Dirigibles require huge volumes, because the lifting power of gas is small. Those huge volumes make for a relatively weak, slow, and difficult-to-maneuver craft. A big reason why airships disappeared in favor of airplanes was that airships had a really tough time handling or avoiding bad weather because of these limitations.
I have a blurry recollection of seeing an aircraft design that was a combination of an airplane and a dirigible. It looked like a poofy manta ray, an inflated rigid lifting body or flying wing. It wasn't quite VTOL & needed a very short runway, but it also gained more maneuverability in flight. Maybe it was too much of a compromise though.
There's actually been more than one of these types of aircraft (known as Lighter Than Air - or LTA Aircraft), either as an idea or prototype throughout history.
Hydrogen doesn't buy you that much additional lifting power.
Air is about 1.2kg/m^3 at STP, so that's the theoretical maximum you can lift with a cubic meter of gas bag. (And you can only get that value if you could somehow hold a vacuum, of course.)
Hydrogen is about 0.09kg/m^3 at STP, so you can lift about 1.1kg/m^3. Helium is about 0.18kg/m^3, so you can lift about 1kg/m^3. Helium is twice as dense, but that only costs you about 10% of your lifting power since both are so light compared to air.
I see no reason you couldn't use hydrogen, but I don't know if anyone would want to take the risk. (Specific flaws of the Hindenburg aside, hydrogen is explosive across a distressingly wide range of mixture ratios with air.) If you did use hydrogen, I think the main motivation would be avoiding the use of scarce helium, not the minor increase in lift capacity.
But still critical enough to make it impractical. How would you do maintenance on a hydrogen airship without risking the people doing the maintenance? And you'd never be able to fly over populated areas.
Seems reasonable. All else being equal, your radar cross section is proportional to your actual cross section. Plus it's probably easy to spot a blimp with your eyes.
weather balloons are typically not up for that long, 90 or so minutes on average. So I don't think that's solving the extended air time. In fact they are pretty much designed to go up and pop and come back down. Lighter than air in general can be used to solve extended air time, and we're back to dirigibles, not weather balloons.
The Stanford Student Space Initiative's valbal is an interesting project where they add a lightweight set of ballast and a valve to a weather balloon so it can maintain an altitude. They're limited by power, the amount of ballast, and how much gas they can bleed but they can get flight times of days. https://stanfordssi.org/blog/ssi-52-breaks-world-record-agai...
Well, I'm disappointed that the majority of their flights are this short. I thought there were some of them which were permanent atmospheric weather stations.
But short flight times don't really have to be the case, because it seems that they can fly for extended periods of time: one of NASA's balloons stayed up for 46 days [0]. The US air force also uses balloons as surveillance stations, though I don't know the actual flight time of these [1][2]. JLENS was supposed to stay up for 30 days at a time.
sure but these aren't really weather balloons. the last two are basically tethered dirigibles. the first one is the closest and it's more like what project loon is doing. Yes, it's true, balloons can stay up for long periods of time, but this is not how weather balloons are made or what they are designed for. Weather balloons are designed to pop at a specific pressure and fall. As the balloon rises, the volume of gas expands due to there being less atmospheric pressure. At a point the balloon pops and it falls back to earth. The loon and the balloon in your first link probably use a system that adjusts the pressure in the balloon by compressing it into a storage container. This allows it to "hold" an altitude and keep the balloon from ascending until it bursts. Also, at least in loon's case, it uses a different material than a standard weather balloon. This probably also plays a roll in it's expandability, resistance to long term UV and keeping itself from popping.
Helium is rare and expensive and becoming even more so as time goes on.
Hydrogen has this nasty habit of being extremely flammable.
Rigid or semi-rigid airships when scaled up are really difficult to moor and arrange ground handling for, which is why some of the recent prototypes that have been flown integrate skirts and reverse-hovercraft like suction apparatus that can hold them down on a flat field.
The empire state building was originally intended as a Zeppelin mooring location, but the plan was abandoned due to wind and inability to control a zeppelin to that level of precision.
I wondered why this wasn't applied to suitcases to make them lighter and then common sense kicked in regarding just how much actual helium would be required to lift even an empty suitcase...
It's not even an issue of how much helium is needed; no amount of helium will make a typical suitcase buoyant.
Filling it with helium at ambient pressure wouldn't produce nearly enough lift, and increasing the pressure would make it heavier, not lighter. What's needed is not mass, but volume.
