this
large.<span style="mso-spacerun: yes;"> </span>It will weigh 525 pounds, just
like a Tesla’s rear unit.<span style="mso-spacerun: yes;"> </span>If there is a
problem with stow&go, increase the wheelbase a few inches to make it
fit.<span style="mso-spacerun: yes;"> </span>The standard Tesla Model X uses a
slightly higher power motor on the rear axle.<span style="mso-spacerun: yes;">
</span>With this motor the vehicle will accelerate at over 1 G off the line and
will reach 60 mph in 4 seconds, curb stomping the long-range Model X and
Porsche Cayenne S.</li>
<li>The resulting vehicle will steal most Model X sales.<span style="mso-spacerun: yes;"> </span>Ludicrous mode acceleration (2.7 sec 0-60) is
not practically achievable since it requires a much larger battery or
substantial and expensive changes to the hybrid front end.</li>
<li>I understand that any sane product manager will insist on a
derated ~80 kW rear end as an option, because you can sell the super-go-fast
stuff for an extra $20k.<span style="mso-spacerun: yes;"> </span>I’d strongly
suggest no derated version, since Chrysler really needs something disruptive to
grab a lot of electric car sales.</li>
</ul>
<li>Limited slip front differential.<span style="mso-spacerun: yes;"> </span>There is no limited slip, and both my wife
and I spin the inside right tire frequently while pulling out and turning sharp
right into traffic.<span style="mso-spacerun: yes;"> </span>We’ve obviously both
gotten sloppy about having lots of torque right off the line, but the car could
manage it better.<span style="mso-spacerun: yes;"> </span>The rear end should
have electronic limited slip since it should have one motor for each wheel.</li>
<li>Better weight distribution.<span style="mso-spacerun: yes;">
</span>I expect electric rear wheel drive and a larger batter pack to move more
weight to the back and get a better weight distribution for the common case of
1-2 adult occupants and no cargo.</li>
<li>Higher pressure tires.<span style="mso-spacerun: yes;">
</span>The hybrid weighs more than the base model and needs higher pressure
tires to handle the higher loads, especially in front.<span style="mso-spacerun: yes;"> </span>This is just a stupid oversight on Chrysler’s
part.</li>
<li>$4k option: 4 inch lift option with metal belly pans.<span style="mso-spacerun: yes;"> </span>(5.1 inch normal ground clearance, 9.0 inch
with the option.)<span style="mso-spacerun: yes;"> </span>My sister lives in the
mountains.<span style="mso-spacerun: yes;"> </span>We were talking about why she
wants a new massive SUV rather than a minivan, and it comes down to ground
clearance.<span style="mso-spacerun: yes;"> </span>She regularly has to drive
through roads that are not plowed.<span style="mso-spacerun: yes;"> </span>Snow
tires are not enough, she simply cannot have that snow pouring over the hood
and windshield.<span style="mso-spacerun: yes;"> </span>And you know that a
jacked minivan with 20 inch rims will look fantastic.<span style="mso-spacerun: yes;"> </span>For $6k, swap to air springs on all four
corners and dynamically lift the car while driving.</li>
</ul>
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<br />Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-83272044924589448122017-09-21T18:56:00.000-07:002019-08-28T19:38:26.945-07:00Elon Musk should worry about Kim Jong UnThe conventional wisdom is that, if North Korea detonates a nuclear missile near any US or allied territory, be it Guam or Seattle or Tokyo or Seoul, the US will massively retaliate: The NK air defense will be eliminated along with their offensive artillery, their naval assets sunk, their nuclear infrastructure destroyed, and most of the NK offensive capability against South Korea smashed. Even if the missile was successfully intercepted, the act of firing it would make a certain war now better for the US than an uncertain but possibly more devastating attack in the future.<br />
<br />
And, the conventional wisdom is that the North Korean government knows this, and so its nukes will not be fired as a first strike. They are a deterrent: should the regime's existence be threatened, the additional risk of invasion will seem moot, US deterrence against North Korea vanishes, and the missiles get launched. So a credible North Korean nuclear missile capability makes the stability of the North Korean regime in the interests of the US.<br />
<br />
The missile that North Korea fired over Japan failed during reentry. Packaging a nuclear weapon into a reentry vehicle is known to be difficult. It will be some time before they demonstrate reentry capability. There remains a limited amount of time, perhaps a year or two, during which North Korea will not have the capability to attack the US directly. If the US wishes to snuff out the North Korean threat before it reaches full maturity it must do so before then, and the person who will ultimately decide the US strategy is Donald Trump. Mr. Trump has convinced many international leaders that he is unpredictable.<br />
<br />
The US has attempted to punish the North Korean regime for decades with economic sanctions. These have cost the North Koreans terribly. In particular, millions may have died of starvation when their crops failed and they were unable to import food to make up shortages. Their leadership has remained undeterred and perhaps unaffected by the sanctions. The US hope and North Korean fear is that mass starvation will cause the populace to rebel against the regime and replace it with one less interested in bullying other countries.<br />
<br />
The sanctions play into the narrative that the Americans are still actively at war with North Koreans, in which they specifically target harm at ordinary people in the country. North Koreans are frequently reminded that their privations are due to American evil and that their government is actively struggling against that evil. Their bellicose actions towards South Korea and Japan are woven believably into this narrative.<br />
<br />
The logic that prevents North Korea from using its nuclear weapons relies on the assumption that the thing that is threatened (the lives of many American or presumably South Korean or Japanese citizens) is so valuable to people in the US that they are willing to risk the lives of millions of their own and allied citizen to secure against that threat. North Korea has repeatedly demonstrated, however, that the US will not respond massively to attacks which cause little or no loss of life.<br />
<br />
In 2010, North Korea torpedoed and sank a South Korean military ship, killing 46 crew members. Later that year, they shelled a South Korean island, killing four. In 1987, North Korean agents blew up a South Korean airliner, killing 115 aboard. None of these actions provoked a military response from the US or South Korea.<br />
<br />
In 2014, North Korean hackers stole internal information from Sony Pictures Entertainment, and then used a combination of blackmail with that information and direct terrorist threats to cause Sony to stop the theatrical release of a movie critical of the North Korean regime. Sony set aside $15m to cover associated direct damage and lost any money that might have been made on the film. The next year, New Regency cancelled production of another movie critical of North Korea.<br />
<br />
On July 9, 1962, the US detonated a 1.4 megaton thermonuclear bomb 250 miles above Johnson island and 900 miles from Hawaii. Because the bomb was above the atmosphere, there was no blast damage at ground level. However, the electromagnet pulse from the bomb blew out 300 street lights in Honolulu and damaged the Kauai'i microwave link, severing phone communication to the island. The beta particles (high speed electrons) from the bomb, which would be converted into simple heat in an airburst, instead formed radiation belts around the Earth that disabled three satellites and lasted five years.<br />
<br />
Many of the effects had been predicted, but still came as a shock to some in the military. Long-lived degradation of the Low Earth Orbit environment was not in the interests of either of the superpowers at the time. The US and USSR signed the Partial Test Ban Treaty the next year, ending exoatmospheric nuclear tests by the two.<br />
<br />
North Korea is the first ICBM-armed nation that does NOT have orbital infrastructure. That makes asymmetrical nuclear warfare possible. During the next few years when their deterrent appears inevitable but is not yet mature, North Korea has the capability to detonate a nuclear weapon just above the atmosphere.<br />
<br />
<ul>
<li>If the weapon can be detonated within 80 km of a satellite, that satellite can be directly killed. Possible targets include the three US KH-12 optical spy satellites currently in orbit, which North Korea could excuse as being legitimate military targets, actively engaged against it, of a state it is currently at war with. There is no production line for those satellites. If they are lost, it will take years to replace them.</li>
<li>The Low Earth Orbit radiation environment can be made substantially more adverse. It is possible to make satellites survive these conditions: the GPS satellites currently orbit partially within the Van Allen radiation belts and are specially hardened to tolerate those conditions. Geosynchronous and Low Earth Orbit satellites have not generally been built that robust. In particular, the $100 billion International Space Station is in Low Earth Orbit and is unable to protect its occupants from increased radiation. A North Korean detonation could cause the astronauts to evacuate and permanently abandon the ISS.</li>
<li>The weapon could be detonated over the Sea of Japan between Japan and South Korea, for instance, a bit north of Tsushima. It would appear to be just another demonstration until the moment of detonation. A single detonation could damage millions of vehicles in both countries without directly killing anyone and without causing similar damage in North Korea or significant fallout. The resulting logistical problem would cost many billions of dollars to fix.</li>
</ul>
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This is all so expensive that I think it sufficiently deters the US from initiating a strike on North Korea right now. The window for snuffing out the North Korean nuclear threat has closed.</div>
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<div>
Once the North Koreans have a credible re-entry vehicle, however, a new window opens. It's not clear that the US would be willing to go to war and risk an actual nuclear ground strike in response to an North Korean EMP strike. So that means North Korea can demonstrate an EMP strike and use the threat of a larger EMP strike to extort the US and its allies for billions of dollars a year.</div>
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<div>
To bring all this around to the clickbait title of this post, I'm concerned that the consequence of those demonstrations is that Low Earth Orbit is going to become uninhabitable in the next few years. That's going to put a serious crimp in Elon Musk's plans to launch people to the ISS and eventually elsewhere. So maybe our real life Tony Stark can figure out some way to fix North Korea.</div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-7202356514428325022015-04-14T15:49:00.000-07:002015-06-01T10:47:23.868-07:00Vegetarians use... similar waterThe Los Angeles Times has the best tool that I've yet seen for understanding the amount of water used in agriculture. It lets you put together various proteins, starches, vegetables, and drinks to make a typical dinner, and shows you how much water it takes to produce all those things. <a href="http://graphics.latimes.com/food-water-footprint/">Check it out.</a><br />
<br />
The lowest water-use dinner I could come up with took 135 gallons of water to deliver two eggs, carrots, potatoes, and a glass of beer. Most dinners are vastly more than that. The biggest takeaway here is that each person in my family of five uses more water in the food we eat than we use together for the house and back yard.<br />
<br />
[Edit: unfortunately, the LA Times article has a serious error, which I made as well in my original version of this post. They confounded the dry and as-eaten (boiled) weights of peas, lentils, and chickpeas. This leads to a very large overestimation of the water used per protein delivered. I have corrected this error in the content and tables below. Big thanks to Miciah Masters for finding the problem!]<br />
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The biggest consumers of water are all proteins: beef, lamb, and pork. For most meals the protein consumes way more than half of all the water. I was quite surprised to see that chicken eggs and meat, and goat meat, are about as efficient as vegetarian stables like peas, soy, chickpeas, and lentils.<br />
<br />
Arjen Hoekstra, the founder of Water Footprint Network, has spent years researching agricultural water use. One of his messages is that "<a href="http://waterfootprint.org/en/water-footprint/personal-water-footprint/">animal products demand</a> considerably higher amounts of water than do most other food types." (Quote of Mr. Hoekstra from LA Times.) This makes intuitive sense, because animals consume and do not produce protein and carbohydrates. If you ate the stuff that the animal eats instead, that would have to be a more efficient way to get those proteins and calories than by eating the animal.<br />
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But people, even vegetarians, <u>don't</u> eat the stuff we feed animals. We feed animals cheap vegetables (like grass and grains and corn mash left over from making ethanol), and eat the expensive ones (like carrots and blueberries) ourselves. Mr. Hoekstra is correct that many animal products demand more water than vegetarian products. But that's not true of poultry in particular, and it's important to note that <a href="http://www.huffingtonpost.com/2014/01/02/chicken-vs-beef_n_4525366.html">chicken is more popular in the U.S. than beef</a>.<br />
<br />
This is great news, of course, since it's far easier for most people to eat more chicken and less beef, than it is for them to switch to a vegetarian diet. It does somewhat skewer Mr. Hoekstra's underlying goal of motivating vegetarianism, but of course that's the danger of working with real data.<br />
<br />
So here's my analysis. The water usage that the LA Times quotes are for an 8 ounce serving of all the various protein-rich foods. As you might expect, beef has a lot more protein in it than the same amount of lentils. If I correct the serving size to get the same amount of protein in all servings, the ranking comes out like this, from best to worst:<br />
<br />
<table>
<tbody>
<tr><th>Food</th><th width="10"></th><th>Serving Size</th><th width="10"></th><th>Protein content</th><th width="10"></th><th>Fat content</th><th width="10"></th><th>Carb content</th><th width="10"></th><th>Water Used</th></tr>
<tr><td>Peas</td><td></td><td>36 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>4 g (38 cal)</td><td></td><td>147 g (588 cal)</td><td></td><td>112 gallons</td></tr>
<tr><td>Chicken</td><td></td><td>8 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>29 g (259 cal)</td><td></td><td>0 g (0 cal)</td><td></td><td>131 gallons</td></tr>
<tr><td>Eggs</td><td></td><td>16 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>47 g (420 cal)</td><td></td><td>6 g (22 cal)</td><td></td><td>193 gallons</td></tr>
<tr><td>Soy burger</td><td></td><td>12 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>19 g (168 cal)</td><td></td><td>42 g (168 cal)</td><td></td><td>254 gallons</td></tr>
<tr><td>Chickpeas</td><td></td><td>22 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>19 g (168 cal)</td><td></td><td>187 g (747 cal)</td><td></td><td>278 gallons</td></tr>
<tr><td>Goat</td><td></td><td>7 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>19 g (168 cal)</td><td></td><td>0 g (0 cal)</td><td></td><td>282 gallons</td></tr>
<tr><td>Lentils</td><td></td><td>22 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>0 g (0 cal)</td><td></td><td>127 g (509 cal)</td><td></td><td>294 gallons</td></tr>
<tr><td>Milk (1%)</td><td></td><td>60 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>17 g (151 cal)</td><td></td><td>84 g (336 cal)</td><td></td><td>359 gallons</td></tr>
<tr><td>Pork</td><td></td><td>9.5 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>15 g (139 cal)</td><td></td><td>4 g (16 cal)</td><td></td><td>394 gallons</td></tr>
<tr><td>Lamb</td><td></td><td>5.5 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>48 g (432 cal)</td><td></td><td>0 g (0 cal)</td><td></td><td>465 gallons</td></tr>
<tr><td>Beef</td><td></td><td>8 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>33 g (298 cal)</td><td></td><td>0 g (0 cal)</td><td></td><td>850 gallons</td></tr>
<tr><td>Almonds</td><td></td><td>9 ounces</td><td></td><td>56 g (224 cal)</td><td></td><td>126 g (1134 cal)</td><td></td><td>56 g (224 cal)</td><td></td><td>1097 gallons</td></tr>
</tbody></table>
<br />
I've added almonds to the table (using <a href="http://waterfootprint.org/media/downloads/Report47-WaterFootprintCrops-Vol1.pdf">Mr. Hoekstra's data</a> again), as they are rich in protein, use a lot of water, and are getting a bad rap in California for their water use right now. I've also listed fat and carb calories. For those of us trying to get to a low-carb, high-protein diet, soy and maybe milk look okay but these other veggie options are not great.<br />
<br />
Farmers, of course, don't directly care how much protein their products have, but rather how much profit can be made from them. I wasn't able to get profit numbers, but some quick Googling came up with the following prices. If a farmer and his inputs are constrained primarily by water, then poultry farming looks like a good way to go, and once again vegetarian staples appear to be a terrible choice.<br />
<br />
<table>
<tbody>
<tr><th>Food</th><th width="30"></th><th>Water Used</th><th width="30"></th><th>Farm Price</th><th width="30"></th><th>Price per gallon</th></tr>
<tr><td>Eggs</td><td></td><td>1566 m3/tonne</td><td></td><td>$1.90/pound</td><td></td><td>1.013 cents/gallon</td></tr>
<tr><td>Goat</td><td></td><td>5521 m3/tonne</td><td></td><td>$5.25/pound</td><td></td><td>0.794 cents/gallon</td></tr>
<tr><td>Pork</td><td></td><td>5508 m3/tonne</td><td></td><td>$4.06/pound</td><td></td><td>0.615 cents/gallon</td></tr>
<tr><td>Chicken</td><td></td><td>2218 m3/tonne</td><td></td><td>$1.54/pound</td><td></td><td>0.579 cents/gallon</td></tr>
<tr><td>Beef</td><td></td><td>14191 m3/tonne</td><td></td><td>$5.65/pound</td><td></td><td>0.332 cents/gallon</td></tr>
<tr><td>Peas</td><td></td><td>1979 m3/tonne</td><td></td><td>$0.70/pound</td><td></td><td>0.295 cents/gallon</td></tr>
<tr><td>Lamb</td><td></td><td>13007 m3/tonne</td><td></td><td>$4.28/pound</td><td></td><td>0.275 cents/gallon</td></tr>
<tr><td>Milk</td><td></td><td>796 m3/tonne</td><td></td><td>$0.21/pound</td><td></td><td>0.220 cents/gallon</td></tr>
<tr><td>Lentils</td><td></td><td>5874 m3/tonne</td><td></td><td>$0.90/pound</td><td></td><td>0.128 cents/gallon</td></tr>
<tr><td>Almonds</td><td></td><td>16095 m3/tonne</td><td></td><td>$2.00/pound</td><td></td><td>0.104 cents/gallon</td></tr>
<tr><td>Soybeans</td><td></td><td>2145 m3/tonne</td><td></td><td>$0.23/pound</td><td></td><td>0.089 cents/gallon</td></tr>
<tr><td>Chickpeas</td><td></td><td>4177 m3/tonne</td><td></td><td>$0.29/pound</td><td></td><td>0.058 cents/gallon</td></tr>
</tbody></table>
<br />
It's worth mentioning that tap water in California goes for about 0.55 cents/gallon. If farmers paid for water what I pay, most would stop farming. On the other hand, if most residential water users were charged similar rates to farmers, most would stop conserving water. Things are pretty out of whack.<br />
<br />
Prices aren't profit, and California farmers aren't all water constrained. In many places they can pump unlimited (or more precisely, unregulated) amounts of groundwater. In particular, there has been a trend in California of dairies converting to almond orchards. The second table above suggests this is exactly backwards if those products have similar profit margins and are water limited. California farmers are making the move because profit margins on dairy are smaller than almonds and they are not limited by water.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-52329459545235523862014-10-31T00:03:00.003-07:002014-10-31T00:03:33.325-07:00STS-93: Yikes! We don't need any more of these.I just found <a href="http://waynehale.wordpress.com/">Wayne Hale's blog</a>. Be careful reading this thing, I just lost nearly an entire night of sleep. The latest update, which covers <a href="http://waynehale.wordpress.com/2014/10/26/sts-93-we-dont-need-any-more-of-those/">the launch of STS-93</a>, is just breathtaking.<br />
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Here's a video which documents the folks at mission control scrambling to figure out what is going on with their bird during the ascent.</div>
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Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-73550699453084367762014-09-14T15:17:00.001-07:002014-09-14T15:17:18.530-07:00Quick trip to the Sierras<div class="separator" style="clear: both; text-align: left;">
On Friday I took a quick trip to the Sierras to grab some Ponderosa pine forest images with a drone. Initially, the logging road was just gorgeous.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdlKZQ-mfeO3muYeTfkigCBpRPg-OPQYRehv8IZp_PvVg47zxj_ZIIt8HzrK2dS8AoZRFWeNoaZsXBXdMisbG5UwPIw0l4pEHWK7Isg7CsM9mOP1Cmo7hHau98XFgIMxwlrzc/s1600/IMG_3568.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdlKZQ-mfeO3muYeTfkigCBpRPg-OPQYRehv8IZp_PvVg47zxj_ZIIt8HzrK2dS8AoZRFWeNoaZsXBXdMisbG5UwPIw0l4pEHWK7Isg7CsM9mOP1Cmo7hHau98XFgIMxwlrzc/s1600/IMG_3568.JPG" height="426" width="640" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoHTRrxzUlkyZXWdB9Yd9SshMn_XXwQfN-nUGg5vnhjnQn3OWTjFDoSRhsulUd7bSiJ1aDs4BrvZZfCeuKyT_AX9rZXcX3eaal-gC0fqHZsm2XZsCWp1qhbCDn84Di6Q8eJb0/s1600/IMG_3569.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoHTRrxzUlkyZXWdB9Yd9SshMn_XXwQfN-nUGg5vnhjnQn3OWTjFDoSRhsulUd7bSiJ1aDs4BrvZZfCeuKyT_AX9rZXcX3eaal-gC0fqHZsm2XZsCWp1qhbCDn84Di6Q8eJb0/s1600/IMG_3569.JPG" height="426" width="640" /></a></div>
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Then I got to some bits that were less than gorgeous. These roads don't see much use (I saw one other couple in a pickup during several hours on site), and I think these portions are probably just completely ignored until it's time for another logging operation, at which point they probably fill in the worst spots with gravel. There were 18-inch-deep gullies in places, and nasty rocky bits that looked like a dry stream bed. I walked several of these before trying them in the minivan. There were a few uphill sections on which I was glad to have 4 wheel drive.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFwXKGp6V-ttLbxEpGcU5WifCvWVQLyw6z2CXzij5fcl5uiTF3IxKAIFKFPDMO4QAvR8bjZdg53BUZ0HeCFh8RlD6RrjJ7bmz5k-ye-cV5UPbzw4f07SFvKIJM4Y28mxLEPyo/s1600/IMG_3570.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFwXKGp6V-ttLbxEpGcU5WifCvWVQLyw6z2CXzij5fcl5uiTF3IxKAIFKFPDMO4QAvR8bjZdg53BUZ0HeCFh8RlD6RrjJ7bmz5k-ye-cV5UPbzw4f07SFvKIJM4Y28mxLEPyo/s1600/IMG_3570.JPG" height="425" width="640" /></a></div>
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Eventually I got up to my target location. That pile of wood is slash from a logging operation that probably happened in the last few years.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLV5ggzeKSvodgSSWXyP0u6S2ZMQvgDWT0PjMlUydbKOR_dyu7hBvr-G4q9NJifrArmy6YnQkCG9SXbmORnuAY4vyaQMEP0s6s0Wb_cT8JqZ2jD0GTrR7O8IY8pIWdKrvGdp4/s1600/IMG_3571.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLV5ggzeKSvodgSSWXyP0u6S2ZMQvgDWT0PjMlUydbKOR_dyu7hBvr-G4q9NJifrArmy6YnQkCG9SXbmORnuAY4vyaQMEP0s6s0Wb_cT8JqZ2jD0GTrR7O8IY8pIWdKrvGdp4/s1600/IMG_3571.JPG" height="426" width="640" /></a></div>
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Target. Life is good.</div>
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No crashes, nothing broke. However, there are new noises coming from the minivan's power steering system now. So, perhaps I did break something. Overall it was a successful trip.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-45623329848612963022014-06-29T15:59:00.000-07:002014-07-03T10:04:00.928-07:00Early Days on Street ViewDown until I'm done talking to Google about this post.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-55381084750162105882014-05-13T17:40:00.002-07:002014-05-13T17:41:29.637-07:00Happy Birthday to me<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0_eKEDVHJbcZgF0iB43E1mGzt6mhJA3Qbd01HdlCCjoXVF9qETioZ1Tlmx7al4HKmLLJ1mC8y-uD8KExf1sfuMs5euE9M4Svmkl6nZClD45MAfI_uSE3ok31H8eGOKaGvaxw/s1600/IMAG0187.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0_eKEDVHJbcZgF0iB43E1mGzt6mhJA3Qbd01HdlCCjoXVF9qETioZ1Tlmx7al4HKmLLJ1mC8y-uD8KExf1sfuMs5euE9M4Svmkl6nZClD45MAfI_uSE3ok31H8eGOKaGvaxw/s320/IMAG0187.jpg" height="361" width="640" /></a></div>
