Gravity Assist Competition

Or The Space Game, by ESA.

Minimize delta vee by moving the planets around (this changes the probe's arrival time at the planet). This shows my best solution so far, with some playing one evening, about 13 km/s

This is a nice javascript webpage where a probe is shot from Earth to Jupiter with gravity assists at Venus (twice), Earth and Mars. You try to achieve the lowest propulsive delta vee. You decide when the spacecraft arrives at each encounter and the program basically calculates the rest. It’s quite a nifty little piece of Javascript, the future of web applications is like this. It works fine with Chrome on Linux at least. Probably IE will have problems but who uses that anyway?

I’m ranked at #39 at 12.74 km/s… Far behind the gurus who get below 10 km/s readings! There are apparently some prizes for the top three, but I think people are in it for the fun of it.

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Humans Fast, Machines Slow

Rand Simberg talks about impedance matching. So I’d like to make a post of my comment there (I’ve always wondered why this obvious alternative gets mentioned so little…)

What to do when you arrive at Mars or Earth with your solar electric propelled vessel?

So, the problem with most low fuel demand velocity change schemes is that they only give slow accelerations. Low fuel high velocity change means solar or nuclear electric propulsion and aerocapture mainly.

High delta vee aerobraking is hard to do in one pass – it gets dangerous because of atmospheric variability and potentially other reasons.

Simple: detach a small capsule with the humans that goes directly to the surface (with only days of life support) and leave the untended craft to do multi-pass aerobraking. Hitting van Allen belts a few more times or taking a long time doesn’t matter that much with no humans onboard.

You could also potentially ultimately leave the long distance craft at some Lagrange point instead of LEO. (Cue some clever and complex maneuvers to save fuel – maneuvers that take long.)

Something similar could also be done when a long distance stack is assembled in LEO: send the humans there only after it’s through the belts. They can go with a smallish capsule again. Potentially at some Lagrange point, or in space without any fixed reference, just along the way. It could be dangerous though if the capsule doesn’t have much life support.

Many of these things have potential delta vee penalties as well as timing inflexibilities, but they could have enough other benefits that they should be considered.

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All Tarkovski Films Free Online

Noticed by Things Break. I’ve only seen Solaris. It had a lot of good in it, although it was quite uneven and somewhat overlong. Certain acting is very intensive and memorable. Having read the book twice, I even experienced it completely differently both times. The American version from 2002 with George Clooney I haven’t seen completely, but from the first quarter, it seems to have some large stylistic jumps from the book which I find odd – the props in the seventies Soviet version actually seemed much more fitting to me! Probably everybody just reads the book differently.

One of the great themes of Stanislaw Lem seems to be dysfunctional organizations. This should ring a bell with my readers… 😉 Though Solaris is very different from all of his other stories. But I don’t want to spoil too much.

I have also read the Strugatski brothers’ Stalker, which was also cinematized by Tarkovski. It was a peculiar book and felt somehow like a weird mishmash with too much familiar and unreal blended to work as a whole. With some changes it might actually work well with modern special effects – or I hear that the computer game of the same name actually is great, though maybe not very plot intensive. Stalker was actually filmed in Tallinn, Estonia I hear and you can see the place somewhere there (if they haven’t torn it down, they’re rebuilding at a pace there).

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The Last I4

It doesn’t have the same sound as “The Last V-8” now does it? When you look at what’s happening in the world of automobiles, you get some idea of a change. It is always slow, yet I predict that when it happens, probably starting before the end of this year, people are taken by surprise.

Why Would Anyone Buy A Hybrid Car?

It doesn’t have that much better fuel economy than a modern petrol or diesel engine if you drive out of the city, and it costs some more and is complicated. New turbocharged and variable valve engines can do pretty well because they can be built to opearate in a flexible manner. BMW has even introduced a technique that could be called a “virtual hybrid” – where the aircon compressor and battery charger are disconnected when the gas pedal is pushed to the bottom, resulting in extra power available for traction – allowing a smaller engine to achieve the same acceleration.

In some cases, like buses that need to stop often, hybrids make great sense, but otherwise I see the improvements in ordinary direct internal combustion engine driven cars narrowing the gap quite considerably. On the highway the hybrid has no advantage.

A Seemingly Small Addition

Volvo V70 Plugin Hybrid Prototype

So, add a grid recharge capability and you have a plugin hybrid. By itself that’s not much yet though, you have to enlarge the batteries too. Since most trips for most people are commuting and errands, they’re short and can be done entirely on battery power. You also still haul the gasoline engine along and it is used on longer trips. Most problems solved right here? Sounds easy.