I feel like you're being deliberately obtuse. I think jianshen meant how big of a helium balloon you'd need, not how much helium you'd have to put inside the suit case.
The article said that the lighter than air aircraft got blown around by the wind too much. They needed a drone that could loiter over a specific area for an extended period of time, presumably acting as a communication relay for disaster or war zones.
I thought of that the other day, wondering how well you could possibly control a hot air balloon (or helium) based drone. My guess is wind forces etc would be extremely difficult to deal with
With a (very) good weather model, it's possible to change altitude to pick up winds going roughly where you want to go. I don't know if anything does this autonomously - Google's Project Loon is the obvious candidate.
Lol, look up google's project Loon. They are trying to give everybody internet with balooons that stay in the air a long time. They steer by going up or down into different wind currents at different altitudes
Your balloon would have to be about twice as large to compensate for the higher density of methane (.656, according to google)
I also am not sure that would be much safer than using hydrogen. Methane ignites a bit harder and would initially burn a lot slower (hydrogen has a much higher upper explosive limit (https://en.wikipedia.org/wiki/Flammability_limit), so it would need to disperse more for the gas at the center of the balloon to ignite), but _any_ fire near the surface of the balloon eventually would be catastrophic, and putting fire extinguishers everywhere isn't an option because of their weight, in combination with the huge area of your balloon)
Heat the air with direct solar to give it lift. Make it clear on the outside and have something black on the inside to absorb more heat. For bonus points, let it be deployable during flight...fly drone into position in plane mode, pop the blimp, inflating it with air from the forward travel inertia, heat it once with a small rocket motor or something, then let the sun keep it hot enough to float. When done, eject the balloon and fly back. I'm sure there are lots of details around why they don't do this.
There used to be (maybe still is?) a toy, sold by Edmund Scientific and others - that was basically a thin black and big dry cleaning bag. You'd basically take it outside on a sunny day, whip it around a bit to "fill" it with some air, tie it closed, and then let it heat up in the sun. Eventually, it would take shape, becoming buoyant, at which point you could let it go to float off (presumably tied down with a string if you wanted to keep it).
I don't know if it is still available or not, or whether anyone ever added remote controls to it...
Hmm - apparently it or something similar is still available - or you can try to build one yourself:
Think about how much weight a party balloon with helium can support. Not a lot. It could definitely not carry a camera, for example.
Hot air balloons adjust altitude by heating the helium inside the balloon and letting it cool back down as appropriate. You would need a similar mechanism, but in much smaller format.
hot air balloons use hot air (which is less dense than cool air) not helium.
they are open by design, unlike dirigibles. hot air balloons increase altitude by adding more hot air via a burner, and decrease altitude by letting the air diffuse out through holes in the top of the balloon.
> Just goes to show there's nothing remotely like organic molecules for energy density.
GTFY (generalized that for you). ;)
It's all about the energy in that carbon-hydrogen bond. Lipids have a similar energy density, which is why migrating birds have a similar nonstop range as fossil fueled airplanes (11,000 km vs 14,000 km for the 747 long range variant).
Lithium Ion battery: Ranges from 100 to 243 Wh/kilogram.
Even when you consider that something like 50% of the energy in gasoline is lost to waste heat in a typical internal combustion engine, it's still a huge difference.
It will require a tank of 4x the volume for the same energy which comes with many additional challenges. Plus, a tank that can withstand 700 bar will have to be extremely strong and heavy which hurts your energy/mass ratio.
The problem is that you need a big heavy tank to keep all of the Hydrogen molecules from escaping, especially if you're keeping it under pressure. Hydrogen is much more problematic to work with.
Nuclear is! The problem is that the minimal feasible size of the whole system is too big for an airplane. Nuclear airplanes were actively designed in 1950s, but proved to be excessively heavy and unsafe.
The thing is, even if you got the system small enough (lightbulb reactor or otherwise), you'd have one hell of a time with cooling. It works with rockets because they need to dump massive amounts of heat into propellant and generate a lot more thrust with it but airplanes fly slower and generate force through lift. If the money were there though, using something like the lightbulb for synthetic jet fuel could massively change their environmental impact.
The nuclear lightbulb is new to me, thanks for the link.
Has anybody thought through the engineering of those silica reaction vessels (I haven't searched)? I don't think it can work.
If I understand the concept shown in the Wikipedia page, it depends on uranium hexafluoride operating at 25,000°C in fused silica containers which transmit hard UV that heats hydrogen external to the silica containers and is exhausted through nozzles, propelling the vehicle.