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It's 5:13pm, and I'm sitting in the shade in my back yard, tweaking some really neat flexure mounts, while keeping an eye on two of my kids and two of their friends frolicking in the pool I built years ago. It's hot out, and there is steady traffic between the two hives near the back of the yard and the fountain to my right. A pair of ducks have been watching the kids too, and though they like the look of all that water they're leaving for someplace less noisy. Lady Jane, our black Labrador, is lying in the grass, which is overdue for mowing, ripping up stems and chewing away. There are stains from fine droplets of sunscreen on the back of my laptop that won't be coming off. Martha will bring my youngest daughter back from gym class in an hour and then we'll head out for my birthday dinner.<br />
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At least once a day, at least one person helps me accomplish something I cannot achieve myself, things I am really happy to be working on. I wonder if I manage to help someone else every day in the same way.<br />
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I have a lot to be thankful for.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-68586276170460030772014-04-23T17:28:00.000-07:002014-04-23T17:28:15.298-07:00Window 8.1 is unusable on a desktopFor the last two years I've been doing a lot of SolidWorks Simulation on my Lenovo W520 laptop. This thing has been great. But I've started doing fluid flow simulations, and it's time for more CPU than a 3.3 GHz (limited by heat load) dual core Sandy Bridge.<br />
<br />
So I built a 6 core Ivy Bridge (i7 4930k) which I overclocked to 4.5 GHz. Very nice. However, I installed Windows 8.1 on it, which turns out to have been wrong. This post is for people who, like me, figure that Windows 8 problems are old news and Microsoft must have fixed it by now.<br />
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Summary: Nope.<br />
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I figured that all those folks bellyaching about the new Windows were just whining about minor UI differences. Windows 8 should benefit from 3 years of code development by thousands of serious engineers at Microsoft. The drivers should be better, and it definitely starts up from sleep faster (and promptly serves me ads). I figured I could deal with different menus or whatever.<br />
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I have learned that Windows 8.1 is unusable for a workstation.<br />
<ul>
<li>Metro apps are full screen. Catastrophe.</li>
<ul>
<li>When I click on a datasheet PDF in Windows 7, it pops up in a window and I stick it next to the Word doc and Excel doc that I'm working on. In Windows 8, the PDF is full screen, with no way to minimize. I can no longer cut and paste numbers into Skype. I can no longer close open documents so that DropBox will avoid cache contention problems.</li>
<li>Full screen is fine for a tablet, but obliterates the entire value of a 39 inch 4K monitor. I spent $500 on that monitor so I could see datasheets, spreadsheet, Word doc, and SolidWorks at the same time.</li>
<li>Basically, this is a step back to the Mac that I had 20 years ago, which ran one application, full screen, at a time.</li>
</ul>
<li>Shortly after the build, I cut power to the computer while it was on. Windows 8 cheerfully told me I had to reinstall the O/S from scratch, and blow away all the data on the machine. I don't keep important data on single machines, but I still lost two hours of setup work. That's not nice. I have not had that problem with Windows 7.</li>
<li>I plugged the 4k monitor into my W520 running Windows 7. It just worked. My Windows 8 box wants to run different font sizes on it, which look terrible.</li>
<li>Windows 8 + Chome + 4k monitor = display problems. It appears Chrome is rendering at half resolution and then upscaling. WTF? This has pushed me to use Internet Explorer, which I dislike. Chrome works fine on the 4k on Windows 7.</li>
<li>Windows 8 + SolidWorks = unreadable fonts in dialog boxes. I mean two-thirds of the character height is overwritten and not visible. So actually unreadable. The SolidWorks folks know they have a problem, and are working on it. And, I found a workaround. But it still looks unnecessarily ugly.</li>
<li>Windows 8 + SolidWorks + 4k monitor = display problems. Not quite the same look as upscaling, but something terrible is clearly happening. Interestingly, if more than half of the SW window is on my 30" monitor, lines drawn on the 39" look okay. But when more than half of the SW window is on my 39" monitor, lines look like crap... even the ones on the smaller half of the window still on the 30".</li>
<li>Windows 7, to find an application: browse through the list on the start button. Window 8: start by knowing the name of the application. Go to the upper right corner of the screen, then search, then type in the name.</li>
<li>Finally, that upper right corner thing. I have two screens. That spot isn't a corner, it's between my two screens. I keep triggering that thing when moving windows, and can't trigger it easily when I want to. Microsoft clearly designed this interface for tablets, and was not concerned with how multi-screen desktop users would use it.</li>
</ul>
And here's the kicker: Microsoft won't swap the Windows 8.1 Pro license I got for a Windows 7 license. I have to buy Windows 7.<br />
<br />
Excel 2013 has one thing I like: multiple spreadsheets open in separate windows, like Word 2010 and like you'd expect.<br />
<br />
Word 2013 has two things I dislike: Saving my notes file takes 20 seconds rather than being nearly instant (bug was reported for a year before Microsoft acknowledged it recently), and entering "µm" now takes two more clicks than it used to -- and nothing else has gotten better in exchange. Lame.<br />
<br />
I suggest not upgrading, folks. No real benefit and significant pain.<br />
<br />
You have (another) angry customer, Microsoft.<br />
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Here's the difference in SolidWorks rendering, on the SAME MONITOR, running in Windows 8, as I shift the window from being 60% on the 30 inch monitor to 40% on the 30 inch monitor (and 60% on the 39 inch):<br />
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30 inch mode: Note that lines are rendered one pixel wide, text is crisp.
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<img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoVPe2j2-JCq0dokT96dpH62qf_yknbMU42UoZXDozjdHrGPCGawj-hz-ZizuFci-3maHvHBmgZ5nG-Ln7KeDVW1OAWEowO4bGCIQhWHifIOHYE8DvBM3xG1W8wxgB7eORAHo/s1600/30+mode.png" />
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39 inch mode: Lines are fatter, antialiasing attempted but wrongly
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<img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8NX4dI7SNmSeV29pSc8CbVrh9F01HiAIFAaS83c4Rb-QLOZRAxTjF8DfVZRSKMKFhF_QgwdJbThWbN6wsQHeS3B02MoYPVg8O30WWTMbFuxuXZxl5NG82hyphenhyphen7w61X-gZeYjAs/s1600/39+mode2.png" />
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<br />Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-50578684343664031092014-01-15T12:31:00.000-08:002014-01-21T00:14:16.454-08:00Sensors, Survey and Surveillance from SpaceThe SkyBox satellites are the first to use area array rather than pushbroom sensors for survey work, but they certainly aren't the first to use area array sensors. I think the first satellites to do that were the KH-11 surveillance satellites, versions of which are still the principle US optical spysats in use today. The first KH-11s sported area array sensors of about the same resolution as a standard definition TV. The most recent KH-11s probably have a focal plane similar to this tiled <a href="http://www.e2v.com/e2v/assets/File/documents/imaging-space-and-scientific-sensors/Papers/Atwood%20SPIE%202012%207021-9%20%20Design%20of%20the%20KMTNet%20large%20format%20CCD%20Camera%20final.pdf">18,000 x 18,000, 10 micron focal plane</a> (shown below, that circle is a foot in diameter).<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiClk2X8YCxdouOO0meUddDKRnhxnuA-TpWKiX30-z8MC8dFaCUuu-MeluwRQsKsqZ7IyCdgFG-SQyeUQJPLCSNfqVkPyaNMK36mDco0b8UK0gyqkTJgFEANiFiIu4NJkFQCLU/s1600/KMTN+detector.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiClk2X8YCxdouOO0meUddDKRnhxnuA-TpWKiX30-z8MC8dFaCUuu-MeluwRQsKsqZ7IyCdgFG-SQyeUQJPLCSNfqVkPyaNMK36mDco0b8UK0gyqkTJgFEANiFiIu4NJkFQCLU/s320/KMTN+detector.jpg" height="320" width="319" /></a></div>
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Optical spysats have two missions; call them surveillance and survey. When you already know where the thing is, that's surveillance. Response time matters, but throughput is usually not a big deal. When you don't know where your thing is, or you don't even know what it is yet, you are doing survey. Throughput is king in survey work, and if response time matters, you have a problem. Coast Guard aerial search and rescue, for example, has this problem. You can read about the difficulties of search at sea in this <a href="http://www.nytimes.com/2014/01/05/magazine/a-speck-in-the-sea.html?_r=1">NY Times article on rescue of a fisherman</a> last July.<br />
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General Schwarzkopf said after the first Gulf War that spysats (he must have been referring to the earlier KH-11s) could not provide useful, timely imagery. He was comparing single pictures of targets after a hit to the target camera footage of his planes, which gave him continuous video snippets of the target before, during, and after a hit. These videos were very popular at press conferences and with his upper management.<br />
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<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/0AjCAuYkrgA?feature=player_embedded' frameborder='0'></iframe></div>
Satellites are excellent for getting access to denied airspace -- there is no other way to take pictures inside China and Russia. But in Iraq, Afghanistan, and Pakistan they are completely outclassed by airplanes and now drones with long-range optics (like the MB-110 reconnaissance pod which I still haven't written up). In a 20 year battle against irrelevancy, I suspect that getting near-real-time imagery, especially video, from orbit has been a major NRO focus. I'm sure the Block IV KH-11 launches in 2005, 2011, and recently in August 2013 can all do real-time downlinks of their imagery through the SDS satellite constellation. However, the second part of real-time is getting a satellite into position to take the picture quickly. The three KH-11s in orbit often cannot get to a surprise target in less than 30 minutes, and cannot provide continuous video coverage. Guaranteeing coverage within 30 minutes would require dozens of satellites. Continuous coverage, if done with satellites 300 km up, would require around 1000. The KH-11 series is expensive (they refer to them as "battleships") and the US will not be launching a big constellation of these.<br />
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The Next Generation Electro-Optical program, which started in 2008 or so, is probably looking at getting the cost of the satellites down into the sub-$500m range, while still using 2+ meter telescopes, so that a dozen or two can be launched over a decade within a budget that NRO can actually sell to Congress. My guess is they won't launch one of these until 2018. In the meantime, <a href="http://skybox.com/">SkyBox Imaging</a> and <a href="http://www.exactearth.com/">ExactEarth</a>, who are both launching constellations of small imaging sats, will be trying to sell much lower-resolution images that can be had more quickly. These civilian operators have 50-60 cm apertures and higher orbits, and so can't deliver the resolution that NRO and NGA customers are used to, and they can't or don't use the SDS or TDRS constellations to relay data in real time. (SkyBox can do video, but then downlinks it 10 to 90 minutes later when they overfly one of their ground stations.) <br />
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The second spysat mission is survey: looking for a needle in a haystack. From 1972 to 1986 we had this in the form of the <a href="http://ambivalentengineer.blogspot.com/2013/04/optical-bar-cameras.html">KH-9 Hexagon</a>, which shot the entire Soviet Union every 2 to 4 months at 1 to 2 foot resolution. The intel community at the time could not search or inspect all that imagery, but the survey imagery was great once they'd found something surprising. Surprise, a new site for making nuclear weapons! Survey answers the question: What did it look like during construction? Or, How many other things like this are there? Nowadays, Big Data and computer vision have got some handle on finding needles in haystacks, but we no longer have the KH-9 or anything like it to supply the survey imagery to search. We still use the U-2 for aerial survey imagery, but we haven't flown that into denied airspace (e.g. Russia and China) for many decades.<br />
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From 1999 to 2005 Boeing ran the <a href="http://en.wikipedia.org/wiki/Future_Imagery_Architecture">Future Imagery Architecture</a> program,which was intended to make a spy satellite that could do radar, survey, and surveillance. The program took too long and ran way over budget, and was eventually salvaged by cancelling the optical portion and having the team design a synthetic aperture radar satellite, which did get launched. (Apparently this was the successor to the <a href="http://en.wikipedia.org/wiki/Lacrosse_(satellite)">Lacrosse</a> radar satellite.)<br />
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As I wrote, SkyBox does survey with a low-resolution area array. They would need about 16,000 orbits to cover the entire surface of the earth, which is 2.7 years with one satellite. I'm sure they can optimize this down a bit by steering left/right when over the ocean. But this is 70 cm GSD imagery.<br />
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Two of the telescopes designed for FIA were <a href="http://en.wikipedia.org/wiki/2012_National_Reconnaissance_Office_space_telescope_donation_to_NASA">donated to NASA in 2012</a>, and the few details that have emerged tell us about late 1990s spy satellites. From 300 km up, they could deliver 7 cm imagery, and had a (circular) field of view of about 50,000 pixels. This could have been used with a 48,000 x 16,000 pixel tiled focal plane array. Using the simple expedient of shooting frames along the line of the ground track, the ground swath would have been 3.2 km wide, and could have surveyed the entire Earth in about 2.7 years (the same number is a coincidence -- spysats fly at half the altitude and this one had twice my presumed field of view for SkyBox).<br />
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However, to keep up with the ground track pixel velocity, the sensors would have to read out at over 6 frames per second. That's almost 5 gigapixels per second. I don't believe area array sensors that big can yet read out that fast with low enough noise. (The recent <a href="http://www.aptina.com/products/image_sensors/ar1411hs/">Aptina AR1411</a> reads out at 1.4 gigapixels per second, but it's much smaller, so the column lines have far less capacitance.)<br />
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The large number is not a result of the specifics of the telescope or sensor design -- it's fundamental to high resolution orbital survey. It's just the rate at which the satellite flies over ground pixels. Getting 5 billion tiny analog charge packets to A/D converters every second is hard. Once there, getting 20 gigabits/second of digital data to the ground is even harder (I don't think it's been done yet either). I'll defer that discussion to a later post.<br />
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Pushbroom sensors are more practical to arrange.<br />
<ul>
<li>The satellite simply stares straight down at the ground. Attitude corrections are very slow.</li>
<li>It's easy to get lots of A/D converters per sensor, you simply add multiple taps to the readout line.</li>
<li>It's easy to tile lots of sensors across the focal plane. You stagger two rows of sensors, so that ground points that fall between the active areas of the first row are imaged by the second row, like this focal plane from ESA Sentinel-2. Once stitched, the resulting imagery has no seams.</li>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgK6xAmUeyjbi8COAO393bVv31OAg4Sc2MDN4mdN5oLVOBRAo_7d5Nc_ruVzz0kuft0Y44Q00EKzdj-EloyeB5LPbW_qBskXykth2ua665hZH45jUxTujvGr4t68VqZOb1D1fo/s1600/Staggered+sensors.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgK6xAmUeyjbi8COAO393bVv31OAg4Sc2MDN4mdN5oLVOBRAo_7d5Nc_ruVzz0kuft0Y44Q00EKzdj-EloyeB5LPbW_qBskXykth2ua665hZH45jUxTujvGr4t68VqZOb1D1fo/s1600/Staggered+sensors.jpg" /></a></div>
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Tiled area array sensors are more difficult, but have the advantage of being able to shoot video, as well as a few long exposures on the night side of the Earth.<br />
<ul>
<li>The image must be held steady while the field of view slides along the ground. Although this can be done by rotating the whole satellite, survey work is going to require rapidly stepping the stabilized field forward along the optical path, several times a second. Fast cycling requires a lightweight optical element, usually the secondary mirror, to have a fast and super precise tip/tilt mechanism to track out the motion. Cycling this element back into position between shots can add vibration to the satellite.</li>
<li>While the secondary mirror is moving the image back into position, the pixel photodiodes must not accumulate charge that affects the values read out. This typically means that either the cycling time can't be used for readout, or (as in the <a href="http://www.visionmap.com/en/products/a3-overview/a3-digital-camera">VisionMap A3</a>) the sensor is an interline CCD with two capacitors per pixel, one of which is shielded. With this choice comes a bunch of minor but annoying problems.</li>
<li>In one line time, charge is transferred from the pixels all the way across the array to the readout. The bit lines can be long and capacitive and add noise.</li>
<li>Take another look at the first pic in this blog post, and note the seams between the active arrays. These are annoying. It's possible to take them out with clever combinations of sparse arrays and stepping patterns.</li>
</ul>
Lenses generally resolve a circular field of view, and pushbroom sensors take a rectangular stripe down the middle. It's possible to put an area array sensor in the leftover upper or lower crescent around a pushbroom sensor. This gives a smaller area sensor, but in the context of a 50,000 pixel diameter focal plane, a "smaller" area sensor might be 10,000 pixels on a side, with 50 times the pixel count of an HD video sensor. This allows for a 10:1 "digital zoom" for context with no loss of display resolution.<br />
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If I were building a government spysat today, I'd want it to do survey work, and I'd make surveillance the secondary mission. Airplanes and drones are better for most surveillance work. I'd want to shoot the whole Earth each year, which can be done with three satellites at 300 km altitude. I'd use a staggered pushbroom array as the primary sensor and a smaller area array for surveillance.<br />
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The step-stare approach that SkyBox is using makes sense when a big, fast area array sensor covering the whole field of view can be had at low risk. Sensors are developing quickly, so this envelope is growing over time, but it's still an order of magnitude away from what large-aperture spysats can do.<br />
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Maybe I'm wrong about that order of magnitude. In 2010 Canon announced a 205 mm square CMOS sensor that supposedly reads out 60 frames per second. Here it is pictured next to a full-frame 35mm DSLR sensor -- it's slightly bigger than the tiled array at the top of this post. Canon did not announce the resolution, but they did say the sensor had 100 times the sensitivity of a DSLR, which suggests a pixel size around 35 microns. That's too big for a spysat focal plane, unless it's specifically for use at night.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2mRYOjaKjD3MSSdyXsRv8syF7GD2j6z-rYbssVs1xn6a-FO87f4kyGkQ8mBsDdI82Wbsf59XFmpTGs9zY24goe3LTjwH_j77IPtLrccFas69tB8a4KFi54ZaEaSogyfPnkf8/s1600/canon_sensor.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2mRYOjaKjD3MSSdyXsRv8syF7GD2j6z-rYbssVs1xn6a-FO87f4kyGkQ8mBsDdI82Wbsf59XFmpTGs9zY24goe3LTjwH_j77IPtLrccFas69tB8a4KFi54ZaEaSogyfPnkf8/s320/canon_sensor.jpg" height="198" width="320" /></a></div>
No subsequent announcement was made suggesting a purpose for this sensor. Canon claims it was a technology demonstration, and I believe that (they would not have been allowed to show a production part for a spysat to the press). Who were they demonstrating that technology to? Is this the focal plane for a Japanese spysat?Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-6461771727217506922013-12-12T01:06:00.001-08:002014-01-15T12:31:51.996-08:00The SkyBox cameraChristmas (and Christmas shopping) is upon us, and I have a big review coming up, but I just can't help myself...<br />
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SkySat-1, from a local startup SkyBox Imaging, was launched on November 21 on a <a href="http://en.wikipedia.org/wiki/Dnepr-1">Russian Dnepr rocket</a>, along with 31 other microsatellites and a package bolted to the 3rd stage. They have a signal, the satellite is alive, and <a href="http://www.skybox.com/news/SkySat1FirstLight">it has seen first light</a>. Yeehah!</div>
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<img src="http://www.skybox.com/uploads/ckfinder/images/Perth2SkyboxBlog(2).png" /></div>
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These folks are using area-array sensors. That's a radical choice, and I'd like to explain why. For context, I'll start with a rough introduction to the usual way of making imaging satellites.</div>
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A traditional visible-band satellite, like the DubaiSat-2 that was launched along with SkySat-1, uses a pushbroom sensor, like this one from <a href="http://www.teledynedalsa.com/imaging/knowledge-center/appnotes/tdi-primer/">DALSA</a>. It has an array of 16,000 (swath) by 500 (track) pixels.</div>
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<img height="227" src="http://www.marketwire.com/library/20100719-Dalsa_Multispectral8.jpg" width="320" /></div>
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The "track" pixel direction is divided into multiple regions, which each handle one color, arranged like this:</div>
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<img src="http://www.teledynedalsa.com/images/imaging/multispectral_400w.jpg" /></div>
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Digital pixels are little photodiodes with an attached capacitor which stores charge accumulated by the exposure. A CCD is a special kind of circuit that can shift a charge from one pixel's capacitor to the next. CCDs are read by shifting the contexts of the entire array along the track direction, which in this second diagram would be to the right. As each line is shifted into the readout line, it is very quickly shifted along the swath direction. At multiple points along the swath there are "taps" where the charge stored is converted into a digital number which represents the brightness of the light on that pixel.</div>
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A pushbroom CCD is special in that it has a readout line for each color region. And, a pushbroom CCD is used in a special way. Rather than expose a steady image on the entire CCD for tens of milliseconds, a moving image is swept across the sensor in the track direction, and in synchrony the pixels are shifted in the same direction.</div>
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A pushbroom CCD can sweep out a much larger image than the size of the CCD. Most photocopiers work this way. The sensor is often the full width of the page, perhaps 9 inches wide, but just a fraction of an inch long. To make an 8.5 x 11 inch image, either the page is scanned across the sensor (page feed), or the sensor is scanned across the page (flatbed).</div>
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In a satellite like DubaiSat-2, a telescope forms an image of some small portion of the earth on the CCD, and the satellite is flown so that the image sweeps across the CCD in the track direction.</div>
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<img height="267" src="http://wtlab.iis.u-tokyo.ac.jp/~wataru/lecture/rsgis/rsnote/cp2/2-11-1.gif" width="400" /></div>