Chevy Volt / Opel Ampera is coming soon. And just take a look at the huge number of plugin hybrids being developed, listed at Plugin America. Most of these will be dead ends, but some might make it big.

Pure Electric Cars – The Charging Problem

The problem is, gasoline is very very energy intensive. If a car uses 8 L for 100 km and a 10 kWh worth of energy, then tankage of 40 liters gives about 50 kWh of energy. Done in 50 seconds this stream of gasoline through the hose is worth 1 kWh per second or 3.6 megawatts. High enough temperature superconductors have not yet been invented that would make a hand-attachable 3.6 megawatt car charger possible. If we generously assume 240 Volts and 40 Amperes, the charging power is only 10 kilowatts. The largest home appliances like sauna stoves and water heaters are in the single kilowatts range. They often use 380 V three phase power here, but that gets slightly impractical for a car charger. This thousandfold disparity in energy replenishment speed is striking. An optimistic 10 kW charger would charge a 100 km drive’s worth of energy in an hour. Certainly useful for commuters. Charging as range extension seems doubtful. Our summer cottage is 300 km from Helsinki. If a full battery only lasts the first 200 km, one would have to stop at a loading station for one hour before one could drive the rest of the way. Not realistic. The penalty of lugging around the heavy and complicated IC engine has to be bitten at this point of battery development.

Battery Improvements?

There exist some pretty high energy per mass battery technologies right now, but they are expensive and use rare materials like cobalt that they can never really be mainstream solutions on something that stores energy in the megawatt hour class. Hopefully with enough money now available, some cheaper and less material intensive ways to store electrical energy can be developed.

Your Local Correspondent

Naturally, Finland would be a pretty ideal place to have electric and plugin hybrid vehicles. A significant portion of the populace keeps their cars parked in a spot with an electric socket nearby – those house timers that turn on the cylinder block heater on an hour or so before leaving for work in the wintertime, meaning less fuel use and wear for the engine. It is trivial to use those 240 V outlets for electric car charging. Also, electric cars are actually manufactured in the city of Uusikaupunki, Finland by Valmet. The Th!nk City is one. Too bad because of insane tax policies, it is not actually sold here – at the moment you can only get them in Norway, Austria and Holland. The Fisker Karma electric sports car will also be manufactured in “Uki”. I think they have a long nose on the car for Freudian reasons – since it doesn’t need to hold a long block internal combustion engine – or maybe it’s just that buyers are conservative. And then there’s the e-cars now project aiming to refit old Toyota Corollas with electric motors and batteries. But there’s more.

Automotive X-Prize

There’s that going on, which is actually interesting! My favorite vehicle is the Peraves E-Tracer.

Here are the results from August 2 but I still don’t know what will change / what is coming because the pages are unclear: [EDIT: fresh info at the blog indicates some testing is still going on]

1st Place Team Lithium Ion Motors of North Carolina (125 MPGe average fuel economy for the event)
2nd Place RaceAbout Association of Finland (0.179 seconds behind the leader and 100 MPGe average fuel economy for the event)
3rd Place TW4XP of Germany (11 minutes, 36.9 seconds behind the leader and 139 MPGe average fuel economy for the event)
4th Place ZAP of California (DNF – 48 laps completed)
5th Place Aptera of California (DNF – 18 laps completed)

The Raceabout team is from Helsinki’s Metropolia university of applied sciences. They have a long background of building electric vehicles, and it’s nice to see something in the competition that looks like an actual car, yet still manages to do so well.

RaceAbout's E-RA vehicle in the Automotive X-Prize 2010 competition

Hopefully the politicians here can get something sensible done, and the super-high taxes on electric vehicles (basically, anything that isn’t gasoline or diesel is considered fishy and is taxed hugely) can be dropped so we can start seeing more of them here! The current situation is a travesty!

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The Laws of Physics

Regarding light gathering area and sensor noise are harsh. Well, it was cheap and it’s tiny and has a rechargeable battery. Maybe it’ll do something worthwhile. The view is from the kitchen window after 11 pm. Why do these things have 10 megapixels? I took the pic in 3 MP mode,  scaled it down in Gimp to about one and it’s still too big, most of the information is just noise. Better use that smallest picture mode so I can use that SD card for a loong time… I also edited the curves slightly to bring more forest and less white in the sky. OK, maybe I’m being a bit rough on it, that’s a huge contrast between the sky and the trees.