Silica has very poor thermal conductivity, which means it can't be cooled readily by conduction. This means that the inner container wall will melt even if the outer wall coolant is liquid hydrogen because the wall material can't transport the heat flux. One might be able to keep a 10µm silica shell from melting, but nothing thicker. Too thin to be mechanically sound.
Also, the uranium hex will be completely dissociated and ionized at 25K°C. This means the inner silica wall will be exposed to atomic fluorine, and will corrode away immediately. Uranium at 25k°C probably reacts with SiO2, but I don't know that. Uranium silicides and oxides are known compounds, so it's likely. It's a horrific corrosion environment. At temperatures like this, everything reacts with everything else.
In short, this nuclear lightbulb can't be built with any material we currently know of. We'll have to wait for Scotty's transparent aluminum.
Perhaps the MIT drone could use a Stirling engine with a Pu238 RTG heat source and air as the working fluid. If so, it could stay up forever. I'd bet on that before the nuclear light bulb.
> Perhaps the MIT drone could use a Stirling engine with a Pu238 RTG heat source and air as the working fluid. If so, it could stay up forever.
Radioisotope thermoelectric generators only output something like 250W up to a max of 600W. Not nearly enough for sustained flight of something this size. Also, if you think the licensing and permitting process is hard for a regular drone, take a look at the amount of paperwork and security related to all of the RTG powered spacecraft/probes launched in the last 30 years. Pu238 is, to put it mildly, a somewhat controlled substance.
Presumably it relies on a boundary layer of cool uranium hexafluoride, and very low mixing of the gas.
Make the design large enough with a low enough pressure, and it sounds like you could make the heat flux manageable. The boundary layer will also protect the quartz from the atomic effects of the uranium ions - they will cool and recombine before reaching the quartz.
The hydrogen side will want much higher pressure (to be able to absorb enough UV, since a UV reflector sounds hard to cool)
Assuming the biggest transfer of energy in the hydrogen and uranium gasses will be convective, so making the quartz spin you could use the higher density of cool uranium gas to keep your quartz cool. The hydrogen side is flowing, so as long as you keep the flow laminar, one can use a cold boundary layer again.
The hydrogen propellant (or water in the case of a terrestrial reactor) is seeded with tungsten nanoparticles which absorb UV like nobodies business, eliminating the need for the high pressure hydrogen.
The boundary layer is actually neon, which is injected to form an irrotational vortex (the opposite of a tornado) that pushes everything to the center at high pressures.
> Has anybody thought through the engineering of those silica reaction vessels (I haven't searched)? I don't think it can work.
> If I understand the concept shown in the Wikipedia page, it depends on uranium hexafluoride operating at 25,000°C in fused silica containers which transmit hard UV that heats hydrogen external to the silica containers and is exhausted through nozzles, propelling the vehicle.
> Silica has very poor thermal conductivity, which means it can't be cooled readily by conduction. This means that the inner container wall will melt even if the outer wall coolant is liquid hydrogen because the wall material can't transport the heat flux. One might be able to keep a 10µm silica shell from melting, but nothing thicker. Too thin to be mechanically sound.
The wikipedia article is actually pretty terrible when it comes to the specifics, as if whoever wrote it just read the abstract of one paper (there were at least 50 IIRC). They used fused silica in the early proof of concept (without nuclear fuel) because they were still proving the basics like the irrotational vortex injectors and compression of the core. The technology for making extremely pure single crystal beryllium oxide has since been developed and has found commercial applications, especially in aerospace and semiconductors. Single crystal BeO has far better thermal conductivity and UV transparency, making it possible to cool the reactor walls fast enough.
The bigger problem is neutron bombardment which rapidly degrades the containment chamber's transparency and without replacing the neon with water (impossible), there's no way to counteract that. However, since the reactor is so easy to shut down (stop injecting neon and open the exhaust vents), even weekly or monthly replacements become economically feasible. All of the equipment needed for it are already part of the design (centrifuges for separation of the gas + fuel, modular reactor instead of solid piece of steel/concrete, etc.). The nuclear lightbulb design is unique because all of the other factors that make classic nuclear fission so expensive are eliminated (redundancies of active safety measures, meltdown-proof shielding, etc.) so there's a lot more money to spend on the actual operation and maintenance of the reactor.
Furthermore: the program was canceled before they started the research but they had plans to investigate ways of generating power from the reactor through magnetohydrodynamics instead of turbines/photovoltaics. The whole field was still in its infancy at that point but they had some ideas to test that would have replaced the transparent containment vessel with much stronger (and cheaper) reflective material, eliminating the hardest part of the design.