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Let's put some numbers on this thing. If the CCD has 3.5 micron pixels like the DALSA sensor pictured, and the satellite is in an orbit 600 km up, and has a telescope with a focal length of 3 meters, then the pixels, projected back through that telescope to the ground, would be 70 cm on a side. We call 70 cm the ground sample distance (GSD). The telescope might have an aperture of 50cm, which is as big as the U.S. Defense Department will allow (although who knows if they can veto a design from Dubai launched on a Russian rocket). If so, it has a relative aperture of f/6, which will resolve 3.5 micron pixels well with visible light, if diffraction limited.</div>
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The satellite is travelling at 7561 m/s in a north-south direction, but it's ground projection is moving under it at 6911 m/s, because the ground projection is closer to the center of the earth. The Earth is also rotating underneath it at 400 m/s at 30 degrees north of the equator. The combined relative velocity is 6922 m/s. That's 9,900 pixels per second. 9,900 pixels/second x 16,000 pixel swath = 160 megapixels/second. The signal chain from the taps in the CCD probably will not run at this speed well, so the sensor will need at least 4 taps per color region to get the analog to digital converters running at a more reasonable 40 MHz. This is not a big problem.</div>
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A bigger problem is getting enough light. If the CCD has 128 rows of pixels for one color, then the time for the image to slide across the column will be 13 milliseconds, and that's the effective exposure time. If you are taking pictures of your kids outdoors in the sun, with a point&shoot with 3.5 micron pixels, 13 ms with an f/6 aperture is plenty of light. Under a tree that'll still work. From space, the blue sky (it's nearly the same blue looking both up and down) will be superposed on top of whatever picture we take, and images from shaded areas will get washed out. More on this later.</div>
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<div>
Okay, back to SkySat-1. The Skybox Imaging folks would like to shoot video of things, as well as imagery, and don't want to be dependent on a custom sensor. So they are using standard area array sensors rather than pushbroom CCDs.</div>
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In order to shoot video of a spot on the ground, they have to rotate the satellite at almost 1 degree/second so that the telescope stays pointing at that one point on the ground. If it flies directly over that spot, it will take about 90 seconds to go from 30 degrees off nadir in one direction to 30 degrees off in the other direction. In theory, the satellite could shoot imagery this way as well, and that's fine for taking pictures of, ahem, targets.</div>
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A good chunk of the satellite imagery business, however, is about very large things, like crops in California's Central Valley. To shoot something like that, you must cover a lot of area quickly and deal with motion blur, both things that a pushbroom sensor does well.</div>
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<div>
The image sliding across a pushbroom sensor does so continuously, but the pixel charges get shifted in a more discrete manner to avoid smearing them all together. As a result, a pushbroom sensor necessarily sees about 1 pixel of motion blur in the track direction. If SkySat-1 also has 0.7 meter pixels, and just stared straight down at the ground, then to have the same motion blur it would have to have a 93 microsecond exposure. That is not enough time to make out a signal from the readout noise.</div>
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Most satellites use some kind of Cassegrain telescope, which has two mirrors. It's possible to cancel the motion of the ground during the exposure by tilting the secondary mirror, generally with some kind of piezoelectric actuator. This technique is used by the <a href="http://www.visionmap.com/en/products/a3-overview/a3-digital-camera">Visionmap A3 aerial survey camera</a>. It seems to me that it's a good match to SkyBox's light problem. If the sensor is a interline transfer CCD, then it can expose pictures while the secondary mirror stabilizes the image, and cycle the mirror back while the image is read out. Interline transfer CCDs make this possible because they expose the whole image array at the same time and then, before readout, shift the charges into a second set of shielded capacitors that do not accumulate charge from the photodiodes.</div>
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Let's put some numbers on this thing. They'd want an interline transfer CCD that can store a lot of electrons in each pixel, and read them out fast. The best thing I can find right now is the <a href="http://www.truesenseimaging.com/technologies/truesense-7-4-micron-interline-transfer-ccd-platform/43-KAI-16070">KAI-16070</a>, which has 7.4 micron pixels that store up to 44,000 electrons. They could use a 6 meter focal length F/12 Cassegrain, which would give them 74 cm GSD, and a ground velocity of 9,350 pixels/sec.</div>
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The CCD runs at 8 frames per second, so staring straight down the satellite will advance 865 m or 1170 pixels along the ground. This CCD has a 4888 x 3256 pixel format, so we would expect 64% overlap in the forward direction. This is plenty to align the frames to one another, but not enough to substantially improve signal-to-noise ratio (with stacking) or dynamic range (with alternating long and short exposures).<br />
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And this, by the way, is the point of this post. Area array image sensors have seen a huge amount of work in the last 10 years, driven by the competitive and lucrative digital camera market. 16 megapixel interline CCDs with big pixels running at 8 frames per second have only been around for a couple of years at most. If I ran this analysis with the area arrays of five years ago the numbers would come out junk.</div>
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Back to Skybox. When they want video, they can have the CCD read out a 4 megapixel region of interest at 30 fps. This will be easily big enough to fill a HDTV stream.</div>
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They'd want to expose for as long as possible. I figure a 15 millisecond exposure ought to saturate the KAI-16070 pixels looking at a white paper sheet in full sun. During that time the secondary mirror would have to tilt through 95 microradians, or about 20 seconds of arc for those of you who think in base-60. Even this exposure will cause shiny objects like cars to bloom a little, any more and sidewalks and white roofs will saturate.</div>
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To get an idea of how hard it is to shoot things in the shade from orbit, consider that a perfectly white sheet exposed to the whole sky except the sun will be the same brightness as the sky. A light grey object with 20% albedo shaded from half the sky will be just 10% of the brightness of the sky. That means the satellite has to see a grey object through a veil 10 times brighter than the object. If the whole blue sky is 15% as bright as the sun, our light grey object would generate around 660 electrons of signal, swimming in sqrt(7260)=85 electrons of noise. That's a signal to noise ratio of 7.8:1, which actually sounds pretty good. It's a little worse than what SLR makers consider minimum acceptable noise (SNR=10:1), but better than what cellphone camera makers consider minimum acceptable noise (SNR=5:1, I think).</div>
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But SNR values can't be directly compared, because you must correct for sharpness. A camera might have really horrible SNR (like 1:1), but I can make the number better by just blurring out all the high spatial frequency components. The measure of how much scene sharpness is preserved by the camera is MTF (stands for <a href="http://en.wikipedia.org/wiki/Modulation_transfer_function">Modulation Transfer Function</a>). For reference, SLRs mounted on tripods with top-notch lenses generally have MTFs around 40% at their pixel spatial frequency.<br />
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In summary, sharpening can double the high-frequency MTF by reducing SNR by a factor of two. Fancy denoise algorithms change this tradeoff a bit, by making assumptions about what is being looked at. Typical assumptions are that edges are continuous and colors don't have as much contrast as intensity.</div>
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<br /></div>
<div>
The atmosphere blurs things quite a bit on the way up, so visible-band satellites typically have around 7-10% MTF, even with nearly perfect optics. If we do simple sharpening to get an image that looks like 40% MTF (like what we're used to from an SLR), that 20% albedo object in the shade will have SNR of around 2:1. That's not a lot of signal -- you might see something in the noise, but you'll have to try pretty hard.</div>
<div>
<br /></div>
<div>
The bottom line is that recent, fast CCDs have made it possible to use area-array instead of pushbroom sensors for survey satellites. SkyBox Imaging are the first ones to try this idea. Noise and sharpness will be about as good as simple pushbroom sensors, which is to say that dull objects in full-sky shade won't really be visible, and everything brighter than that will.<br />
<br />
[Updated] There are a lot of tricks to make pushbroom sensors work better than what I've presented here.<br />
<br />
<ul>
<li>Most importantly, the sensor can have more rows, maybe 1000 instead of 128 for 8 times the sensitivity. For a simple TDI sensor, that's going to require bigger pixels to store the larger amount of charge that will be accumulated. But...</li>
<li>The sensor can have multiple readouts along each pixel column, e.g. readouts at rows 32, 96, 224, 480, 736, and 992. The initial readouts give short exposures, which can see sunlit objects without accumulating huge numbers of photons. Dedicated short exposure rows mean we can use small pixels, which store less charge. Small pixels enable the use of sensors with more pixels. Multiple long exposure readouts can be added together once digitized. Before adding these long exposures, small amounts of diagonal image drift, which would otherwise cause blur, can be compensated with a single pixel or even half-pixel shift.</li>
</ul>
<br />
[Updated] I've moved the discussion of whether SkyBox was the first to use area arrays to the next post.</div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-75145124834405818082013-10-31T23:00:00.000-07:002014-01-13T14:57:33.773-08:00Hyperloop Traffic<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;">This is a huge post, about a subject that may not be terribly interesting. I suspect most of you will want to skim all but the first section, and come back later when I refer to this post from later posts.</span><br />
<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;"><br /></span>
<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;">Bottom line: If Hyperloop can get daily commuter traffic, at first within the Bay Area and Los Angeles areas, and later between then, then it can gather at least $7b/year of revenue. This is much larger than the $2.2b/year of revenue from the California High Speed Rail projection.</span><br />
<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;"><br /></span>
<span style="font-family: Arial;"><span style="font-size: 15px; line-height: 17px; white-space: pre-wrap;">Daily commute traffic is the most important market. The better Hyperloop addresses this market, the more revenue it will get.</span></span><br />
<span style="font-family: 'Trebuchet MS'; font-size: 17px; font-weight: bold; line-height: 1.15; white-space: pre-wrap;"><br /></span>
<span style="font-family: 'Trebuchet MS'; font-size: 17px; font-weight: bold; line-height: 1.15; white-space: pre-wrap;">The big picture</span><br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I have looked at the California High Speed Rail project’s expected traffic volume (example </span><a href="http://www.hsr.ca.gov/docs/about/ridership/ridership_PR_CSmem2030-2035_0509.pdf" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">here</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">). They are expecting an average of 32,600 people/day to take the train between the LA basin and the Bay Area, and another 8,800 people/day between San Diego and the Bay Area. For comparison, 29,000 people/day currently fly those routes. So they are expecting everyone who currently flies to take the train instead. While this is possible, it’s neither likely (door-to-door times using the train will be slower for most people), nor sufficient (it doesn’t bring in enough money), nor interesting (replacing one service with an equivalent doesn’t grow the economy).</span></div>
<b id="docs-internal-guid-1a946773-12e4-d0fe-1084-f93430a066b1" style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The required investment is $68 billion and they expect $2.2 billion/year in revenue. That’s just not enough revenue. The goal is apparently to break even on operating costs and not need government subsidy, which I find appalling. Of what use is a train if it doesn’t get anyone anywhere faster and it doesn’t make money? About the only other thing it might accomplish is removing traffic from some other system that would otherwise have to be expanded. The trouble is that the overcrowded system most in need of relief is local highways, and the HSR doesn’t do anything about that.</span></div>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I think Hyperloop should have three goals:</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Most Californians should see decreased travel times and improved travel flexibility.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">6% return on capital invested.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Massive new economic activity beyond the billions spent on the transport system directly.</span></div>
</li>
</ul>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To bring in an order of magnitude more revenue, Hyperloop must be used by a lot more people a lot more often. There is only one way to do that: Hyperloop must significantly improve the </span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: italic; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">daily commutes</span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> of </span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: italic; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a million</span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> Californians. Just as the freeway system allows drivers to bypass most surface streets for journeys longer than 20 minutes, Hyperloop must allow drivers to bypass most of the freeway system for journeys longer than 40 minutes.</span></div>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The average California commute is about 30 minutes. 12% of Bay Area and Los Angelino commuters accept commutes at least an hour long. There are two opportunities here. The first and more immediate is to cut 20 or more minutes out of hundreds of thousands of existing commutes within the Bay Area and Los Angeles. The second is to enable daily commuting between Northern and Southern California, and over larger distances in general.</span></div>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Practical commuting over distances like this will cause massive changes, just as the automobile disrupted the previous shapes of cities. Hyperloop can bring together the labor markets in Northern and Southern California, open up gigantic new areas of real estate, save Californians perhaps a hundred million hours a year, and attract a half million passengers a day. (Em, my numbers don't actually support a million per day.)</span></div>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">As detailed below, I project revenue of at least $7b/year.</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$2.8b from existing north/south traffic</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$2.3b from existing commuters</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Eventually, at least $1.9b from new long distance commuters, and perhaps multiple times this much.</span></div>
</li>
</ul>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636"></span><br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636"><span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;">The key to faster commuting is quick transitions between Hyperloop and ordinary car travel, so I have diverged from Elon Musk’s proposal. I will summarize here and leave the details to another post.</span></span></div>
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636">
</span>
<br />
<ul style="margin-bottom: 0pt; margin-top: 0pt;"><span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636">
<li dir="ltr" style="font-family: Arial; font-size: 15px; list-style-type: disc; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="vertical-align: baseline; white-space: pre-wrap;">The capsules I envision have no seats at all -- they are primarily car ferries.</span></div>
</li>
<li dir="ltr" style="font-family: Arial; font-size: 15px; list-style-type: disc; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="vertical-align: baseline; white-space: pre-wrap;">Security would be the same as on our freeway system -- open access and zero delay, along with police surveillance.</span></div>
</li>
<li dir="ltr" style="font-family: Arial; font-size: 15px; list-style-type: disc; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="vertical-align: baseline; white-space: pre-wrap;">The time between capsules while underway would be 1-2 seconds, similar to that of cars on the freeway.</span></div>
</li>
<li dir="ltr" style="font-family: Arial; font-size: 15px; list-style-type: disc; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="vertical-align: baseline; white-space: pre-wrap;">I envision routing the tubes underwater. I just don’t see voters accepting massive overhead tubes in cities.</span></div>
</li>
</span></ul>
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636">
</span>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636"><span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;">My last point of departure is that I propose to carry truck traffic for more diversified revenue.</span></span></div>
<span id="docs-internal-guid-1ca5c197-12f9-b9bc-80c1-fee1a1645636">
</span><span style="font-family: 'Trebuchet MS'; font-size: 17px; font-weight: bold; line-height: 1.15; white-space: pre-wrap;"><br /></span>
<span style="font-family: 'Trebuchet MS'; font-size: 17px; font-weight: bold; line-height: 1.15; white-space: pre-wrap;">Northern California to/from Southern California non-commute traffic</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The following analysis leads me to expect that, perhaps five years after initial operation, the north-south link would carry 26 thousand one-way revenue-generating capsule trips per day, from the replacement of trips that people take today.</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">10k/day replace I-5 truck traffic</span></div>
</li>
</ul>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">8k/day replace I-5 car traffic</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">7k/day replace flights and subsequent car rentals</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">350/day replaces flights which are segments of longer flights</span></div>
</li>
</ul>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To be attractive to truck traffic, a north/south capsule ride must be priced around $300, which makes a car ride $75 and a bus ride under $20. North/south revenue will be around $2.8b/year.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Why Trucks?</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Carrying 18-wheeler trailers will require a substantially bigger capsule and tube than carrying sedans, and so substantially more capital investment. I don’t have an estimate of how much more capital investment, but I do have an estimate for the expected revenue from truck replacement traffic: about $1b/year from 10k capsules/day on the north-south link. This is perhaps 15% of the total revenue stream.</span></div>
<b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Nationally, people spend one-third as much on truck freight as on car travel, but they spend twice as much on truck freight as air travel. This leads me to believe that truck replacement revenue for Hyperloop will eventually be more like 20% of the total revenue stream.</span></div>
<div dir="ltr">
<table style="border-collapse: collapse; border: none; width: 624px;"><colgroup><col width="*"></col><col width="*"></col><col width="*"></col><col width="*"></col><col width="*"></col><col width="*"></col></colgroup><tbody>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">ca. 2009</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">tonne-km freight</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(million)</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">revenue</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">($/tonne-km)</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">passenger-km</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(million)</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">revenue</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">($/pass-km)</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">2010 user costs</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(billion $)</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Car</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">4,507,134</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.168*</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$757*</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Truck</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">1,929,201</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.113</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$250</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Air</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">17,559</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.671</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">887,941</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.075</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$110</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Intercity Rail</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">2,309,811</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.021</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">9,518</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.191</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">$ 50</span></div>
</td></tr>
</tbody></table>
</div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(Data from the </span><a href="http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/index.html" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">Research and Innovative Technology Administratio’s Transportation Statistics</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">.)</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(*Car operating costs are </span><a href="http://newsroom.aaa.com/wp-content/uploads/2013/04/YourDrivingCosts2013.pdf" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">incremental operating costs for medium sedan in 2013 from AAA</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">)</span></div>
<br />
<span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;"></span>
<br />
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The decision to carry trucks will hinge on the return off an incremental billion dollars of revenue versus the incremental investment for bigger tubes.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I-5 Truck bridge case: 10k capsules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">A fleet operator with tractors in both LA and SF can move freight between the two more cheaply over Hyperloop than over I-5.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b id="docs-internal-guid-1a946773-12e8-2f57-39bc-27799bcfa937" style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Over-the-road truck drivers (the ones on the road for two weeks at a time) are paid </span><a href="http://voices.yahoo.com/over-road-truck-drivers-salary-worth-it-3739138.html" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">$0.19 to $0.25/km</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">. The vehicle depreciates $.06 to $.07/km. They burn $0.27/km of diesel. This adds to around $0.55/km in 2013. Trucks averaged 11.3 cents per km-ton in 2009, which suggests the average load was around 5 tons, which seems reasonable.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So, the 600 km from SF to LA costs a truck operator around $330. It’s possible for Hyperloop to charge a premium, because the capsule trip gets the load to the destination 5 hours sooner. But the premium will only be paid for a small number of loads. In order to get most of this business, a capsule trip will cost around $300.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The current truck traffic on I-5 is 10k trucks/day (one-way). 10k capsules/day is more traffic than I expect from air traffic replacement. Because the truck bridge case will also be more price sensitive, it will probably set the capsule trip price for long-distance routes..</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Payloads</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The initial payloads with the greatest revenue potential are cars and 18-wheeler trailers, and eventually busses and container freight.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr">