Nine Megapixels Noise, One Signal

Nikon Coolpix S203 it is by the way, though these are all probably made in the same factory… 😉

If someone brought to market a 3 mpix camera with twice the quantum well depth, that’d be interesting.

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Betting on 400 PPM CO2

Well, not real money. But Atmoz is discussing about when it will be reached with commenters. My bet is march 2018, though if you use woodfortrees to visualize, straight extrapolation seems to predict before 2015 already, for the northern hemisphere winter peak. Most seem to bet around 2014-2016.

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BP Phones Child Psychiatrist

How does a corporation respond to a disaster it has created? By seeking the best PR strategy by polling around which response might look like the best move! Is this for real? Thanks to Things Break.

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Avatar

Finally saw it. Some friends gave me a free ticket that had a few days to expiration since they couldn’t use it. The text below contains spoilers.

The Story

Well, Pocahontas has been brandied about. And it was somewhat like what I expected it to be. But most of all, I was reminded of the real case of rebels in Papua New Guinea. Some copper was found on some original peoples’ land, a mine was built that polluted the environment, they started fighting it with really primitive weapons. The miners brought some Australian hired guns to kill them but it was exposed by the Australian press and they withdrew from the project. The rebels managed to seize the area, and the mine was shut down. Government troops couldn’t go to that part of the country anymore. They had gotten some better weapons at some point too. They had also seemed to self-organize otherwise. Drove old beat up pickup cars with self refined palm oil, had self built hydro power plants in the hills etc etc.. In such a warm and relatively easy environment you don’t need that much organization to improve your quality of life some. I saw all this in a documentary some five years ago.

So even when Avatar seemed very cheesy at many times, it still had some interesting connections to reality. Sometimes reality is cheesy like that.

I can imagine general criticism against the plot. Slashdot headlined how “anti-technology” it seemed. There is no examination of the native culture, it’s just some cliche of being one with the nature and running around in freedom. Can they cure sicknesses or survive if the weather turns bad? Could they actually get a lot from a more modern civilization? Certainly in real life many natives have left their materially poor tribes to pursue a more affluent life in the western culture. An inuit sitting in an oil company office commented how bad a seal really tastes – that he’d take a bic mac over it any day.

But is this all how relevant? That is not at the core of the story. The basic idea was that the Na’vi tribe was sitting on something valuable, a big chunk of unobtainium. No matter how happy and successful the blueskins would have been in their way of life, they could be labeled as enemies, like the protagonist Jake Sully comments to Parker Selfridge, the company man leading the mining operation.

On one hand, it would be interesting to see the mental gymnastics excercised to prove that of course the company had the right to drive off the natives from their home and take the mineral, and I’m sure the internet is full of such stuff. It naturally bears some resemblance to the Iraq case (though that is not so simple), and a large portion of people in the English speaking world have so much emotionally invested in it that it’s hard to discuss in any interesting way.

It might also have effected my experience that I had just read a short interview of Ilmari Juutilainen, a Finnish ace who shot down some ninety Soviet planes in the second world war. He naturally felt that fighting for your independence and not yielding to a bigger nation’s demands was a very important thing. He had survived situations that seemed completely impossible and I recommend the interview to everyone. So, as a Finn, I naturally identified strongly with the natives in the film. We just wanted to be left alone and live our own life which we were perfectly capable of doing. Naturally the Soviet Union invented some reasons to attack us, even shelling their own border village, Mainila. So, a single movie is too short for including much, but the whole propaganda machine and willing press would have made a great part for it too; how it would have portrayed the savages’ “brutal and unprovoked attacks” to the public back on Earth, and created a will to murder the blueskins.

War is not simple, nor is peace, but one can not withdraw from moral judgments.

The Technology

Well, the 3D was worse than I expected. It didn’t work seamlessly for me, I saw things kind of partly double a large portion of the time. Also the picture seemed quite jerky. Fast action is bad in movies anyway (Transformers was awful for the most part!) but this was even worse with the closeups of folks running in jungle just turning into a total mess. Luckily Cameron or his photographer had the sensibility to pull in some wider and also slower shots at times. It’s perhaps old-fashioned nowadays but those were the best part of the movie.

Polarization

So, you’re probably reading this on an LCD. All light is first polarized in one direction, then it passes through tiny liquid crystals that can twist the polarization if they are twisted with an electrical field, or then they keep it straight. Then there is a final filter panel with yet a polarization. If the liquid crystal twists the incoming light so that it is in a different polarization than the outgoing filter, then that pixel is black. If it’s the same way, the pixel is full brightness.