> Also, the uranium hex will be completely dissociated and ionized at 25K°C. This means the inner silica wall will be exposed to atomic fluorine, and will corrode away immediately. Uranium at 25k°C probably reacts with SiO2, but I don't know that. Uranium silicides and oxides are known compounds, so it's likely. It's a horrific corrosion environment. At temperatures like this, everything reacts with everything else.
The pressure applied on the core is (if I remember correctly) in the hundreds of atmospheres, if not thousands, with an absurd angular momentum. The vast, vast majority of particles that are shaved off of the core cool extremely quickly and are either sucked out or pushed back into the core. Any corrosion feeds into the above maintenance schedule and there was some discussion about seeding the neon with other elements to moderate chemical reactions.
If you can access them, I highly recommend reading at least the big summary paper. All of these problems were discussed, many were even tested, and solutions were found that require technology we have developed by now. All of the problems you brought up were at the top of their minds because they were designing the nuclear lightbulb primarily as a rocket engine where maintenance would have been impossible.
Nope, it's literally 25,000 degrees C. The higher the temperature and density, the less mass you need to reach supercritical so to get to the point where 20kg is fissile, you need to really turn it up. Increasing the density of a ball of uranium plasma is far harder than just heating it up some more.
Why do you need to cool the reactor? I thought the whole point was the reactor was hot - that was how you got useful energy from it. Doesn't using the heat energy dissipate it?
Also, if you care about mechanical stability (an engine, not a bomb), you either cool the reactor down to temperatures of its containment material (all attainable solid materials are limited to a few thousand K), or use something like magnetic containment, which is not always an option (you need everything inside electrically charged, and a low neutron flux).
> Direct cycle nuclear engines would resemble a conventional jet engine, except that there would be no combustion chambers. The air gained from the compressor section would be sent to a plenum that directs the air into the nuclear reactor core. An exchange takes place where the reactor is cooled, but it then heats up the same air and sends it to another plenum. The second plenum directs the air into a turbine, which sends it out the exhaust. The end result is that instead of using jet fuel, an aircraft could rely on nuclear reactions for power.
A direct cycle design (which is the only one that was ever thought practical to use) passes outside air through the core for cooling purposes, then sends it through the exhaust.
> Indirect cycling involves thermal exchange outside of the core. The compressor air would be sent to a heat exchanger. The nuclear reactor core would heat up pressurized water or liquid metal and send it to the heat exchanger as well. That hot liquid would be cooled by the air; the air would be heated by the liquid and sent to the turbine. The turbine would send the air out the exhaust, providing thrust.
An indirect cycle design doesn't expose outside air to the core, but "never came anywhere near producing flight-ready hardware", presumably because the amount of water needed for cooling would have required an absurdly large plane and even more power, leading to recursive issues.
That's neat, but not very revolutionary. The Rutan Voyager flew for 9 days (around the world) without refueling back in the 80s - https://en.wikipedia.org/wiki/Rutan_Voyager
That craft had two pilots onboard, this one had a single remote pilot. It's a real challenge to design a small craft that maximizes payload and minimizes fuel consumption along with scores of other constraints.
Voyager also needed a long runway for launch and probably costs vastly more than this drone. Its use case as an emergency communication device is revolutionary.
To be frank, for the non-Americans who read the article; the first thought would be that the drone is actually using some form of 'gas' and not liquid petroleum. I presume 'gas' in this context means gasoline and not LPG.
Well they inadvertently proved once again just how energy-dense and how incredibly ridiculously efficient liquid petroleum fuels are and what a boon and a curse they've been to humanity during this brief one-or-two-century blip, and how difficult it will be to replace them with anything that could even come close to current levels of energy output/consumption.
If you have a truly ridiculous amount of electricity, such as from a multi-megawatt scale photovoltaic system that was almost free to install, or from a theoretical very high power/low cost nuclear reactor... You could electrolyze seawater into hydrogen and store it in tanks. Doesn't necessarily have to be fossil fuel.
> Cover a 20 x 20 km section of Libyan desert with ground mount 360W PV panels, there's your power source.
Sure, but first you need to find a desert in a relatively stable country, and then you have to account for the fact that the panels will need to be cleaned.