<table style="border-collapse: collapse; border: none;"><colgroup><col width="287"></col><col width="108"></col><col width="131"></col><col width="98"></col></colgroup><tbody>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Max weight</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Frontal area</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Length</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><img height="29px;" src="https://lh4.googleusercontent.com/7Dyqcxrg3yy9HcCc5MKtZEZpju2gxC2xgRWJZ5Tnslh_qbsqPoTA1v_z9KbjZawibAPocnO94SaGghXduOvkincy4YRO7VcOaDfvkjL8u5WGwZQSvy-3lwr9" width="272px;" />*<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">10.5 tonnes</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">1.7 m x 2.0 m</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">21.0 m</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><img height="103px;" src="https://lh3.googleusercontent.com/w6M-xh5BdPL6PQc0CJbeBsybeN_wqC6Gih_155-rwuKOrwv395ZTmIsGHfrmI2rsaIg2dLc8p8HH3T4IbFqVkmvLKtujkjuxuUBGCNC3LJZl7sMrKQGrxccB" width="272px;" />*<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">30.8 tonnes</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">4.12 m x 2.43 m</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">16.15 m</span></div>
<div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(just the trailer)</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><img height="127px;" src="https://lh6.googleusercontent.com/1vuWaOEOqLB81hP4COn36_dQN2lfaZhgGsCcmmEExFHac2EQIBAP3FdKwPgIVo-VbuFPTHAOITlamnhc57WkkaFPZCCvgmRx1ToSJLKUbqt5fJJxCcgaBfok" width="272px;" />*<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">23 tonnes</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">3.5 m x 2.6 m</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">13.7 m</span></div>
</td></tr>
<tr style="height: 0px;"><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><img height="135px;" src="https://lh5.googleusercontent.com/rMb-kOuf1n4Y8VvPegV4ae__vl3VDntXqGL5shYAqH5cXRzkYofNJ0QQT7I8jTi1mRIcIsk5w5BqGnjZxT1yEG2-wDMP2RTIIBudSgWKBYzwMmc-FbwOVXEI" width="272px;" />*<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">32.5 tonnes</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">2.9 m x 2.5 m</span></div>
</td><td style="border: 1px solid #000000; padding: 7px 7px 7px 7px; vertical-align: top;"><div dir="ltr" style="line-height: 1; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">13.7 m</span></div>
</td></tr>
</tbody></table>
</div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The containing capsule will have a payload diameter of 4 to 5 meters. The larger number is if we wish to back standard 18-wheelers directly into the capsule. The smaller number is if we are willing to take the wheels off the trailer first.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Tube diameter will be 6 to 7 meters, about 2x that of the Hyperloop-alpha proposal.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I-5 Car bridge case: 8k capsules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Here’s an interesting statistic: more people drive from northern to southern California than fly: Caltrans: </span><a href="http://www.dot.ca.gov/hq/traffops/saferesr/trafdata/2011TrafficVolumesAug2012.pdf" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">2011 California Traffic Volumes</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">There are currently 30k cars/day travelling between LA and SF, each burning $60 of fuel and 6 hours of driver time. As above, four cars can share a Hyperloop capsule, with an amortized ticket cost of $75/car. The driver can save nearly a day for $15.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I’ll assume nearly all drivers will take the Hyperloop, and traffic may increase due to greater convenience. This would be 8000 capsules/day.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Flight+rental case: 7k capsules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Consider someone taking a flight down to LA, then renting a car for 5 days.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Shuttle<span class="Apple-tab-span" style="white-space: pre;"> </span>$70<span class="Apple-tab-span" style="white-space: pre;"> </span>1 hour<span class="Apple-tab-span" style="white-space: pre;"> </span>(at one-way, might have to pay 2-ways, or pay parking)</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Security<span class="Apple-tab-span" style="white-space: pre;"> </span>1 hour</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Flight<span class="Apple-tab-span" style="white-space: pre;"> </span>$138<span class="Apple-tab-span" style="white-space: pre;"> </span>1 hour<span class="Apple-tab-span" style="white-space: pre;"> </span>(one way)</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Car<span class="Apple-tab-span" style="white-space: pre;"> </span>$188<span class="Apple-tab-span" style="white-space: pre;"> </span>30 min<span class="Apple-tab-span" style="white-space: pre;"> </span>(5 days, compact)</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Total<span class="Apple-tab-span" style="white-space: pre;"> </span>$396<span class="Apple-tab-span" style="white-space: pre;"> </span>3:30</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">8 million people do this every year between the Bay Area and Los Angeles or San Diego.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The Hyperloop is a total win, even if only a single car takes a capsule.</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">4 cars share a $300 ticket, $75 each, about 5 times cheaper, and you get your own car. And, you don’t have to pay to park your own car at the airport.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Assuming it takes 30 minutes to drive to the Hyperloop station, and an hour to get to LA, you’ve saved two hours in each direction. </span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">If there are more people in the car (say, a family of 4), you must buy extra plane tickets and shuttle fares. The Hyperloop option costs nothing more.</span></div>
</li>
</ul>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Assume Hyperloop gets </span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: italic; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">all </span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">of this traffic. Assume average vehicle loading is 1.5 people/car, this is 22,000 people/day and 14,800 cars/day. Assuming an average of 2 cars/capsule (many people will want their own capsule), that’s 7380 capsules/day or $800m/year in revenue to Hyperloop.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">At 20% to 75% of the price, and less than half the time, we should expect an increase in this traffic volume, and Hyperloop will see all that additional traffic.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Airport Shuttle flight case: 350 capules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Not all the people flying between the Bay Area and Southern California are renting a car. For 2.5m people per year, this hop is one of at least two. For instance, when flying from San Francisco to Phoenix one generally stops in LAX along the way.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Airports could run a bus-over-Hyperloop service between airport pairs to move all this traffic off airplanes. They win in two ways: first, they open up runway slots to more profitable longer-distance routes. Second, the airports essentially get into a high-margin local airline business. Finally, the airlines win because they can pack their airplanes better, since passengers may be more willing to accept a one-Hyperloop, one-plane trip instead of a nonstop, if the Hyperloop-using hop gets them to the destination sooner.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">It’s about 7000 people/day. Assuming busses with 20 people (⅓ full), that’s about 350 capsules per day. This would be incredibly convenient for passengers, as there would be a bus leaving from each of the three major airports in each area about every 20 minutes.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Commute traffic</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Just the traffic from replacing portions of existing long commutes is huge:</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">105k/day Bay Area commute capsules (half of all existing >50 minute commutes)</span></div>
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<li dir="ltr" style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">125k/day Los Angeles commute capsules (¼ of existing >50 minute commutes)</span></div>
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</ul>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Capsule rides would average about $60 and carry four cars. Yearly revenue would be $2.3b/year. However, this estimate is sensitive to the distribution of Hyperloop terminal, and the time it takes to get through these terminals.</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span>
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Quick trips really matter. For every minute saved, per trip, I expect an additional 9k/day commute capsules and $135m/year in revenue. This traffic increase is strongly nonlinear, however. If we could get the trip times down to around 35 minutes per trip, we'd expect to see 40k/day extra commute capsules per minute saved (and $600m/year in additional revenue).</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span>
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Extra terminals (in the right places) would really matter, especially in inland Los Angeles, Orange, San Diego, and Contra Costa counties, where I expect each terminal to support 16k/day commute capsules and $235m/year in revenue.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Because the north/south door-to-door time will be about an hour, it will be possible to have a daily commute between northern and southern California. Even if just 1% of commuters use Hyperloop over long distance runs, this is a colossal amount of traffic: 25k capsules/day, bringing in $1.9b/year.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Existing Bay Area commuter case: 105k capsules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The Bay Area has the largest fraction of long distance commutes in the nation. </span><a href="http://blogs.kqed.org/newsfix/2013/03/05/san-francisco-bay-area-nations-capital-for-megacommuting/" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">2% of commuters</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> travel at least 50 miles and 90 minutes, each way. About 12% of commuters travel 60 minutes each way, and the average commute is 30 minutes.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Using the 2011 U.S. Census ACS data, I predict there are 420,000 commuters in the Bay Area with at least a 50 minute commute. As shown in the map below (created with </span><a href="http://www.trulia.com/local#commute/san-francisco-ca" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">Trulia’s excellent tool</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">), at least half of these commuters could be within 15 minutes of a Hyperloop terminal, and so could reduce their commute by 20 minutes and 15 miles with a Hyperloop jump. So a local Hyperloop (with 21 terminals as shown) would have a market of around 420k car trips per day. At four cars per capsule, that’s 105k capsule trips per day.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">20 miles of commuting costs around $4.05 each way (using AAA’s </span><a href="http://newsroom.aaa.com/wp-content/uploads/2013/04/YourDrivingCosts2013.pdf" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">$0.27/mile incremental cost for medium sedan in 2013</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">). 20 minutes of the person’s time is worth something as well, at least $6. Each local car trip could be sold for $10, so yearly revenue for trips within the Bay Area would be $1.05b.</span><img height="847px;" src="https://lh6.googleusercontent.com/XQII93bUuNJNJc-AhqGVrBRHCuvxZS2cTUTPb_fJc92iWpcjuk9gipyHIfhXm3v_m2yAVeP2a6ZfgQrwa7uIgKApEXplxGik4E41V-tVhXpJ1RA2U-FQLMGO" width="624px;" /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Existing Los Angeles commuter case: 125k capsules/day</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The Los Angeles commute market is both more lucrative than the Bay Area’s (</span><a href="http://www.dailynews.com/general-news/20130305/average-commute-for-la-county-residents-294-minutes-in-2011" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">620,000 commutes are at least 60 minutes</span></a><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, 1,100,000 are at least 50 minutes) and more problematic, as more of the population is farther from the water. Nonetheless, a Hyperloop can be run down the coast and reach perhaps ¼ of the population in 15 minutes or less.</span><img height="495px;" src="https://lh5.googleusercontent.com/22orPHVbh5oTxleX7wkQ32jKy5zq2rAuahqtlztZVcUZsbXRehNTs-2oHAGGwgiwuslaOn3HOoWzBCHFAhuUCUFgntU2ZADi152VuEv2vfjrlZU0uf025DiK" width="624px;" /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Again using ACS data, I predict there are 1 million commuters in Los Angeles with at least a 50 minute commute. The core 8 Hyperloop transfer stations shown would service 250,000 of these commuters and bring in $1.25b/year.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><b style="font-weight: normal;"><br /><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The map above shows a terminal in the southern San Fernando Valley, which would require a 10 mile tunnel bore through the Santa Monica mountains. There are several other places where tunnel bores or perhaps cut-and-cover through lower-cost real estate could get to lucrative markets. The map above also shows 5 terminals in Santa Barbara, Ventura, and San Diego, which are not currently suburbs of Los Angeles for many commuters.</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span>
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Tunneling cost is not necessarily prohibitive: A 5 mile x 15-foot diameter tunnel was recently completed under San Francisco Bay for $286 million. The tunnel imagined above would be three times the diameter and twice and long, so perhaps four times the cost. A $1b capital outlay to bring in $150m/year seems quite reasonable.</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /><span style="vertical-align: baseline;"></span><span style="vertical-align: baseline;">There is a significant externalized benefit: these 250,000 commuters would no longer be on the 405 freeway for most of their trip. The Hyperloop would unload a huge amount of traffic from the freeway system, which should speed up even those commutes that can’t be serviced by Hyperloop.</span></span></div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-77270408835687391532013-09-18T17:43:00.000-07:002013-10-05T21:29:52.309-07:00Hyperloop heat balance, fixed<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Last month I complained that the Hyperloop-alpha proposal has a heat balance problem. Here is the fix for that problem, as promised. I’ve broken up my changes to the design in a series of steps, to make it easier to see that each step is individually beneficial.</span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Step 1: Hyperloop + 3 MPa steam heat dump</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">My numbers don’t exactly match Mr. Musk’s. It seems we have slightly different specific heats for low pressure air, among other things. This diagram should serve as a base case which can be compared directly to the diagram from the Hyperloop-alpha proposal (check the last blog post).</span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I’ve detailed the steam heat dump system to run up to 3 MPa. Water is sourced from a small tank and steam is dumped into a much larger tank. The tanks are connected, so that as the steam pressure rises so too does the water pressure, which should reduce pumping losses. Eventually even the small tank is completely filled with steam. I've accounted for the two tanks as a single tank here, as the wall-in-the-middle detail should not affect the mass budget at all.</span></div>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">As I predicted in my last post, the heat dump tank is far too big... at least 12 meters long. The tube taking bypass air to the rear nozzle is also far too big, and will interfere with the passenger compartment. Finally, the battery to run the turbines is gigantic.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8WGscF-Kw00HdsJFfLipKv-tWpH4oYLoh2buH-00uakEW_o6nmxX7DYOefg0_Ncq1dKw6e_9ztuu_dcxx8J6brcXypGCNN0LU4mHnGiYewHxPJSgGiNZtzLHrwtOOByAwbr4/s1600/img1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8WGscF-Kw00HdsJFfLipKv-tWpH4oYLoh2buH-00uakEW_o6nmxX7DYOefg0_Ncq1dKw6e_9ztuu_dcxx8J6brcXypGCNN0LU4mHnGiYewHxPJSgGiNZtzLHrwtOOByAwbr4/s1600/img1.png" /></a></div>
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></div>
<h2 dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Step 2: ... + bypass intercooler</span></h2>
<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">By picking off the air output from before rather than after the first intercooler, the heat load is radically reduced to practical dimensions. The heat going through the first intercooler is not a typo... it's really been reduced to 10% of the prior value. Part of this reduction comes from balancing the pressure ratios across the two compressors. Unfortunately, the bypass tube is now even larger and less practical.</span></div>
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<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Step 3: ... + Reduced Tube Pressure</span></h2>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Reducing the pressure in the transport tube to 25 Pascals decreases the compressor power, but oddly increases the amount of cooling required. That's because we're still cooling the same mass flow of air, but compressing that air more.</span></div>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The cooling tank gets larger, but note that the battery gets cut in half, for significant savings in mass and cost. The bypass tube is smaller but still too large.</span></div>
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<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;">Reducing tube pressure should not cause problems with the vacuum pumps. 25 Pa is considered a "rough" vacuum, and corresponds to an altitude of 59 km, where helium balloons operate. The mean free path in this gas is around 0.3 mm, which is small enough relative to vacuum pump turbine blades that the gas still acts like a gas. Ordinary vacuum pumps will work fine.</span></div>
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<span style="font-family: Arial; font-size: 15px; line-height: 17px; white-space: pre-wrap;">Turbomolecular pumps, which use different aerodynamics than regular vacuum pumps, generally start operating at 10 Pa or less. I am not suggesting we drop into that range.</span></div>
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<span style="background-color: transparent; color: black; font-family: 'Trebuchet MS'; font-size: 17px; font-style: normal; font-variant: normal; font-weight: bold; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Step 4: ... + Cryogenic Heat Dump + Intake Intercooler</span></h2>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The intercoolers above are removing nearly all the energy added by the turbines. We can avoid adding so much energy in the first place if the turbines operate on cryogenically cold air. This is a big step, but it's necessary because the capsule design in Step 3 is too bulky.</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
<b id="docs-internal-guid-7f37f7ac-3303-42d6-f4c6-78013d46b9ac" style="font-weight: normal;"><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
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<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To do it, we swap the water/steam heat dump for a more compact but substantially heavier liquid air heat dump. Boiling liquid air does not absorb as much heat as boiling water, but it also does not expand as much. For the same heat absorbed, the tank weighs less but the fluid weighs far more.</span></div>
<b style="font-weight: normal;"><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
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<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The real magic, however, is that the heat is absorbed at a much lower temperature. The intercooler output will now approach the cold sink temperature of 75 Kelvin. Once again, the battery loses more weight than we add to the heat dump, for a net savings of cost and mass.</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
<b style="font-weight: normal;"><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
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<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The high speed, low density intake intercooler here is similar to but much less extreme than the one proposed for the Skylon spaceplane. It is not completely settled technology but much of the R&D has already been done. In particular, one of the issues would be clogging from frozen water and CO</span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 9px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: sub; white-space: pre-wrap;">2</span><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> ice. In an operating system, the tube air would be dried by prior passages of capsules. So clogging would mainly be an issue when restarting.</span><br />
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div>
<b style="font-weight: normal;"><span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"></span></b>
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<div dir="ltr" style="line-height: 1.15; margin-bottom: 0pt; margin-top: 0pt;">
<span style="background-color: transparent; color: black; font-family: Arial; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The heat dump can also be used as a source of air. For instance, at low speeds the bow intake compressor may not supply enough air for the air bearings. Make-up air can be taken from the heat dump. In an emergency, while waiting for the tube to repressurize, air from the heat dump tank could be used to supply 20 occupants with breathing air for 20 hours.</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgksTQeJjxJEbqz4xZHY-SwHLiAQ1gHrpnMq37p8kMNOSlwl1GGKZ13T4DzQ_R_FdpuLt2js6j-rR68Sn6IfGL7ts2ZlNfkTLoeu-pq0kwmtx7Xy7eheWthSuiaHsvI9mUa6QU/s1600/img4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgksTQeJjxJEbqz4xZHY-SwHLiAQ1gHrpnMq37p8kMNOSlwl1GGKZ13T4DzQ_R_FdpuLt2js6j-rR68Sn6IfGL7ts2ZlNfkTLoeu-pq0kwmtx7Xy7eheWthSuiaHsvI9mUa6QU/s1600/img4.png" /></a></div>
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<span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;"></span>
<span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;"></span><span style="font-family: Arial; font-size: 15px; vertical-align: baseline; white-space: pre-wrap;">I think this design largely achieves what Mr. Musk was attempting to accomplish.</span>Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-22788281384382019202013-08-14T19:38:00.001-07:002013-10-05T21:28:40.466-07:00Hyperloop heat balance<div>
Key points:<br />
<ul>
<li>The Hyperloop proposal implies a steam tank almost as large as the entire vehicle, and at least 3200 kg, which is not accounted for in the Hyperloop mass budget. This is a design breaker.</li>
<li>The capsule as configured is using most of it's power to drive a refrigerator which cools the air in the tube. This refrigerator is not mentioned as such.</li>
<li>The refrigerator, as configured, will not cool the tube air back to it's ambient temperature. But refrigeration is unnecessary.</li>
</ul>