In a 3D viewing technology, the idea is to give different eyes different images so the brain reconstructs the 3D image from that.

Now, just change the original initial and filter polarizers of half of your pixels, and there you have it. Your LCD was already that close to being a 3D display!

Say, now half of the pixels have vertical and half have horizontal polarization. You of course need to also change the software so that half the pixels work with reverse logic from the old way, but that’s very easy. Then, wear specs with a vertical polarization surface on one eye and a horizontal polarization surface on the other and the eyes can see different pictures. One eye sees the odd and one the even pixels. The rest is just software. Of course, brightness and resolution suffers as both see just half the pixels, but things like frame rate and everything else stay just identical. No flickering or any other problems like that persist, like with glasses or projectors that do some switching. Movement should be exactly as smooth as with no 3D. The glasses can also be perfectly passive with no need for batteries. And cheap, so you can get as many as you want.

Now, projectors use LCD:s as well. You just have to have a screen that keeps the polarization.

I don’t know why this kind of 3D technology is not used more widely. It seems totally trivial to implement with just small changes to a factory built ordinary LCD display.

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Hydrogen Polymers – A Game Changing Invention

Always keeping up to date on materials technology, I’ve closely followed the buzz how a few research groups around the world have been working on a super-material that’s so many things at once.

If you think about it, carbon is great – it’s atomic mass is only 12 but it can form strong bonds and chain up to form polymers, like the many fibers or even nanotubes. Far better than iron or aluminium, that are such huge drags at weights of 56 and 27 respectively.

But what about even lighter materials? Hydrogen has a single proton for an atomic mass of 1, yet it has a freely moving electron that can do wonders.

Hydrogen polymers work by aligning the spins of the electrons so that the magnetic fields align and reinforce each other. Think like a bunch of magnets stacked north-south-north-south-etc. This both increases the density of hydrogen and creates strong hydrogen polymer chains. That makes it doubly useful – both as a material and as a way to store hydrogen.

So, you can say bye-bye to the heavy batteries made of precious and ever rarer metals – the hydrogen age is here after all!

It’s one of those things that seem so obvious in hindsight and could probably have been done decades ago already.

Think about a material as strong as carbon fiber, but one twelvth the mass!

Instant personal helicopters for everyone. Powered by the same hydrogen polymers as well, no less!

It can’t yet take very high temperatures, but room temperature has already been demonstrated in a lab at the University of Essen.

[EDIT:  so this was an April fool’s joke I came up with quickly some hours after midnight when the day turned to April 1. More information at Wikipedia on molecular orbitals.]

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The Martin Jetpack and Its Design Tradeoffs



Here’s the technical information. It uses a piston engine to spin two smallish propellers. At first look it seems inefficient: the propellers are so small (diameter 1.7 ft so radius is 0.26 m) so the air mass flow is low and hence the velocity of the jet must be high, meaning high power needs for the thrust. (Mind you, it’s efficient compared to a peroxide rocket or a low bypass turbofan engine that have been used for jetpacks in the past.)

But let’s look closer. Engine specs. It’s a two stroke 2.0 liter V4 that produces about 150 HP at 6000 RPM and it weighs 60 kg. The quite high RPM means it produces quite high power.

If the engine spun at a lower speed, you could use bigger props, but the engine would produce less power.

If it spun at a higher speed, you could have higher power for little mass growth in the engine and then use a gearbox to still use the same size or even bigger props (if you geared it down further). But gearboxes are heavy, expensive and often unreliable.

6000 rpm is 100 Hz (rpm is a totally weird unit for spin rate anyway, why is it always used?). Speed of sound is 320 m/s. Hence at 100 Hz the supersonic radius would be 0.5 meters (100 1/s * 2 * 3.14 * 0.5 m  = 307 m/s). At the Martin Jetpack’s 0.25 m blade radius it’s about half the speed of sound. At the 7058 max RPM it’s 180 m/s or about 60% of Mach 1 – the transonic region should be easily avoided. Maybe they could be even slightly bigger.

It’s a compromise design. With the small props you can use relatively high engine speeds so your engine stays light – and you avoid a complex expensive failure-prone gearbox. The machine also stays safe as there is no free flailing propeller. With a larger propeller (or two) you would have to give up the shroud(s) since their weight would be prohibitive. On the other hand, fuel consumption would go down and hence the range could increase. It’s a fascinating design space.

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