UAE is building lots of solar, if you've been through DXB or AUH you've probably seen the Total [0] ads for solar. However I know from personal experience that even in the desert you need to have methods to clean the panels or they will be covered in dust/sand after some time, and this significantly reduces their output. [1]
You can always synthesize gas (or use hydrogen as replacement, if your system can deal with the associated problems). Liquid fossil-based stuff is where the problem lies.
Yeah but that's fuels, they're relatively simple compared to the vast amount of stuff e.g. the plastics industry needs... and it doesn't scale at the moment.
Confused. There seem to be plenty of drones that can stay up there for 120 hours or so [1]. Presumably, their solar additions should be able to do even more?
Precisely. This is an incredibly easy problem to solve. See all the Rutan projects, the model plane that crossed the atlantic, etc; most from over a decade or more ago.
They claim that solar efficiency is not there yet, but look at the NASA Helios. Yes, it's large, but such is life if you want solar. The math behind it is incredibly simple.
Yet, as usual, HN is foaming at the mouth because it has the word drone in the title.
Edit: this is just another MIT fluff piece. Watch the video, it's a carbon fiber tube filled with random COTS hobby grade components. With a hot wire and some composites knowledge you could make this in your garage.
I'm aware, I agree that solar aircraft is not an easy technology. I'm mostly pointing out how inane this gasoline drone project is when there are real problems to solve. To put it in perspective, the Helios project was 18 years ago and the Solar Impulse project improved upon the tech significantly.
Edit: just got a chance to look at the report. Thanks for the link, there are some really interesting findings in there.
Could you kindly reply with your email, as I would like to email you. I am a crank inventor (no but keep reading, just three and a half more paragraphs!) who has invented something similar to a free-energy machine, except in the field of aviation and specifically renewable energy flight, where free power is in the skies for anyone so it's not totally cranky. After all you just wrote a 27-page draft about it. (By the way your paper is very solid and prominently describes in detail several trade-offs that I address specifically through a different mechanism; you are the real deal.)
I would like to work with a collaborator (such as yourself) and then patent and license the technology. Specialist patent offices I contacted said that they would have a conflict with their existing large clients Boeing etc, and for this reason cannot work with me.
On the other hand if they do not have this experience it is kind of a catch-22. Your personal resources and if appropriate (if it works) your resources at MIT would alleviate this issue.
We can discuss the rest by email. I look forward to your reply. It will not take much of your time to make a determination. I promise it will be interesting and well-specified (usually crank inventors misuse common terminology, don't correctly understand the principles they use, and are vague and underspecified, committing logical errors and non-sequiturs to arrive at their mechanism - this isn't like that.) Thank you!
What is the general range of weight vs power levels are you producing with your device (that wouldn't reveal anything about the tech, only what sort of craft it might suit)?
What is the range of scales at which this device will work (what is the smallest, largest, optimum range for the device)?
what I had no idea... awe poor thing gotta find out what happened to it why it just broke up, also despite a flying wing being more efficient with regard to drag, why a plank? Don't they need more reflex with a shorter moment arm... anyway shit
It will bring internet, but only to the US Army as it trundles across the area and needs an over the horizon repeater to get the signal back to the uplink station.
A 5 day duration manually operated drone is clearly not going to provide long term service.
I'm sorry to have to be negative on this. I look at a bunch of this stuff that is DOD/Armed Forces funded and all I have seen for decades are nothing less than what I would call scams. Total waste of taxpayer money. And this isn't universities only, it's companies that win stupid-as-fuck "research" grants and produce crap in return.
There are a few companies out there playing with what are nothing more than ridiculously expensive toy RC planes (< 6 ft wingspan) that almost anyone could build out of parts available in the open market.
This MIT thing is nothing less than an overgrown model airplane. It uses what looks like a stock 4 stroke model airplane engine with a stock model airplane propeller. It probably uses stock model airplane servos, electronics and 2.4 GHz TX/RX.
Oh, wait, advanced materials. Nope. I have been designing and building RC airplanes as a hobby for three decades. I was vacuum-bagging large (12 foot wingspan) glider wings from fiberglass, carbon fiber and also Kevlar twenty years ago. I still have and use my vacuum bagging setup to build planes today. I have also made custom carbon fiber propellers by CNC machining aluminum molds and stuffing them with epoxy impregnated carbon fiber rovings.
So, this is what I would call "advanced hobby" stuff.
Special airfoils? Nah. Any serious RC glider pilot who has built planes knows what airfoils to use. Not a secret. These guys didn't do anything special on that front.
Oh, but it can be taken apart and stuffed into a box for FedEx shipping. Guess what, so can any large scale RC glider. Nothing new there. Make the wing in six foot sections and you are golden.