I understand that Elon commutes from Los Angeles to San Francisco every week, and that the high speed rail project will not help him. I imagine that his frustration with this commute is exactly what has kept bringing his attention back to this Hyperloop thing for so long. I'm sure the boards at both SpaceX and Tesla have threatened to fire him if he starts another high-risk startup. The guy has a tough life. :)</div>
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<br />
The Hyperloop proposal has one big idea that I like: the air bearings, rather than the usual magnetic levitation. Air bearings are a well developed technology, and require much less capital in the track. I had not realized that air bearings were a feasible idea for high speed transport, as this is the first I've read about their air requirements at high speed. (I called three air bearing companies to verify Elon's numbers, and none of them could offer any guidance on air consumption or even stable operation at near-sonic velocity.) Elon is implying a 2000:1 lift/drag ratio for the passenger version, and a 2500:1 lift/drag ratio for the vehicle version. That's incredibly good. Maglev lift/drag ratios are generally rise to 200:1, which is considered really good. The Livermore maglev requires substantial forward speed before it gets that efficient. If Elon's numbers are real then air bearings are awesome... but I'd like to see some evidence.<br />
<br />
I don't quite understand Elon's bearing drag power numbers. Drag power is usually just vehicle speed times the drag force. He's got an extra factor in there which adds about 10%, and I'm not sure where that comes from. It's not compressor power, because that is much greater. If we add the compressor power to the drag power, we get L/D ratios of 426:1 and 634:1 for the two configurations. Those are still game changing numbers. These numbers matter because if the air demand of the bearings is higher, the compressor power will increase. If the compressor power increases too much, the battery will get too big and the Hyperloop idea will not work.<br />
<br />
The Hyperloop proposal has another big idea that I don't understand: the Kantrowitz limit. It's clearly a big problem, because the drag coefficient implied by Elon's numbers here is 3.95. (That number is suspiciously close to an integer, and suggests that the drag numbers are back-of-envelope and not the result of simulation.) Compare that to a Tesla S (0.24), or a bullet (0.29). The only saving grace is that his predicted aerodynamic drag (910 N for the vehicle-carrying capsule) isn't too much more than the bearing drag (187 N), even if you include the prorated compressor power in the latter number (740 N).<br />
<br />
At one point, Elon insists that propulsive power should be delivered through the track, rather than from the vehicle. But his propulsive power (628 kW) is less than the compressor power (868 kW) that the vehicle is already signed up to provide. It might be simpler to just let the vehicle do the whole job and let the track be passive. He's already suggested using huge battery packs to deliver the propulsion power, so the only change is to put those packs on the vehicle. This is a nit, let me get on to my main point.<br />
<br />
The proposed bypass refrigerator scheme is fascinating but flawed. Here's the flow diagram for the vehicle-carrying Hyperloop. There is a typo: the air coming out of the second compressor should be at 594 K, not 59 K, assuming that second compressor is 72.4% efficient like the first one is.<br />
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There are much bigger problems than typos here.<br />
<ul>
<li>The air in the tube is not going to be 19 C. Those Hyperloop capsules dissipate 868 kW of compressor power and 285 kW of propulsive power. As drawn above, that propulsive power is going to be primarily dissipated into the air in the tube, heating it tremendously. There is also 59 kW of bearing drag that will be dissipated into the tube wall and somewhat into the air.</li>
<li>As drawn above, the intercooler is actually acting as a refrigerator. The air expanded out the back would leave at around 126 Kelvin... 147 degrees C below freezing! This will suck 209 kW of heat out of the tube air (49 kW for the passenger-only version).</li>
<li>The intercooler refrigerator does not balance the propulsive drag heating. Combining the two, I find that the vehicle will still dump 76 kW into the air, heating the air in the tube by 24 C (35 C for the passenger-only version). By increasing the intermediate pressure and intercooler heat load a bit, this problem can be fixed.</li>
<li>There is no way the output temp of a lightweight intercooler will be within 7 C of the incoming water temperature.</li>
<li>The water is absorbing 852 kW, or 2185 J/g. The water flow rate should be 327 g/sec, not 390 g/sec, to fully boil the water at normal atmospheric pressure. But that's wrong too...</li>
<li>To make the steam tank reasonably small, the steam will have to be held at high pressure. Boiling 20 C input water at 450 psi would absorb 2800 J/g and produce steam at 507 K. The water rate would then be 304 g/s, the tank would be 638 kg and <b>42.5 m<sup>3</sup>.</b> That's clearly far too large (it's as big as the whole vehicle), but that's the largest pressure <a href="http://www.engineeringtoolbox.com/saturated-steam-properties-d_457.html">my steam table</a> goes to. Even if the steam is heated to 857 K (supercritical), I don't think the steam tank will be small enough to work.</li>
<li>The steam tank will be heavy. Assuming carbon composite overwrap construction and 100 MPa working strain, the steam tank will weigh 3200 kg. Changing the steam temperature and pressure conditions will vary this a little, but not much.</li>
</ul>
As a first step, I would take the bypass air directly from the axial compressor, which will remove about 80% of the heat load on the intercooler. A 5x reduction in the size of the steam tank will get the mass budget back under control, but the steam tank will still be awkwardly large. As a bonus this should deliver 70% more thrust, but that's still too small to matter much.<br />
<br />
It should be possible to dump a fair bit of compressor heat from a radiator on the surface of the capsule. I think this can reduce the heat load on the intercooler and steam tank by another factor of two, which should bring the steam tank volume into a more reasonable range. It will still be a major component in the vehicle design.<br />
<br />
As a next step, the vehicle can be slowed, perhaps by 10%, which allows some of the air in front of the vehicle to actually accelerate up to the alpha proposal mach .91 number as it goes around. The compressor inlet and mass flow can then be downsized since it need only handle a portion of the airflow. I think it should be possible to cut the compressor power numbers in half this way.<br />
<br />
In my next post I'll work the numbers on these suggestions.</div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-43859650070624411112013-07-16T13:06:00.000-07:002013-12-12T14:48:14.470-08:00Pacific Rim<span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 13px; line-height: 15.359375px;">This isn't a movie review. There are already</span><span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 13px; line-height: 15.359375px;"> lots of movie reviews for Pacific Rim.</span><br />
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Rather, I want to ask the question, why was this movie weak in the ways that it was?</div>
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First: suspension of disbelief. If faced with 200 foot tall monsters that kill tens of thousands and wreck billions of dollars of equipment and property, we all know the US military will respond. First with battleships</div>
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<img class="qtext_image" detected="http://upload.wikimedia.org/wikipedia/commons/e/ea/BB61_USS_Iowa_BB61_broadside_USN.jpg" npdkey="hj7hf1c20.4v6h8xd3na7wg66r" src="http://qph.is.quoracdn.net/main-qimg-21599812ab76cc914f9201b80d2b2992" style="border: 0px; display: inline; margin: 3px 0px 2px; max-width: 100%; padding: 0px;" /></div>
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and torpedoes.</div>
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<img detected="http://img.youtube.com/vi/jlpx4DMGzYI/hqdefault.jpg" display_type="3" npdkey="hj7hhhdb0.obi28vhv7t0ara4i" snippet="A submarine torpedo tears a destroyer battleship in two." src="http://img.youtube.com/vi/jlpx4DMGzYI/hqdefault.jpg" start_time="" style="border: 0px; display: inline; margin: 3px 0px 2px; max-width: 100%; padding: 0px;" title="Australian Submarine Torpedo Test "Hits a Destroyer"" type="youtube" url="http://www.youtube.com/watch?v=jlpx4DMGzYI" video_id="jlpx4DMGzYI" /></div>
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If that doesn't work, we'll try this, especially since the target is in a known spot well away from large population concentrations.</div>
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Those are the hammers we have. The film did not suggest any reasons why these things were tried and failed. Since the target audience is quite familiar with these things, that's a problem.</div>
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I personally needed to see something about no explosions or shock waves near a Kaiju. Something that knocks out all the standard responses. This would get rid of range weapons, and turn the Kaiju/Jaeger fight into a brawl with knives, teeth, and claws, which is what we want.</div>
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<span npdkey="hj7hy6sw0.8kdtfhtjkyo2bj4i" style="margin: 0px; padding: 0px;">The movie has a germ of a good idea: no electronics near Kaijus. This could have been seriously cool, because it means you must use a person as the control system. I think the idea of multiple people would have been even better with NO electronics and NO drift. Advanced puppets are driven by multiple people. It takes teamwork, practice, and real, visible communication, which would have worked better for communicating a storyline.</span></div>
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The film has another good idea: the Kaiju keep getting bigger over many years. This is fabulous, because it gives us time to develop Jaegers.</div>
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For me, the point of the film was to develop a visual language for BIG. It worked where the film used familiar references. Cars, streetlights, trucks. Water coming off the monsters worked well because water has a characteristic scale.</div>
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Once the scene moved underwater, we lost all of these familiar references. The Jaegers and Kaiju looked small underwater.</div>
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Lifting the Jaegers with helicopters, and having them inside large strong enclosures, violated the language. To be lifted by helicopters, they would have had to be fluffy. I don't want fluffy Jaegers. I want Jaegers that sink in water: denser and more heavily armored than a battleship.</div>
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And the enclosures for the Jaegers were wrong. The point of building something really big is that there isn't something bigger. Really big stuff, like a battleship, is built outside. Things like battleships don't need to be protected from the weather, and the folks that work on them don't either. Perhaps they use portable shelters. You have gantry cranes for lifting pieces into position, like this:</div>
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Finally, go take a look at that battleship pic at the top of the post again. Do you see any big air intakes? No. That's because air intakes and turbines are flimsy things that have to be carefully engineered against bird strikes. The big turbine intake on Gypsy Danger looked flimsy too. That's a problem.</div>
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I think the Jaegers should have been actuated by steam cylinders, so that as they moved great billowing clouds of steam shot out of the joints. That steam would be heated by a nuclear reactor. So we'd get explosive movement and a visual style like this:</div>
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Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-25300684618993267352013-06-17T18:43:00.000-07:002013-10-05T22:58:15.853-07:00Project Loon<img height="426" src="http://techcapsule.com/wp-content/uploads/2013/06/google-project-loon.jpg" width="640" /><br />
Google just announced project Loon (<a href="http://googleblog.blogspot.com/2013/06/introducing-project-loon.html">Google Blog</a>, <a href="http://www.google.com/hostednews/afp/article/ALeqM5jzP2DG8WdyTFsRBXkX5IHRDod8UA?docId=CNG.1e0cb853eae78a4ee2a211df3413fa9a.01">AFP article</a>, and <a href="http://www.wired.com/business/2013/06/google_internet_balloons/">Wired article</a>). This is a scheme to provide internet access to folks in the southern hemisphere from high altitude balloons. Short take: they can steer the balloon, which is potentially the required gamechanger, the balloon is too big for their stated payload, and it'll need to get bigger if they want to build a global WiFi hotspot.<br />
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This is Google's second try at the southern hemisphere problem. In 2008 they helped start <a href="http://en.wikipedia.org/wiki/O3b_Networks,_Ltd.">O3b Networks</a>, which is attempting to launch a low earth orbit satellite constellation that would provide broadband access.<br />
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I'll start with a small point. Something is odd about the size of the balloon. The stated payload is 10 kg and the stated balloon is 15 meters in diameter, 3 mil thick polyethylene, and operates at 60,000 feet. That's too big a balloon for that payload.<br />
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The stated balloon envelope will weigh about 20 kg. So, they'd need about 30 kg of lift, which is about 30 m<sup>3</sup> of helium at standard temperature and pressure. But at 60,000 feet, the ambient density is around 100 g/m<sup>3</sup> and helium density is around 14 g/m<sup>3</sup>. So that's around 360 m<sup>3</sup> of volume. Google's 15 meter balloon holds 1767 m<sup>3</sup> and is sized to pick up something a lot bigger.<br />
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So, I'm guessing they actually want to lift something more like 100 to 150 kg. The helium to fill that is around $1300, the balloon is another $1500 in quantity, and the payload will be around $2k (but see below).<br />
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I wondered if they'd lose helium fast. It turns out, no. According to <a href="http://lpc1.clpccd.cc.ca.us/lpc/tswain/permeation.pdf">this table</a>, the helium permeability of polyethylene is 5.3e-8 cm^2/sec. The 'Loon probably has 235 m^2 of 75-micron-thick polyethylene, and so leaks 1.4 m^3/day. I'm surprised at how small that is... sounds like they could stay up for a year if the balloon is fully inflated and residence was limited by leakage. My guess is that time aloft will be limited by ultraviolet breakdown of the polyethylene and by wind shear occasionally ripping the things apart.<br />
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Assuming that ground terminals require a line of sight to the 'Loon at least 10 degrees above the horizon, each 'Loon covers a circle 200 km in diameter. Uniformly covering the whole earth would take 16,300 balloons. But they aren't going to cover the whole earth, and they had better not cover it uniformly.<br />
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The first big rollout, if it ever happens, will be over the <a href="http://en.wikipedia.org/wiki/Hadley_cell">Hadley cell</a> between 30 and 60 degrees south of the equator, and will cover primarily Australia, New Zealand, Argentina, South Africa, Chile, and Uruguay. They'll need around 3000 balloons to get complete coverage. The second big rollout will be over the Hadley cell between the equator and 30 degrees south, will require 4000 balloons, and will primarily cover Indonesia and Brazil. There will be major objections to these overflights in all the affected countries, and I'm not sure how Google will try to overcome those. But covering 1 billion people for $15m is pretty awesome.<br />
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The next logical rollout would be over the Hadley cell between the equator and 30 N. Once again, it would take 4000 balloons and cover India, the Philippines, most of central Africa, everything from Columbia to central Mexico. I just can't imagine this ever being accepted by governments with the ability to shoot down unwanted overflying balloons. The next Hadley cell north gets China and the US and is even less politically feasible.<br />
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The 'Loon has a proprietary link to the ground stations. Why not WiFi? The problem is that a single 'Loon will often cover 100,000 cellphones, each with a WiFi endpoint. Without some way to separate all those signals, the 'Loon will just see noise. A proprietary link allows Google to throttle the number of simultaneously transmitting terminals, and add coding gain, to get enough signal to noise ratio to communicate over dozens of km. Basically, the proprietary link is a way to shake the tree and see how governments react to a potentially uncensorable global ISP.<br />
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The better solution, the one I'm sure the Google engineers would love to implement, would be to put 802.11ac on the 'Loon. 802.11ac is the next-generation wireless Ethernet standard, and it will be on all smartphones in two years. Crucially, the standard protocol requires the handsets give the access point the feedback necessary for the access point to use phased array antennas to form beams. Those beams have two big consequences.<br />
<ul>
<li>The beams let the 'Loon capture more of the energy transmitted from the handset. A 6 m diameter phased array should capture enough energy from a cellphone at 40 km to enable 2-3 Mb/s transmission. I don't know that 802.11ac has a LDPC code that lets it go that slowly, but if not, Google may be able to require that Android handsets implement an additional optional royalty-free code.</li>
<li>The beams let the 'Loon distinguish between tens of thousands of handsets simultaneously. A 6 meter diameter phased array could implement cells on the ground 250 m diameter (right under the balloon) to 500 x 1000 m (far away from the balloon). This density isn't going to let folks in Cape Town watch HDTV via YouTube, but it'll handle email and web surfing just fine.</li>
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It's interesting to think about the parallels between this idea and the 1990s idea of having a constellation of low earth orbit satellites providing broadband access. At least <a href="http://www.itu.int/newsarchive/wtpf96/fact.html">five different schemes were proposed</a>. Iridium and Globalstar, both providing cellphone coverage, were actually built, and both went broke. Teledesic, backed by Bill Gates, Paul Allen, and Saudi prince Alwaleed bin Talal, got canned before it launched it's constellation. The problems with all these schemes were:<br />
<ol>
<li>The handsets were bulky and heavy because the satellites were 400 km up and 1000 km away. 'Loon cuts the range by more than an order of magnitude, which cuts the antenna size on both the access point (balloon) and handset by an order of magnitude.</li>
<li>The constellations required custom handsets. 'Loon has this problem too but 802.11ac is a path to a solution.</li>
<li>The access point hardware went on satellites which are expensive and hard to maintain. The balloons should be easier to maintain... than satellites. Though it's better than satellite constellations, I'd still count this issue against 'Loon.</li>
<li>The orbital geometry meant that coverage was concentrated near the poles, where there aren't many people. 'Loon does not have this problem.</li>
<li>The schemes required access point hardware sufficient to cover the entire earth, but only provided value where there were customers. 'Loon has this problem even worse than Teledesic. The Earth as a whole is about 30% land, but the southern hemisphere is 19% land. Worse yet, only 12% of the world's population lives in the southern hemisphere. This problem can kill 'Loon.</li>
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There are currently two broadband LEO constellations in the works. O3b, as mentioned above, and <a href="http://en.wikipedia.org/wiki/COMMStellation">COMMstellation</a>. I don't see how either has fixed the problems that sunk Teledesic et al.<br />
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<img src="http://www.fiddlersgreen.net/aircraft/NASA-Helios/IMAGES/NASA-Helios-Solar-Powered-Aircraft-Inflight2.jpg" /><br />
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There has also been a bunch of work on broadband from <a href="http://en.wikipedia.org/wiki/High-altitude_platform">High Altitude Platforms</a>. <a href="http://arstechnica.com/uncategorized/2005/10/5466-2/">Balloons</a> have been considered before, <a href="http://en.wikipedia.org/wiki/NASA_Helios">as have</a> <a href="http://en.wikipedia.org/wiki/Boeing_Phantom_Eye">high altitude</a>, <a href="http://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk">long endurance</a> <a href="http://www.avinc.com/downloads/GO-01_AV_GO_SkyTower_Web_.pdf">aircraft</a>, and <a href="http://en.wikipedia.org/wiki/Stratellite">interesting</a> <a href="http://defense-update.com/products/i/isis_hale_280409.html">hybrids</a> between the two. In the late 90s, <a href="http://www.angelcorp.com/">Angel Technologies</a> was going to fly a Rutan-designed aircraft in the stratosphere, carrying a phased array broadband access point. Aircraft can carry larger payloads (Halo could carry 1 ton), provide more power (Halo could provide 20 kilowatts), and can keep station over populated areas. Stationkeeping fixes problem #5 above, and is a huge deal.<br />
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'Loon may have a new answer to problem #5. They can steer. Fast forward to 1:11 in this video.<br />
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Steering is a big difference from satellites. Stratospheric winds will carry the 'Loons eastward around the globe, but if they can steer north-south while that is happening, they may be able to crowd the 'Loons over denser populations, and scoot across the oceans on the jet stream. Steering could dramatically reduce the number of 'Loons needed.<br />
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Technology developments to watch for:<br />
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A solar power array that faces nearly sideways, steered toward the sun with fans or something. Google is going to need this for the first big rollout, since the sun will not be more than 20 degrees above the horizon for most of the winter, and the grazing angle will kill their panel efficiency.<br />
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An ASIC that enables a 802.11ac access point to handle 1000 transceivers in less than 5 kilowatts. They are going to need this chip for the last forseeable rollout, the one that interfaces directly to cellphones and turns Google into a global ISP for Brazil and Indonesia at least. The ASIC is required because this generation 'Loon will be constrained by power. Power requires big solar arrays and batteries to get through the night, and those require a bigger, stronger balloon.<br />
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A balloon-to-balloon optical link consisting of multiple small gimbal-stabilized telescopes, perhaps two inches in diameter, to relay the photons between 10 gigabit ethernet fiber optic transceivers. I've wanted to see this technology for years, but the killer app hasn't shown up yet, because at ground level the weather would frequently disrupt any link. At 60k feet that shouldn't be a problem. They'll need this technology for that last big rollout. I don't think radios are going to work well enough.<br />
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As a camera nerd, I can't help but note the temptation to put a 2 kg camera on each 'Loon. You'd get something like hourly coverage of everywhere at 12 inch resolution, and real-time video coverage of smaller targets (like traffic accidents) as well. There is a real market for that... SkyBox Imaging just got $90m in venture capital to address it. This imagery, piped into Google Maps/Earth, would provide the live view of the entire earth that everyone already expects to be there.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-37700249672637663862013-04-19T11:18:00.002-07:002015-06-18T12:33:04.069-07:00Optical Bar Cameras<div class="separator" style="clear: both; text-align: center;">
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[Update: I'd like to thank Phil Pressel, John Gregor, and Gordon Petrie for their corrections to this post. The changes required have been so extensive I have not marked them.]<br />
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[Update 2: Phil Pressel just released his book Meeting the Challenge: The Hexagon KH-9 Reconnaissance Satellite (get it at <a href="http://arc.aiaa.org/doi/book/10.2514/4.102035">AIAA</a> or <a href="http://www.amazon.com/Meeting-Challenge-Hexagon-Reconnaissance-Satellite/dp/1624102034/ref=sr_1_2?ie=UTF8&qid=1379999025&sr=8-2&keywords=meeting+the+challenge">Amazon</a>). I've ordered it and will post a review after I get it.]<br />
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From 1957 to 1965, a high tech startup called <a href="http://en.wikipedia.org/wiki/Itek">Itek</a> made the world's most sophisticated satellite reconnaissance cameras for a single customer -- the CIA. The company has a fascinating subsequent history, as they ended up building cameras for Apollo and Viking. Eventually they ended up building the DB-110 reconnaissance pod, which I'll do a blog post on some day.<br />
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Merton Davies at RAND <a href="http://www.rand.org/content/dam/rand/pubs/reports/2007/R3692.pdf">apparently originated</a> the idea of using a spinning camera mounted on a spin-stabilized satellite to take panoramic shots with a narrow-angle lens. Amrom Katz passed the concept to Walter Levinson at Boston University Physical Research Laboratory (BUPRL). Levinson refined the idea to that of using an oscillating lens, for use in the HYAC-1 panoramic camera in Air Force high altitude reconnaissance balloons. Itek, just a few weeks after incorporation in late 1957, bought BUPRL, which was developing the HYAC-1 panoramic camera to take pictures from high altitude balloons.<br />
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Soon after, the CIA contacted Itek to discuss the camera requirements for the first spy satellites. All of these initial satellites came to use the rotating panoramic camera. I think this is the KH-4A or KH-4B Corona.<br />
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Itek also built versions of these cameras for use in the U-2 and SR-71 aircraft, in which they were called the OBC (Optical Bar Camera, named for the appearance of the field of regard on the ground). These were first used in the 1960s and are still in use today. Here is an Itek Optical Bar Camera that goes in the nose of an U-2:<br />
<img src="http://images.defensetech.org/wp-content/uploads/2011/03/Optical-Bar-Camera1.jpg" height="427" width="640" /><br />
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Take a look at the big, wide blue bar under the airplane. That's what a single frame of the camera shot. It's huge. I've heard that this "bar" looking frame was why they called it the optical bar camera. However, the NRO's Hexagon documentation refers to the rotating optical assembly (what in many cameras is called the "Optical Tube Assembly") as the optical bar.<br />
<img src="http://www.wvi.com/~sr71webmaster/sensor605.jpg" height="458" width="640" /><br />
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After a string of successful programs, requirements racheted up and tensions grew between NRO and CIA over the next program, Fulcrum. Early on, Itek was contracting with both the NRO and the CIA on competing projects. Itek pulled out of the CIA's project, and some combination of the NRO and the CIA took all their (government-owned) work and gave the job to Perkin-Elmer. When the dust settled the project was renamed Hexagon. Perkin-Elmer built the KH-9 Optical Bar Camera with their own design rather than Itek's, as they didn't think the Itek design would work. Here is a look into the aperture of the KH-9 Optical Bar Camera.<br />
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<img src="http://media.cmgdigital.com/shared/lt/lt_cache/thumbnail/960/img/photos/2012/05/06/3a/41/ddn032112spysatell_1102259a.jpg" height="408" width="640" /></div>
<br />
The Itek OBCs in the U-2, SR-71, and Apollo spacecraft all had a rotating structure called the roller cage, which I suspect was fixed to the rotating camera. The Perkin-Elmer design in the KH-9 deleted the roller cage and the rotating fold mirror inside it, and instead had a servo controlled twisting platen.<br />
<br />
Here is a comparison of various optical bar cameras built up to 1971 (the launch of the first KH-9).<br />
<br />
<table><tbody>
<tr><th></th><th>KA-80<br />
(U-2/SR-71/<a href="http://history.nasa.gov/afj/simbaycam/itek-pan-camera.htm">Apollo</a>)</th><th>(U-2/SR-71)</th><th>(<a href="http://www.nro.gov/history/csnr/gambhex/Docs/Critical%20to%20US%20Security.pdf">KH-9</a>)</th></tr>
<tr><td>Focal length</td><td>610 mm (24 inches)</td><td>760 mm (30 inches)</td><td>1524 mm (60 inches)</td></tr>
<tr><td>Aperture</td><td>174 mm (f/3.5)</td><td>218 mm (f/3.5?)</td><td>508 mm (f/3.0)</td></tr>
<tr><td>Cross-track Field of View</td><td>108 degrees</td><td>140 degrees</td><td>120 degrees</td></tr>
<tr><td>Film width</td><td>127 mm (5 inches)</td><td>127 mm (5 inches)</td><td>168 mm (6.6 inches)</td></tr>
<tr><td>Film length</td><td>2005 m (6500 feet)</td><td>3200 m (10500 feet)</td><td>70,000 m (230,000 feet)</td></tr>
<tr><td>Format</td><td>114 x 1073 mm</td><td>114 x 1857 mm</td><td>155 x 3190 mm</td></tr>
<tr><td>Film resolution</td><td>3.7 micron</td><td>3.7 micron</td><td>1000:1 contrast: 3.7 micron<br />
1.6:1 contrast: 7.4 microns</td></tr>
<tr><td>Depth of focus</td><td>+/- 13 microns</td><td>+/- 13 microns</td><td>+/- 11 microns</td></tr>
<tr><td>Format resolution</td><td>31k x 290k = 9 Gpix</td><td>31k x 502k = 15 Gpix</td><td>42k x 862k = 36 Gpix</td>
</tr>
<tr><td>Frames</td><td>1650</td><td>1640</td><td>21,000</td>
</tr>
<tr><td>Nominal Altitude</td><td>24.4 km (80k feet)</td><td>24.4 km (80k feet)</td><td>152 km (82 nm)</td></tr>
<tr><td>Center ground resolution</td><td>14.8 cm</td><td>11.9 cm</td><td>37 cm</td></tr>
<tr><td>Swath</td><td>67 km</td><td>134 km</td><td>555 km</td>
</tr>
<tr><td>In-track field of view, center</td><td>4.55 km</td><td>3.66 km</td><td>15 km</td><td></td></tr>
<tr><td>Nominal overlap</td><td>55%</td><td>55%</td><td>10% (each camera)</td></tr>
<tr><td>Area collected</td><td>226k km<sup>2</sup></td><td>362k km<sup>2</sup></td><td>2x 80m km<sup>2</sup></td></tr>
<tr><td>Nominal ground velocity</td><td>1000 m/s</td><td>1000 m/s</td><td>7,800 m/s</td></tr>
<tr><td>Cycle time</td><td>2 sec</td><td>1.65 sec</td><td>1.73 sec</td></tr>
<tr><td>Film velocity at slit</td><td>1.9 m/s</td><td>2.9 m/s</td><td>5.5 m/s</td></tr>
<tr><td>Maximum slit size</td><td>7.62 mm</td><td>12? mm</td><td>22? mm</td></tr>
<tr><td>Max exposure time</td><td>4 ms</td><td>4? ms</td><td>4? ms</td></tr>
</tbody></table>
<br />
Take a look at the area collected by the KH-9. The Soviet Union was a big place: 20m km<sup>2</sup>. Each of the four film re-entry capsules could return the entire USSR, in stereo, with plenty of side overlap and margin for images fouled by clouds. Typically they chose to take more frames with smaller swaths (90 degrees or 60 degrees) to get higher average resolution, which brought down the total take somewhat to around 60 million km<sup>2</sup>.<br />
<br />
My resolution numbers up there are slightly inflated. The film used could only eke out 130 lp/mm when given the maximum possible amount of contrast, such as would be seen at a shadow line. For finding something like paint on a road they were about half that. Pixellated sensors have a much more drastic cliff, of course. So the e.g. KH-9 resolution above might be compared to anything like a 20 to 30 gigapixel camera today. I'll note that I don't have any of those to suggest.<br />
<br />
There are two big concepts here that I think are important. The first is the mechanical and logistical difficulties of using film. Below I've spelled out some of the details. The second is that despite these headaches, until very recently, film has been superior in many ways to electronic sensors for massive survey work.<br />
<br />
The basic problems with using film stem from the fact that the sensor surface is a thin, pliable, moving, relatively inexpensive object that has to be held within the camera with very high precision. There must have been several problems associated with getting the film aligned within +/- 11 microns of the lens's focal plane. Among other things, the machines resemble Van de Graf generators, and so the film is subject to static electricity buildup and discharges, along with heating that tends to make it even more pliable and sticky. To reduce the static buildup, many of these cameras slid the film over surfaces with hundreds of pores lifting the film with pressurized air.<br />
<br />
I think the Itek designs spun the entire optical assembly at a constant rate. The entire spinning optical assembly is inside a gimbal which rocks back and forth 1.6 degrees in each cycle. The rocking motion accomplishes forward motion compensation, so that the sweep of the slit across the ground is orthogonal to the direction of flight. This compensation ensures that the motion of the image on the film moves almost exactly with the film, and there is no blurring in the direction of flight during longer exposures. This rocking motion must have required fairly large torques, and I'm sure this is one of the things that the Perkin-Elmer folks balked at when considering the Itek design in space. Note that a constantly rotating camera sweeps at the outer edges faster than at the center, so the forward motion compensation probably had to vary it's rate of rocking as it went to compensate.<br />
<br />
<a href="http://history.nasa.gov/afj/simbaycam/pan3small.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="http://history.nasa.gov/afj/simbaycam/pan3small.jpg" /></a><br />
Here is a diagram which shows how the film was wrapped around the roller cage in the Itek designs. As the optical assembly (including the roller cage) twists counterclockwise, the film is transported clockwise.<br />
<br />
However, even with a constant spin rate, the film does not transport at a constant rate. For instance, in the SR-71 OBC, a frame is exposed for 640 ms, during which time the film rips around the roller cage at 2.9 meters per second (that's what the rollers see). For the next second, the film advances at just 1 meter per second, so that the frame boundary going across the top of the roller cage can meet up with the slit going around the bottom. Because of the speed change, many of the freewheeling rollers on the roller cage will contact unexposed film coming from the framing roller with a tangential speed difference of 1.9 meters per second. As each freewheeling roller changes speed to match the film, it seems to me it would tend to scuff the film. I'm sure they made sure to make those rollers as lightweight as possible to reduce their rotational momentum.<br />
<br />
Note the unlabeled slit after the second mirror right next to the film wrapped around the roller cage. Only the portion of the film after this in the optical chain has light on it, so this is the only spot that must be held accurately. I don't really know how it was done, since every moving belt of material that I've even seen has vibrated. They may have had a glass reseau plate that the film slid across. Sliding film across glass at 2.9 meters per second seems like an excellent way to scratch one or both. I have no evidence for it yet, but this seems like a good application for the compressed air film handling scheme.<br />
<br />
The Itek forward motion compensation gimbal also took out airplane pitch motions. Airplane roll motions were taken out by varying the optical tube roll rate. That's easy enough (it doesn't require torque), but the film rate supplied to the roller cage assembly in the back also had to change to match.<br />
<br />
That last diagram gives a pretty good clue to another challenge in this design -- film curvature. Although I've not found any labelled dimensions, it looks like the roller cage in the Itek designs was about 300 mm in diameter. The design of the roller cage really had me puzzled for a while, because the film transport path is cylindrical, but the film being exposed by the slit has to be flat. I finally figured it out when I took a good look at this photo of the Apollo OBC (also made by Itek):<br />
<img src="http://history.nasa.gov/afj/simbaycam/pan9.jpg" height="605" width="640" /><br />
<br />
The roller cage is a cylindrical cage of ROLLERS! Duh! As the film passes between the rollers, it's locally flat, and that's how they keep the film surface matched to the lens focal plane. Here's a 5x blowup of the roller cage in the picture above. It looks like the rollers are packed together as close as they can get in order to minimize the polygonal variation in film distance from the center of roller cage rotation. I think this variation leads to a (small) variation in film speed at the exposure site.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbZ_pyZ7aq5Gp6Vd2C5uaurXYcav6AjtwtiIdf21vYWQav7P3HGvlbSwL4c-9ZlQUjLy6cbOehrDEjrCM0QHknGTRKRRttTb7elhjzLUyhDOxv036g2urto5c4a37zrgaSV-w/s1600/Roller+cage.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbZ_pyZ7aq5Gp6Vd2C5uaurXYcav6AjtwtiIdf21vYWQav7P3HGvlbSwL4c-9ZlQUjLy6cbOehrDEjrCM0QHknGTRKRRttTb7elhjzLUyhDOxv036g2urto5c4a37zrgaSV-w/s640/Roller+cage.png" width="640" /></a></div>
There should be a spot in the roller cage where there aren't any rollers, and the film becomes planar for a while. This spot would be over the exposure slit. In the Apollo OBC pictured here, the gap between the rollers must be at least 7.6mm, and given the orientation of the lens at the top it should be on the back side of the roller cage that we don't see here.<br />
<br />
<br />
The film is pulled taut around the stuttering, bucking and twisting roller cage with an assembly that looks like the following. During the exposure film is pulled around the roller cage at 5.7 meters/second. Here's the film path:<br />
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<a href="http://history.nasa.gov/afj/simbaycam/pan6.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://history.nasa.gov/afj/simbaycam/pan6.jpg" height="226" width="320" /></a></div>
If the tension on the film is too small, small irregularities in it's "set" curvature will make it lift off as it goes around the roller cage, and small patches of the film will lift away from the cage. With a +/- 11 micron depth of focus, it doesn't take much lift off to make a problem. If the tension is too high, the film will wrinkle longitudinally.<br />
<br />
<br />
The Perkin-Elmer design did not have the roller cage or the gimbal. Instead, they had a twisting platen assembly at the focal plane. This would twist back and forth through 130 degrees as the optical bar rotated through 360 degrees. The two were nearly locked together through the 120 degrees of rotation that were used for exposure.<br />
<iframe allowfullscreen="" frameborder="0" height="315" src="http://www.youtube.com/embed/LQq9KcEw7nk?rel=0&#t=5m22s" width="560"></iframe><br />
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Because the Perkin-Elmer design has no rocker gimbal doing forward motion compensation, and the optical assemblies rotate at constant speed, the sweep is faster at the edges than in the center, and the area swept in each frame is slightly S shaped. They may have splayed the roll axes of the optical bars to get first order forward motion compensation, but this doesn't change the S shape. To keep the image from smearing across the film, the KH-11 has to keep the slit perpendicular to the motion of the slit across the ground, accounting for the changing sweep rate versus spacecraft velocity, as well as the rotation of the Earth, which is 6% of the spacecraft velocity at the equator.</div>
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<br /></div>
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This is why the twisting platen in the KH-11 is servo locked to the twisting optical assembly. They have to vary the relative twist of the two a little bit to keep the projected slit perpendicular to it's projected motion.</div>
<br />
After the picture was shot the film sat around for a month in a temperature and humidity controlled environment, and then was dropped, recovered, and developed. There was a lot of opportunity for the film to shrink differentially. All the mechanical twisting, as well as film shrinkage, must have made photogrammetry a nightmare.<br />
<br />
The <a href="http://en.wikipedia.org/wiki/Sunny_16_rule">Sunny 16 rule</a> says that you can properly expose ISO 100 film in bright daylight conditions with a f/16 lens with a 10 ms exposure. The KH-9 used mostly monochrome Kodak 1414, which has an Aerial Film Speed of 15, which I think is equivalent to ISO 38. In full sun a 1 ms exposure at f/3 would have worked fine. On the Apollo OBC that corresponds to a 1.9mm wide slit. They did have exposure control hardware, and it looks like they could exposure for two stops dimmer than full sun. They might have also stopped down from that, in order to avoid blowouts over ice.<br />
<br />
<hr />
<br />
At this point, I'm sure those of you who have worked with digital sensors are feeling pretty smug. But consider how wonderful film was for capturing and returning large amounts of imagery.<br />
<br />
Each of the four re-entry vehicles on the KH-9 would bring back 5,000 36 gigapixel images. If somehow compressed to 1 bit per pixel, that would be about 20 terabytes. These days that's about 10 hard disks, and would take about three months to downlink at a constant 25 megabits per second. Since they were returning these re-entry vehicles every few months, a modern downlink is only barely adequate. It has only been in the last 10 years or so that disk drive capacities have become high enough to fit the data into the payload of one of those re-entry vehicles -- 30 years after the KH-9 was originally deployed.<br />
<br />
In 1971, the area of film actively integrating photons in the KH-9 was 155 mm x 15 mm. The <a href="http://www.teledynedalsa.com/imaging/products/cameras/hs-line-scan/piranha-hs/HS-S0-12K40/">largest, fastest TDI CCD sensors commercially available in 2013</a> are 64 mm x 1.3 mm. The pixels on these are 5.2 microns rather than 3.7 as on film. The smaller integrating length (1.3 mm versus 22 mm) gives a maximum exposure time of 240 microseconds, which is smaller than the 2 milliseconds we would prefer. 155 mm x 10 mm CCDs with 3.7 micron pixels are not commercially available, but could probably be custom made.<br />
<br />
Another issue would be the readout rate. A fast TDI in 2013 reads out lines at 90 KHz. The KH-9 was exposing film in the roller cage at 5.5 meters/second, which corresponds to a line readout rate of 1.5 MHz. This could be achieved with a custom built TDI sensor maybe 5 years ago. It would require 1300 ADCs running at 45 MHz, which would burn a lot of power. This might be possible with interesting packaging.<br />
<br />
The capture rate of the KH-9 was so enormous it completely overwhelmed the ability of the photointerpreters at the CIA to examine the photographs. It's only recently that computers have gotten large enough to store and process imagery at this volume, and it's not at all clear that anyone has yet developed algorithms to find the "unknown unknowns" in a bunch of raw imagery. I think they call this "uncued image search".<br />
<br />
To my knowledge the U.S. never again fielded a spysat with the ability to survey major portions of the earth at high resolution. Later Keyhole satellites appear to have concentrated more on taking valuable single shots at higher resolution (7 cm GSD), and on having the orbital maneuverability to get those shots. I think the intelligence folks lost interest in survey satellites when it became clear that they couldn't take advantage of the comprehensive coverage which was their primary feature. It's kind of ironic that the very problem that Itek was founded to solve (managing the huge volume of survey photography) ended up being a major reason why satellites with survey capacity made possible by Itek's cameras faded away. It's fascinating for me to see what has become of this problem.<br />
<br />
Brian McClendon is on record as saying that Google has 5 million miles and 20 petabytes of Street View imagery. That's the processed imagery, not the raw take. The KH-9 raw take that overwhelmed the CIA photointerpreter capacity 30 years ago was less than 1% of what Google Street View shot. Unlike the KH-9 imagery, most of which I suspect has never been looked at, every one of the Street View panoramas has been seen by a real user. And Google is hardly the only organization using Big Data like this. The consumption problem that the CIA and NRO never solved has been utterly crushed by organizations with entirely different goals. (Granted, uncued search remains unsolved.)<br />
<br />
Now that Big Data has caught up with the photo throughput of digital satellites, it's fun to think about what could be built with modern technologies. But that's probably best saved for another post.<br />
<br />Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com6tag:blogger.com,1999:blog-8628325.post-20935800175542531242013-03-19T17:49:00.000-07:002013-03-19T17:49:29.212-07:00R7 baffle being laser cut<div class="separator" style="clear: both; text-align: center;">
<object width="320" height="266" class="BLOGGER-youtube-video" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0" data-thumbnail-src="http://img.youtube.com/vi/T_PA9eUd5tA/0.jpg"><param name="movie" value="http://youtube.googleapis.com/v/T_PA9eUd5tA&source=uds" /><param name="bgcolor" value="#FFFFFF" /><param name="allowFullScreen" value="true" /><embed width="320" height="266" src="http://youtube.googleapis.com/v/T_PA9eUd5tA&source=uds" type="application/x-shockwave-flash" allowfullscreen="true"></embed></object></div>
<br />
Check it out! This is the baffle for the R7 StreetView camera. The final apertures are being cut with a laser. These apertures have to line up with the view cone of the cameras fairly tightly, in order to clip off a ghost reflection in the lens that I missed during optical design. The ghost only hits the sensor when the sun is in a 5 degree wide band just outside the field of view. I suspect it's a fairly complex internal reflection path, since a simple double bounce ghost ought to sweep through the center of the lens as the sun does.<br />
<br />
I had the idea of welding the whole baffle together and then as a final operation cutting the apertures, with the hope that the metal would stop moving around once we'd cut smaller apertures and finished welding. It didn't really work out perfectly. There was a fair bit of tolerance stackup between the internal lenses and this external baffle. Also, the baffle mounted to 8 screws, and those 8 points would tend to get significantly out of alignment, so that the baffle shape that you ended up with depended on what order you tightened the screws. As a result we had to open up some extra margin on the baffle openings. I know for a fact that the sun can leak into the corners. After a quick check, I can't find any examples of the ghost, though, so the baffle is doing a decent job.<br />
<br />
R7 at work:<br />
<br />
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<a href="http://bloximages.chicago2.vip.townnews.com/host.madison.com/content/tncms/assets/v3/editorial/1/8c/18c1875e-bfa8-11e0-939b-001cc4c002e0/4e3c5d8730375.image.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="393" src="http://bloximages.chicago2.vip.townnews.com/host.madison.com/content/tncms/assets/v3/editorial/1/8c/18c1875e-bfa8-11e0-939b-001cc4c002e0/4e3c5d8730375.image.jpg" width="640" /></a></div>
<br />
R7 at play. Hi Ryan! Note the ears on top. Those are the twin GPS antennae... the way I intended all R7s to be.<br />
<br />
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<a href="http://tctechcrunch2011.files.wordpress.com/2012/10/trekker-and-android.jpg?w=640&h=426" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="426" src="http://tctechcrunch2011.files.wordpress.com/2012/10/trekker-and-android.jpg?w=640&h=426" width="640" /></a></div>
<br />Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com1tag:blogger.com,1999:blog-8628325.post-61713575591478773412013-02-15T01:55:00.000-08:002013-02-27T10:16:17.136-08:00Mixing Clouds<span class="inline_editor_value">First, let me recommend a great book: <span class="qlink_container"><a class="external_link" data-tooltip="attached" href="http://www.amazon.com/Clouds-Glass-Beer-Experiments-Atmospheric/dp/0486417387/ref=sr_1_1?s=books&ie=UTF8&qid=1360566754&sr=1-1&keywords=bubbles+in+a+glass+of+beer" target="_blank">Clouds in a Glass of Beer: Simple Experiments in Atmospheric Physics: Craig F. Bohren: 9780486417387: Amazon.com: Books</a> It's short and is composed of many short chapters, each with an experiment and an explanation. Chapter 5, mixing clouds, has always bugged me, and in response to a Quora question I finally did the math on the white stuff coming out of a kettle on the stove.</span><br /><br />The
clear stuff coming out of your kettle spout is 100% vaporized water.
(I'll sidestep pedantic discussions of the meanings of "steam" and
"water vapor".) It quickly entrains the cooler air around the kettle
and mixes with it, forming a mixing cloud, which you can see and most
folks refer to as "steam".</span><br />
<div>
<img class="qtext_image zoomable_in zoomable_in_feed" master_h="358" master_src="https://qph.is.quoracdn.net/main-qimg-12826dba53d3444fe0503f163437e161" master_w="498" src="https://qph.is.quoracdn.net/main-qimg-78f3cc007d16af90482fe4a626da43bc" /></div>
The
mixing cloud forms because the relationship between the vapor pressure
of water and temperature is not linear but rather curved. It's the red
set of dots above. This is really important, so take a moment with the
idea. As the temperature of the water in the kettle rises from 20 C
(room temperature) to 100 C (boiling), the pressure component of the
air/vapor mix above it due to the vapor rises from something quite tiny
to 1 bar (standard atmospheric pressure).<br />
<br />
Now let's dilute that
ejected 100% water vapor with some dry air at 20 C. The mixed result is
cooler than 100 C and has a lower vapor pressure than 1 bar (because
not all the stuff is water vapor any more). Once you've accounted for
the different heat capacities of water vapor and water, and the thermal
expansion or contraction of the constituents, you get the blue curve
above. You read the curve like so: if I mix some amount of 20 C dry air
into some 100 C water vapor, so that the result is 60 C, then it's
partial pressure of water vapor is 0.29 bar. At least, that would be
the partial pressure if all the water was in vapor form.<br />
<br />
The
really neat thing here is that the blue curve is ABOVE the red curve all
the way down to 26 degrees C, which happens to correspond to 95.8% dry
air and 4.2% water vapor. At any mixing ratio between this and 100% water vapor, there
will be more water in the mixing cloud than can be in vapor phase, and
some will be in the form of very tiny (micron) water droplets. However,
once the mixing cloud is sufficiently diluted with dry air, there will
be less water vapor in it than the maximum that can be in vapor phase,
and all those tiny droplets with their huge surface air to volume ratio
will immediately evaporate.<br />
<br />
What this means is that the mixing
cloud grows to 23 times bigger than the pure water vapor expelled from
the kettle before it disappears.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-23957246441066207292013-01-30T22:27:00.000-08:002013-03-24T22:27:35.696-07:00Thousands of drones<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCfzrlEFNj3MuSZgvIKRgQ5yfxE0mUulQapbtPV6qG_Z1-va4H4AgQU32dD7VDWN-ZZROPdRwQZyolG327ZF5cFLjUZZaMuAn-noSHhpIaCJLRCIeC3yp9Xgh2mcH75JS-gng/s1600/Solar+RC+plane.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCfzrlEFNj3MuSZgvIKRgQ5yfxE0mUulQapbtPV6qG_Z1-va4H4AgQU32dD7VDWN-ZZROPdRwQZyolG327ZF5cFLjUZZaMuAn-noSHhpIaCJLRCIeC3yp9Xgh2mcH75JS-gng/s400/Solar+RC+plane.jpg" width="400" /></a></div>
<br />
Someone recently asked me if aerial survey could be accomplished with a swarm of tiny drone aircraft. Imagine foot-long planes made of styrofoam, carrying the camera, IMU, and GPS of a cellphone, minus the display, with a far larger battery for propulsion. How can this fail to be a cheaper way to survey large areas?<br />
<br />
I've worked on a drone program before, but that was with a gas-powered UAV weighing 25 kg empty with a 2 kg payload and a range of around 1100 km over an 6 hour flight, costing in excess of $50k. Operational costs were expected to be dominated by the cost of crashing. I can say confidently that these are not a cheap way to survey anything.<br />
<br />
In researching this blog post, I learned about solar-electric RC airplanes, which are a completely different kettle of fish. <a href="http://www.rcgroups.com/forums/showthread.php?t=572000">The Aphelion</a>, above, was built for under $500 (materials only) in Professor Mark Drela's MIT lab, and can fly at 5-6 m/s for as long as the sun is 6.5 degrees above the horizon, which is something like 8 to 12 hours a day. That puts the daily range around 150 km.<br />
<br />
Crucially, the whole airplane weighs 1300 grams distributed over a 3.3 meter wingspan. My guess is that a Cessna might survive an in-flight impact with one of these, and maybe even something a bit heavier.<br />
<br />
A survey drone version would be ruggedized for e.g. 1000 flights MTBF, would carry a 200 g camera payload and a 50g battery, would fly at 12 m/s, and cover 300 km during a day's flight. Higher speeds lead to more coverage and better survivability in higher winds, but also smaller wings and less solar power. The battery allows flight with intermittent solar coverage, due to clouds and building blockages.<br />
<br />
This range is not great. If a drone maintained 10 m/s from 9AM to 3PM, it would cover 216 km. For comparison, a King Air B200, which is something of a standard twin-turboprop airplane for aerial survey, flies at 140 to 150 m/s and can cover 1700 km in a morning.<br />
<br />
These drones are going to require an ultralight camera -- basically a cellphone camera. The camera scales surprisingly well, primarily because you are comparing cellphone sensors to huge custom CCDs used in e.g. Leica ADS80 aerial cameras, and of course the cellphone sensors are far better because they have far more engineering investment. Nowadays I would use an Aptina MT9F002 14-megapixel sensor with a 10mm lens, which will deliver 2 inch resolution from 1000 feet up. This will deliver a swath of over 200 meters. Because the drone will bounce around a fair bit, we'll need a very generous overlap between the imagery captured in one flight line and the next, so the flight pitch will be something like 150 meters. For comparison, an ADS80 camera in a B200 flies with a 1 kilometer flight pitch when shooting this resolution.<br />
<br />
Due to the close range and excellent sensor there is no need for a gimbal for the drone camera. I'd use a 400 microsecond exposure time. Combine that with the 140 microradian pixel field of view, and the camera can tolerate rolls and pitches of 25 to 50 degrees per second without excessive motion blur. I think even a little drone with very low wing loading can deliver that most of the time. If we shoot 94% forward overlap between frames (1 frame per second), which is possible because we are going so slowly, then if we lose a few shots due to motion blur we can afford to just drop them. We'll collect about 100 GB of data in 6 hours at that frame rate, which will be storable on a microSD card next year.<br />
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Now we come to the very bad news for this idea. The combination of low speed and small flight pitch means that we'll need something like 100 drones to replace a ADS80 in a B200. If you talk to R/C folks, you will find that they spend at least as much time fixing their aircraft as they do flying them. So those 100 drones are going to require an army of people to launch, recover, and repair them.<br />
<br />
The bottom line is that using drones instead of manned aircraft still seems like a bad idea... if you can use a manned aircraft. But here is how survey drones might turn out to be a really wonderful idea: If you can make the drone light enough that it just won't hurt anyone when it crashes, then you might be able to get permission to fly down city streets. THAT would rock, because you'd simultaneously solve a bunch of problems that a bunch of folks (Nokia/Navteq, TomTom/TeleAltas, Google) are spending hundreds of millions of dollars a year on today:<br />
<ul>
<li>You would be collecting street level imagery without having to wait for traffic. Much, much faster.</li>
<li>The native perspective of the cameras would be the one that people actually want. This is just my intuition, but my sense from working on Street View is that it was too damn slow and difficult to navigate. I think people want a raised perspective, but just not raised too much.</li>
<li>You would be collecting the sides of buildings at high resolution. Right now there is a major gap between street-level resolution (Google's Street View is 3mm resolution) and aerial resolution (Google's 45 degree view is 100mm resolution). That gap means that the sides of buildings don't match up well, which is a problem if, like Apple and Google, you want to deliver great looking 3D models of buildings.</li>
<li>Aerial obliques don't actually work in places like New York because the buildings are too tall compared to the street width. However, if you fly between the buildings, this is no longer a problem! This is a major issue now that over half the world's population (likely the wealthier half) live in cities.</li>
</ul>
<div>
I think it's a big stretch to imagine getting permission to fly your UAVs down city streets, and technically it would be a big challenge just to plan the routes... you'd probably end up needing to survey the city from high altitude first. It sure is fun to think about, though.</div>
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Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-30502906413239784172012-12-14T12:48:00.000-08:002012-12-14T12:50:05.490-08:00Cloud + Local imagery storageThe Department of Homeland Security has said that it wants imagery delivered in the cloud. Several counties and states have expressed the same desire. Amazon S3 prices are quite reasonable for final imagery data delivered, especially compared to the outrageous prices that imagery vendors have been charging for what amounts to a well-backed-up on-site web server with static content. I've heard of hundreds of thousands of dollars for serving tens of terabytes.<br /><br /><div>
Everyone wants the reliability, size, and performance scalability of cloud storage. No matter how popular your imagery becomes (e.g. you happen to have the only pre-Sandy imagery of Ocean City), and no matter how crappy your local internet link happens to be, folks all around the world can see your imagery. And many customers are more confident in Amazon or Google backups than their local IT backups.<br /><br />But everyone also wants the reliability of local storage. E911 services have to stay up even when the internet connection goes down. So they need their own local storage. This also helps avoid some big bandwidth bills on the one site you know is going to hammer the server all the time.<br /><br />So really, imagery customers want their data in both places. But that presents a small problem because you do want to ensure that the data on both stores is the same. This is the cache consistency problem. If you have many writers frequently updating your data and need transaction semantics, this problem forces an expensive solution. But, if like most imagery consumers you have an imagery database which is updated every couple of months by one of a few vendors, with no contention and no need for transaction semantics, then you don't need an expensive solution.<br /><br />NetApp has a solution for this problem which involves TWO seriously expensive pieces of NetApp hardware, one at the customer site and one in a solo site with a fat pipe to Amazon. The two NetApp machines keep their data stores synchronized, and Amazon's elastic cloud accesses data stored at the colo over the fat pipe. This is... not actually cloud storage. This is really the kind of expensive shoehorned solution that probably pisses off customers more than me because they have to write the checks.<br /><br />The right answer (for infrequently-updated imagery) is probably a few local servers with separate UPSes running Ceph and something like rsync to keep updates synchronized to S3. Clients in the call center fail over from the local servers to S3, clients outside the call center just use S3 directly.<br /><br />I feel sure there must be some Linux vendor who would be happy to ship the Nth system they've build to do exactly this, for a reasonable markup to the underlying hardware.</div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-71843165942797739902012-12-05T08:30:00.000-08:002012-12-24T18:00:28.899-08:00Dragonfly Eyes - the Wonders of Low Resolution<div class="separator" style="clear: both; text-align: center;">
<a href="http://blogs.discovermagazine.com/notrocketscience/files/2011/12/Blue-spotted-hawker-dragonf1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="243" src="http://blogs.discovermagazine.com/notrocketscience/files/2011/12/Blue-spotted-hawker-dragonf1.jpg" width="320" /></a></div>
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Continuing with the recent theme of analyzing both natural and man made cameras, I thought I'd analyze an insect eye in this post. In previous posts I've analyzed a <a href="http://ambivalentengineer.blogspot.com/2012/08/argus-is.html">gigapixel airborne security video camera</a> and the <a href="http://ambivalentengineer.blogspot.com/2012/08/hawk-eyed.html">eye of a raptor</a>. I'm working on analyses of the F-35's Distributed Aperture System as well as a really gigantic film camera for future posts.<br />
<br />
The picture above is of a blue-spotted Hawker dragonfly. This creature apparently catches its prey in midflight, so it's supposed to have big, high resolution eyes. According to John Patterson in <a href="http://blogs.discovermagazine.com/notrocketscience/2011/12/07/anomalocaris-sharp-eyes-predator/#.UL7OCoNZWiA">this Discover magazine article</a>, it has 28,000 lenses in each eye. Judging from the picture, those eyes are probably covering half of the possible 4*pi solid angle, so each tiny lens is covering a solid angle of 112 microsteradians. That would be Low Resolution to my mind. Critters like spiders and grasshoppers, with even smaller eyes, must be commensurately worse.<br />
<br />
To give some context, a human in bright light has a pixel field of view of 25 nanosteradians. You can see across your yard (70 feet) what the dragonfly can see from 1 foot. If it is going after an 8mm long house fly, it needs to close within 80 cm in order to get a full pixel on the target. At that range the house fly can probably <i>hear </i>the dragonfly, although I haven't analyzed that and insect hearing might also be much worse than human hearing. This dragonfly is not a long-range hunter like a bird, but rather an opportunist. I very much doubt it can pull off a high-relative-speed attack like a Peregrine falcon, which requires good angular resolution and gimbal stabilization.<br />
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Interestingly, the creature collects about the same amount of light per pixel that the human eye does. The entire creature is about 70mm long. Judging from the picture below, the eyes are probably 10 mm across. That means those little lenses are 53 microns across. On a bright day outside, your human pupils constrict to 3 mm, 55 times larger. But since the dragonfly's pixel field of view is 70 times bigger, it actually receives about 50% more light per pixel than you do.<br />
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<a href="http://australianmuseum.net.au/Uploads/Images/19931/Job17092_P1010015_big.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://australianmuseum.net.au/Uploads/Images/19931/Job17092_P1010015_big.jpg" width="320" /></a></div>
I used to be concerned that the tiny dragonfly lenses would cause diffraction blurring. Supposing for a moment that they look at green light, their Rayleigh criterion is about 12 milliradians, nicely matched to their pixel angular field of view of 10.5 milliradians. If the effective pupil of each lens is substantially smaller than the allotted space (low fill factor), then the dragonfly would have to use a shorter wavelength to avoid diffraction problems. It doesn't look like a big problem.<br />
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I don't think the dragonfly has to stabilize the scenery with it's neck. A dragonfly flying at 1 meter/second sees scenery 50 cm away to the side going by at 2 radians/second. To get less than 3 pixels of motion smear, it would have to integrate the exposure for less than 15 milliseconds. That's just a bit quick, so the creature probably sees some motion blur to the side, but not so much in front of it, since there is considerably less angular motion in the direction of flight.<br />
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<br />Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com1tag:blogger.com,1999:blog-8628325.post-81126568694130177512012-09-03T09:29:00.000-07:002012-09-03T09:29:00.308-07:00Red Rocks!<a href="http://www.red.com/learn/red-101/high-frame-rate-video">Here's an explanation</a> from RED about why high frame rate video is a good thing. They are right, and this is a great explanation with really impressive examples.Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-16981185622315243392012-08-27T08:30:00.000-07:002013-04-03T22:31:13.900-07:00ARGUS-IS<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipBtK9L7G4D65mNF6CBhMvLCXuVmOsotqH-LrVT7QqyfkxTtwQ06HDR4zwU7drfR-GLUKKFSuG5ZyochduUqtMYYLp5xABfKWv3e876N9VECbBpR71txr4g4GmoHvkqFDYxcg/s1600/argus-gigapixel-cameras.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="258" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipBtK9L7G4D65mNF6CBhMvLCXuVmOsotqH-LrVT7QqyfkxTtwQ06HDR4zwU7drfR-GLUKKFSuG5ZyochduUqtMYYLp5xABfKWv3e876N9VECbBpR71txr4g4GmoHvkqFDYxcg/s320/argus-gigapixel-cameras.jpg" width="320" /></a></div>
Here's an exotic high flying camera: ARGUS-IS. I've been trying to figure what these folks have been up to for years, and today I found <a href="http://144.206.159.178/ft/CONF/16415556/16415570.pdf">an SPIE paper</a> they published on the thing. What follows is a summary and my guesses for some of the undocumented details. [Updated 30-Jan-2013, to incorporate new info from a Nova documentary and a closer reading of the SPIE paper.]<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij4YlGMkyIdCen0aBsY0BTqwVb_QsGxKYJNmXZ-YH1swdQ0DYrX9i2MwLAdkjwd4_T0iKYuYPVhSJ37n2_-T_RBCTqoMQjpc2ntQyUZeo4dfr9Uxx3yiout0MRi7Th0Ang9-U/s1600/Vexcel+Ultracam+XP.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="195" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij4YlGMkyIdCen0aBsY0BTqwVb_QsGxKYJNmXZ-YH1swdQ0DYrX9i2MwLAdkjwd4_T0iKYuYPVhSJ37n2_-T_RBCTqoMQjpc2ntQyUZeo4dfr9Uxx3yiout0MRi7Th0Ang9-U/s320/Vexcel+Ultracam+XP.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Vexcel Ultracams also use four cameras<br />
with interleaved sensors</td></tr>
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<ul><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij4YlGMkyIdCen0aBsY0BTqwVb_QsGxKYJNmXZ-YH1swdQ0DYrX9i2MwLAdkjwd4_T0iKYuYPVhSJ37n2_-T_RBCTqoMQjpc2ntQyUZeo4dfr9Uxx3yiout0MRi7Th0Ang9-U/s1600/Vexcel+Ultracam+XP.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /></a>
<li>It looks like BAE is the main contractor. They've subcontracted some of the software, probably the land station stuff, to ObjectVideo. BAE employs Yiannis Antoniades, who appears to be the main system architect. The lenses were subcontracted out to yet another unnamed vendor, and I suspect the electronics were too.</li>
<li>Field of view: 62 degrees. Implied by altitude 6 km and object diameter 7.2 km.</li>
<li>Image sensor: 4 cameras, each has 92 Aptina MT9P031 5 megapixel sensors. The paper has a typo claiming MT9P301, but no such sensor exists. The MT9P031 is a nice sensor, we used it on the R5 and R7 Street View cameras.</li>
<ul>
<li>15 frame/second rate, 96 MHz pixel clock, 5 megapixels, 2592 x 1944.</li>
<li>It's easy to interface with, has high performance (quantum efficiency over 30%, 4 electrons readout noise, 7000 electrons well capacity), and is (or was) easy to buy from <a href="http://www.digikey.com/product-detail/en/MT9P001I12STC/557-1455-ND/2074134">Digikey</a>. (Try getting a Sony or Omnivision sensor in small quantities.)</li>
</ul>
<li>Focal length: 85mm. Implied by 2.2 micron pixel, altitude of 6 km, GSD of 15 cm. Focal plane diameter is 102mm. The lens must resolve about 1.7 gigapixels. I must say that two separate calculations suggest that the focal length is actually 88mm, but I don't believe it, since they would have negative sensor overlap if they did that.</li>
<li>F/#: 3.5 to 4. There is talk of upgrading this system to 3.7 gigapixels, probably by upgrading the sensor to the <a href="http://www.1stvision.com/cameras/sensor_specs/Aptina%20MT9J003.pdf">Aptina MT9J003</a>. An f/4.0 lens has an Airy disk diameter of 5.3 microns, and it's probably okay for the pixels to be 2.2 microns. But 1.66 micron pixels won't get much more information from an f/4.0 lens. So, either the lens is already faster than f/4.0, or they are going to upgrade the lens as well as the sensors.</li>
<li>The reason to use four cameras is the same as the <a href="http://www.microsoft.com/ultracam/en-us/UltraCamXpTechnical.aspx">Vexcel Ultracam XP</a>: the array of sensors on the focal plane cannot cover the entire field of view of the lens. So, instead, they use a rectangular array of sensors, spaced closely enough so that the gaps between their active areas are smaller than the active areas. By the way guys (Vexcel and ObjectVideo), you don't need four cameras to do this problem, it can be <a href="http://www.google.com/patents/US5264694">solved with three</a> (the patent just expired on 15-Jul-2012). You will still need to mount bare die.</li>
<li>The four cameras are pointed in exactly the same direction. Offsetting the lenses by one sensor's width reduces the required lens field of view by 2.86 degrees, to about 59 degrees. That's not much help. And, you have to deal with the <i>nominal </i>distortion between the lenses. Lining up the optical axes means the nominal distortion has no effect on alignment between sensors, which I'm sure is a relief.</li>
<li>The sensor pattern shown in the paper has 105 sensors per camera, and at one point they mention 398 total sensors. The first may be an earlier configuration and the latter is probably a typo. I think the correct number is 92 sensors per camera, 368 total. So I think the actual pattern is a 12x9 rectangular grid with 11.33mm x 8.50mm centers. 16 corner sensors (but not 4 in each corner) are missing from the 9x12=108 rectangle, to get to 92 sensors per focal plane. The smallest package that those sensors come in is 10mm x 10mm, which won't fit on the 8.5mm center-to-center spacing, so that implies they are mounting bare die to the focal plane structure.</li>
<li>They are carefully timing the rolling shutters of the sensors so that all the rolling shutters in each row are synchronized, and each row starts it's shutter right as the previous row finishes. This is important, because otherwise when the camera rotates around the optical axis they will get coverage gaps on the ground. I think there is a prior version of this camera called Gorgon Stare which didn't get this rolling shutter synchronization right, because there are <a href="http://www.redicecreations.com/article.php?id=13995">reports of "floating black triangles"</a> in the imagery, which is consistent with what you would see on the outside of the turn if all the rolling shutters were fired simultaneously while the camera was rotating. Even so, I'm disappointed that the section on electronics doesn't mention how they globally synchronize those rolling shutters, which can be an irritatingly difficult problem.</li>
<li>They are storing some of the data to laptop disk drives with 160 GB of storage. It appears they may have 32 of these drives, in which case they've got enough space to potentially store the entire video stream, but only with very lossy video compression. The design presented has only JPEG2000 (not video) compression, which will be good for stepping through the frames, but the compression ratio will be bulky enough that there is no way they are storing all the video.</li>
<li>They have 184 FPGAs at the focal plane for local sensor control, timestamping, and serialization of the data onto 3.3 Gb/s fiber optics. Supposedly the 3.3 Gb/s SerDes is on the FPGA, which sounds like a <a href="http://www.xilinx.com/support/documentation/data_sheets/ds100.pdf">Virtex-5 20T</a>. But something is odd here, because having the SerDes on the FPGA forces them to choose a fairly beefy FPGA, but then they hardly do anything with it: the document even suggests that multiplexing the two sensor data streams, as well as serialization of those streams, happens outside the FPGA (another typo?). So what's left for a Virtex-5 to do with a pair of sensors? For comparison, I paired one Spartan-3 3400A with each sensor in R7, and we were able to handle 15 fps compression as well as storage to and simultaneous retrieval from 32 GB of SLC flash, in that little FPGA. Maybe the SerDes is on some other device, and the FPGA is more of a PLD.</li>
<li>The data flows over fiber optics to a pile of 32 6U single board computers, each of which has two mezzanine cards with a Virtex 5 FPGA and two JPEG2000 compressors on it.</li>
</ul>
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Now here's my critique of this system design:</div>
<ul>
<li>They pushed a lot of complexity into the lens.</li>
<ul>
<li>It's a wide angle, telecentric lens. Telecentric means the chief rays coming out the back, heading to the focal plane, are going straight back, even at the edges of the focal plane. Said another way, when you look in the lens from the back, the bright exit pupil that you see appears to be at infinity. Bending the light around to do that requires extra elements. This looks a lot like the lenses used on the Leica ADS40/ADS80, which are also wide angle telecentric designs. The Leica design is forced into a wide angle telecentric because they want consistent colors across the focal plane, and they use dichroic filters to make their colors. The ARGUS-IS doesn't need consistent color and doesn't use dichroics... they ended up with a telecentric lens because their focal plane is flat. More on that below.</li>
<li>The focal lengths and distortions between the four lenses must be matched very, very closely. The usual specification for a lens focal length is +/- 1% of nominal. If the ARGUS-IS lens were built like that, the image registration at the edge of field would vary by +/- 500 microns. If my guesses are right, the ARGUS-IS focal plane appears to have 35x50 microns of overlap, so the focal lengths of the four lenses will have to match to within +/- 0.07%. Wow.</li>
<li>"The lenses are athermalized through the choice of glasses and barrel materials to maintain optical resolution and focus over the operational temperature range." Uh, sure. The R7 StreetView rosette has 15 5 megapixel cameras. Those lenses are athermalized over a 40 C temperature range, and it was easy as pie. We just told Zemax a few temperature points, assumed an isothermal aluminum barrel, and a small tweak to the design got us there. But those pixels have a field of view of 430 microradians, compared to the pixels behind the ARGUS-IS lens, which have a 25 microradian PFOV. MIL-STD-810G, test 520.3, specifies -40 C to 54 C as a typical operating temperature range for an aircraft equipment bay. If they had anything like this temperature range specified, I would guess that this athermalization requirement (nearly 100 degrees!) came close to sinking the project. The paper mentions environmental control within the payload, so hopefully things aren't as bad as MIL-STD-810G.</li>
<li>The lenses have to be pressure compensated somehow, because the index of refraction of air changes significantly at lower pressures. This is really hard, since glasses, being less compressible than air, don't change their refractive indices as fast as air. I have no particularly good ideas how to do it, other than to relax the other requirements so that the lens guys have a fighting chance with this one. Maybe the camera can be specified to only focus properly over a restricted range of altitudes, like 4km to 8km. (ARGUS-IR specifies 0 to 10km. It's likely ARGUS-IS is the same, so no luck there.) Or maybe everything behind their big flat window is pressurized.</li>
</ul>
<li>They made what I think is a classic system design mistake: they used FPGAs to glue together a bunch of specialized components (SerDes, JPEG compressors, single board computers), instead of simply getting the job done inside the FPGAs themselves. This stems from fear of the complexity of implementing things like compression. I've seen other folks do exactly the same thing. Oftentimes writing the interface to a off-the-shelf component, like a compressor or an encryption engine, is just as large as writing the equivalent functionality. They mention that each Virtex-5 on the SBC has two 0.6 watt JPEG2000 chips attached. It probably burns 200 mW just talking to those chips. It seems to me that Virtex could probably do JPEG2000 on 80 Mpix/s in less than 1.4 watts. Our Spartan-3 did DPCM on 90+ Mpix/s, along with a number of other things, all in less than 1 watt.</li>
<li>I think I remember reading that the original RFP for this system had the idea that it would store all the video shot while airborne, and allow the folks on the ground to peruse forward and backward in time. This is totally achievable, but not with limited power using an array of single-board PCs.</li>
</ul>
Let me explain how they ended up with a telecentric lens. A natural 85mm focal length lens would have an exit pupil 85mm from the center of the focal plane. Combine that with a flat focal plane and sensors that accept an f/1.8 beam cone (and no offset microlenses), and you get something like the following picture. The rectangle on the left is the lens, looking from the side. The left face of the right rectangle is the focal plane. The big triangle is the light cone from the exit pupil to a point at the edge of the focal plane, and the little triangle is the light cone that the sensor accepts. Note that the sensor won't accept the light from the exit pupil -- that's bad.<br />
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There are two ways to fix this problem. One way is to make the lens telecentric, which pushes the exit pupil infinitely far away from the focal plane. If you do that, the light cone from the exit pupil arrives everywhere with it's chief ray (center of the light cone) orthogonal to the focal plane. This is what ARGUS-IS and ADS-80 do.<br />
<br />
The other way is to curve the focal plane (and rename it a Petzval surface to avoid the oxymoron of a curved focal plane). Your retina is curved behind the lens in your eye, for example. Cellphone camera designers are now looking at curving their focal planes, but it's pretty hard with one piece of silicon. The focal plane array in ARGUS-IS is made of many small sensors, so it can be piecewise curved. The sensors are 7.12 mm diagonally, and the sag of a 85 mm radius sphere across 7.12 mm is 74 microns. The +/- 9 micron focus budget won't allow that, so curving the ARGUS-IS focal plane isn't going to allow a natural exit pupil. The best you can do is curve the focal plane with a radius of 360 mm, getting 3.6 mm of sag, and push the exit pupil out to about 180 mm. It's generally going to be easier to design and build a lens with an exit pupil at 2x focal length rather than telecentric, but I don't know how much easier. Anyway, the result looks like this:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqG_o5SbyLza8arJeap7_rP2Xvghp8jIu-0JE3K6ZVpkdSVdXeeDl-EEEHFbvs7qSGoCyTQOLDeEaUonqTDIQazvTeVV4gWKqGaygXmJCYIT9xM3_2lIYjpeTGu-JzG7xQcYU/s1600/extended+exit+pupil+drawing.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqG_o5SbyLza8arJeap7_rP2Xvghp8jIu-0JE3K6ZVpkdSVdXeeDl-EEEHFbvs7qSGoCyTQOLDeEaUonqTDIQazvTeVV4gWKqGaygXmJCYIT9xM3_2lIYjpeTGu-JzG7xQcYU/s400/extended+exit+pupil+drawing.png" width="400" /></a></div>
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As I said, the ARGUS-IS designers didn't bother with this, but instead left the focal plane flat and pushed the exit pupil to infinity. It's a solution, but it's not the one I would have chosen.</div>
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Here's what I would have done to respond to the original RFP at the time. Note that I've given this about two hours' thought, so I might be off a bit:<br />
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<li>I'd have the lenses and sensors sitting inside an airtight can with a thermoelectric cooler to a heat sink with a variable speed fan, and I'd use that control to hold the can interior to between 30 and 40 C (toward the top of the temperature range), or maybe even tighter. I might put a heater on the inside of the window with a thermostat to keep the inside surface isothermal to the lens. I know, you're thinking that a thermoelectric cooler is horribly inefficient, but they pump 3 watts for every watt consumed when you are pumping heat across a level. The reason for the thermoelectric heat pump isn't to get the sensor cold, it's to get tight control. The sensors burn about 600 mW each, so I'm pumping 250 watts outs with maybe 100 watts.</li>
<li>I'd use a few more sensors and get the sensor overlap up to 0.25mm, which means +/-0.5% focal length is acceptable. I designed R5 and R7 with too little overlap between sensors and regretted it when we went to volume production. (See Jason, you were right, I was wrong, and I've learned.)</li>
<li>Focal plane is 9 x 13 sensors on 10.9 x 8.1 mm centers. Total diameter: 105mm. This adds 32 sensors, so we're up to an even 400 sensors.</li>
<li>Exiting the back of the fine gimbal would be something like 100 flex circuits carrying the signals from the sensors.</li>
<li>Hook up each sensor to a Spartan-3A 3400. Nowadays I'd use an Aptina AR0330 connected to a Spartan-6, but back then the MT9P001 and Spartan-3A was a good choice.</li>
<li>I'd have each FPGA connected directly to 32GB of SLC flash in 8 TSOPs, and a 32-bit LPDDR DRAM, just like we did in R7. That's 5 bytes per pixel of memory bandwidth, which is plenty for video compression.</li>
<li>I'd connect a bunch of those FPGAs, let's say 8, to another FPGA which connects to gigabit ethernet, all on one board, just like we did in R7. This is a low power way to get connectivity to everything. I'd need 12 of those boards per focal plane. This all goes in the gimbal. The 48 boards, and their power and timing control are mounted to the coarse gimbal, and the lenses and sensors are mounted to the fine gimbal.</li>
<li>Since this is a military project, and goes on a helicopter, I would invoke my fear of connectors and vibration, and I'd have all 9 FPGAs, plus the 8 sensors, mounted on a single rigid/flex circuit. One end goes on the focal plane inside the fine gimbal and the other goes on the coarse gimbal, and in between it's flexible.</li>
<li>I'd connect all 52 boards together with a backplane that included a gigabit ethernet switch. No cables -- all the gigE runs are on 50 ohm differential pairs on the board. I'd run a single shielded CAT-6 to the chopper's avionics bay. No fiber optics. They're really neat, but power hungry. Maybe you are thinking that I'll never get 274 megabits/second for the Common Data Link through that single gigE. My experience is otherwise: FPGAs will happily run a gigE with minimum interpacket gap forever, without a hiccup. Cheap gigE switches can switch fine at full rate but have problems when they fill their buffers. These problems are fixed by having the FPGAs round-robin arbitrate between themselves with signals across that backplane. Voila, no bandwidth problem.</li>
<li>The local FPGA does real time video compression directly into the flash. The transmission compression target isn't all that incredible: 1 bit per pixel for video. That gets 63 channels of 640x400x15 frames/sec into 274 Mb/s. The flash should give 1 hour of storage at that rate. If we want 10 hours of storage, that's 0.1 bits/pixel, which will require more serious video compression. I think it's still doable in that FPGA, but it will be challenging. In a modern Spartan-6 this is duck soup.</li>
<li>The computer tells the local FPGAs how to configure the sensors, and what bits of video to retrieve. The FPGAs send the data to the computer, which gathers it up for the common data link and hands it off.</li>
<li>I'll make a guess of 2 watts per sensor+FPGA+flash, or 736 watts. Add the central computer and switch and we're at 1 kilowatt. Making the FPGAs work hard with 0.1 bit/pixel video compression might add another 400 watts, at most.</li>
<li>No SSDs, no RAID, no JPEG compression chips, no multiplexors, no fiber optic drivers, no high speed SerDes, no arrays of multicore X86 CPUs. That's easily half the electronics complexity, gone.</li>
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UPDATE 25-Jan-2013: Nova ran a program on 23-Jan-2013 (<a href="http://www.pbs.org/wgbh/nova/military/rise-of-the-drones.html">Rise of the Drones</a>) which talks about ARGUS-IS. They present Yiannis Antoniades of BAE systems as the inventor, which suggests I have the relationship between BAE and ObjectVideo wrong in my description above. They also say something stupid about a million terabytes of data per mission, which is BS: if the camera runs for 16 hours the 368 sensors generate 2,000 terabytes of raw data.<br />
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They also say that the ARGUS-IS stores the entire flight's worth of data. I don't think they're doing that at 12 hertz, certainly not on 160 GB drives. They've got 32 laptop drives in the system (one per single board computer). If those store 300 GB apiece, that's 10 terabytes of total storage. 16 hours of storage would require 0.05 bits/pixel -- no way without actual video compression. The JPEG2000 compressor chips are more likely to deliver at best 0.2 bits/pixel, which means they might be storing one of every four frames.<br />
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UPDATE 27-Jan-2013: An alert reader (thanks mgc!) sent in this article from the April/May 2011 edition of Science and Technology Review, which is the Lawrence Livermore National Laboratory's own magazine. It has a bunch of helpful hints, including this non-color-balanced picture from ARGUS-IS which lets you see the 368 sensor array that they ended up with. It is indeed a 24 x 18 array with 16 sensors missing from each corner, just as I had hypothesized.<br />
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<a href="https://str.llnl.gov/AprMay11/images/per4.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="302" src="https://str.llnl.gov/AprMay11/images/per4.jpg" width="320" /></a></div>
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The article mentions something else as well: the Persistics software appears to do some kind of super-resolution by combining information from multiple video frames of the same nearly static scene. They didn't mention the other two big benefits of such a scheme: dynamic range improvement and noise reduction (hence better compression). With software like this, the system can benefit from increasing the focal plane to 3.8 gigapixels by using the new sensor with 1.66 micron pixels. As I said above, if the lens is f/3.5 to f/4.0 lens they won't get any more spatial frequency information out of it with the smaller pixels, but they will pick up phase information. Combine that with some smart super-resolution software and they ought to be able to find smaller details. Question though: why not just go to the MT9F002, which gives you 14 million 1.4 micron pixels? This is a really nice, fast sensor -- I've used it myself.</div>
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The article also mentions 1000:1 video compression. That's very good: for comparison, H.264 level 4 compresses 60 megapixels/second of HDTV into 20 megabits/second, which is 0.33 bits/pixel or 36:1 compression. This isn't a great comparison, though, because Persistics runs on almost completely static content and H.264 has to deal with action movie sequences. In any case, I think the Persistics compression is being used to archive ARGUS-IS flight data. I don't think they are using this compression in the aircraft.</div>
Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com1tag:blogger.com,1999:blog-8628325.post-58348807626375613532012-08-13T11:53:00.001-07:002012-08-13T11:53:40.252-07:00More vision at 360nmI thought of two other consequences of birds, especially hawks, seeing ultraviolet light.<div>
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The first has to due with scattered light. The nitrogen and oxygen molecules in the atmosphere act like little dipoles, scattering some of the light passing through. The amount of light scattered increases as the fourth power of frequency (or inverse fourth power of wavelength). The process is called <a href="http://en.wikipedia.org/wiki/Rayleigh_scattering">Rayleigh scattering</a> (yep, same guy as the last rule).<div>
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Because of that strong wavelength dependence, our blue-sensitive cones receive 3 times as much light scattered by nitrogen and oxygen as our red cones, and when we look up at a cloudless sky in the day, we see the sky is blue. Here are the response curves for the three types of cones and the rods in human vision. (That's right, you actually have <i>four </i>color vision, but you can only see blue-green (498nm) with your rods when it's too dim for your cones to see.)</div>
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But now imagine what a hawk sees. It has another color channel at 360nm, which sees 6 times as much scattered light as red. When looking up, the sky will appear more UV than blue. But there is more to it than that.</div>
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Rayleigh scattering is not isotropic. The dipoles scatter most strongly at right angles to the incoming light. When you look up at the sky, the intensity of blue changes from near the sun to 90 degrees away. It's a little hard to see because when looking up you also see Mie scattering which adds yellow light to the visible sky near the sun. But when you look down, like a hawk does, Mie scattering isn't an issue (instead you have less air Rayleigh scattering and more ground signal). The overall color gradient from Rayleigh scattering that a hawk sees looking down will be twice as strong as the color gradient we see, because the hawk sees in UV. In direct sunlight, the hawk has a measure of the sun's position whenever it is looking at the ground, even when there are no shadows to read.</div>
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The other consequence is axial chromatic aberration. Most materials have dispersion, that is, they present a different index of refraction to different wavelengths of light. One consequence of dispersion is that blue focusses in front of red (for lenses like the eye). I used to think this was a bad thing. But if your cones tend to absorb light of one color and pass light of the others, and your resolution is limited by the density of cones, a little chromatic aberration is a good thing, because it allows you to stack the UV cones in front of the blue cones in front of the green and red cones, and they all get light focussed from the same range. I know that retinas have layered stacks of rods, cones, and ganglion cells, but I don't know that any animals, hawks in particular, have actually taken advantage of axial chromatic aberration to stack cones of different colors. It's certainly something I'll be looking for now.</div>
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Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0tag:blogger.com,1999:blog-8628325.post-2556517910616352962012-08-12T14:34:00.003-07:002012-08-12T14:34:31.362-07:00Hawk eyed<div class="separator" style="clear: both; text-align: center;">
<a href="http://upload.wikimedia.org/wikipedia/commons/3/3e/Hawk_eye.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="317" src="http://upload.wikimedia.org/wikipedia/commons/3/3e/Hawk_eye.jpg" width="320" /></a></div>
<br /><br />The resolution of a good long-distance camera is limited by diffraction. The simple rule for this is the <a href="http://en.wikipedia.org/wiki/Rayleigh_criterion">Rayleigh criterion</a>:<br /><img src="http://upload.wikimedia.org/wikipedia/en/math/f/d/8/fd83540e22140c050d0de6c139415bf1.png" /> <br /> Theta is the angular resolution, the smallest angular separation between two bright lines that can be differentiated by the system.<div>
<br />Lambda is the wavelength of light. You can see reds down at 700nm, and blues to 400nm. Interestingly, <a href="http://people.eku.edu/ritchisong/birdbrain2.html">birds can see ultraviolet light at 360nm</a>. The usual explanation for this is that some flowers have features only visible in ultraviolet, but I think raptors are using ultraviolet to improve their visual acuity.<br /><br />D is the diameter of the pupil. Bigger pupils not only gather more light, but they also improve the diffraction limit of the optical system. The trouble with bigger pupils is that they make various optical aberrations, like spherical aberration, worse. These aberrations are typically minimized near the center of the optical axis and get much worse farther from the optical axis. So a big pupil is good if you want a high-resolution fovea and are willing to settle for crummy resolution but good light gathering outside that fovea. This is the tradeoff the human eye makes.<br /><br />A human's eye has a pupil about 4mm across in bright light. According the Rayleigh criterion, human resolution at 550nm should be about 170 microradians. According to <a href="http://en.wikipedia.org/wiki/Eye">a Wikipedia article on the eye</a>, humans can see up to 60 counts per degree, which corresponds to 290 microradians per line pair. That suggests the human eye is not diffraction limited, but rather limited by something else, such as a combination of focal length and the density of cone cells on the retina.<br /><br />I wasn't able to find a good reference for the pupil diameter of a red-tailed hawk. Judging from various pictures, I'm guessing it could be smaller than a human pupil, since it appears that the hawk's eyeball is quite a bit smaller than the human eye (absolute scale). This doesn't seem good enough, since hawks are reputed to have fabulous vision. The first reference I found online suggested that hawks have visual acuity that's <a href="http://altamontsrc.org/alt_doc/raptor_acuity_and_wind_turbine_blade_conspicuity_mcissac.pdf">actually worse</a> than humans.<br /><br />Suppose that this last study was using paints that were undifferentiated in UV, in particular, around 360 nm. The researchers would not have noticed this. Suppose further that hawks are using 360 nm light for high acuity vision. The diffraction limit of a 4 mm aperture in 360 nm light is 110 microradians. This isn't 8 times better than human vision, but it is sufficient to distinguish two twigs 1 cm apart from 100 meters up.<div>
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</div>Ambivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.com0