Yeah but...
Yeah but nothing.
Here's a guy flying an OFF THE SHELF 6 meter wingspan RC glider. What do you think the wings are made from?
Replace the electric motor with an internal combustion engine and a fuel tank and bingo. Again, off the shelf.
And here are a BUNCH of guys with huge gliders, powered and not, including one that has a 51 FOOT wingspan. And, look, no truck for launch, they use another large scale RC airplane to tow it up to altitude.
Here's a list of a bunch of large scale RC sailplanes you can buy off the shelf today.
Calm down, this was just a fun practical experience course for students, that is being oversold by the news article:
From the original press-release:
>Hansman and Hoburg worked with MIT students to design a long-duration UAV as part of a Beaver Works capstone project — typically a two- or three-semester course that allows MIT students to design a vehicle that meets certain mission specifications, and to build and test their design.
Obviously a bunch of undergrads aren't going to design a revolutionary new airplane.
No problem with any of this except their use of tax money to fund it.
If they need a capstone project they can pay for it themselves. Don't create a bullshit grant for something that will not be delivered. I mean, a five minute napkin calculation would quickly reveal the solar-whatever idea was nonsense. They still took the money and built exactly what the Air Force did not ask for. That's wrong in more ways than one.
Now, seriously, allow me to doubt that flying some 2 minutes a plane (model or not) that has (or has the possibility to carry) on board five days worth of fuel actually means that the engine is capable of reliably running 5 days no-stop.
So many fascinating inventions seem to be supposed to be used for search and rescue. We've had jetpacks, robot drones, this drone, robot walkers, crashable drones, even the Boston Dynamics Atlas walking robot is for search and rescue.
Is there actually a need for so many robots? Even if there is, is the market big enough to make economical sense? It seems like it's just an easy thing to imagine when you can't think of a real purpose for your robot.
Just mount machine guns and/or a rocket launcher on the Boston Dynamics walker and you'll see a real purpose for it: infantry support. Search and rescue. Right. More like "seek and destroy". They probably got the idea out of Star Wars to begin with.
The Defense Department used to just be more honestly called the War Department. Search and Rescue is how lots of inventions are sold to newspapers, Search and Destroy is probably how they get sold at military trade shows :P.
> The Defense Department used to just be more honestly called the War Department.
Not exactly; the (now subcabinet) Department of the Army used to be called the (cabinet level) War Department. The Department of the Navy used to be its own cabinet-level Department. Then a new cabinet level Defense Department was formed, the Air Force split out of the Army and made co-equal, and each of the three (two before the split) service departments made subordinate to the new Defense Department.
The future: ultra-light drones with 90% of its weight being batteries of charging during day time, so they can be operative at night. Flying 24/7, forever (e.g. zeppelin-like).
If they need batteries, this cannot be forever. Not even close. Even less if they let the batteries deep-discharge, which dramatically decreases their lifespan.
I guess that when the vehicle isn't helping deliver communications to areas impacted by natural disasters or other emergencies, the Air Force will strap an AGM-114 Hellfire package on it and have it linger over combat zones for days.
I hope these college kids are bright enough to recognize that they are building killing machines unlike anything warfare has seen before.
No, you can't. You might get paid what the courts find is fair value for use of your IP, but IP rights are not an effective to prevent government use of your work.
See 28 USC Sec. 1498(a) regarding patents, and Sec. 1498(b) regarding copyrights.
It looks like you would need to have a patent. If you manage to create a magic battery and you keep the manufacturing process a trade secret, then you could disallow government use of your work. Is that correct? They'd obviously be able to attempt to reverse-engineer your product, of course.
This got me wondering. Could they force someone to provide them with a license due to extreme circumstances? e.g. Time of war, magic battery can help us win.
Yes, they can force you to provide your goods to them in any situation they declare urgent/emergency, and at priority over all other customers, even prepaid ones.
You will get paid, it's not confiscation, but it is an offer you cannot refuse.
I'd be surprised if the situation isn't the same in every other country -- national security/defense takes a very high priority. Moreover, any truly revolutionary technology that could create a significant military advantage will be almost required to be controlled by the mil, lest the adversaries get it.
If you don't want to ever be in a situation where you could help the military of your country, you probably need to move to a country without a military. Then worry about other countries deciding to invade for your revolutionary technology.
The point is that even a patent doesn't help; unlike any other patent violation, where courts can issue injunctive relief for a violation, the only remedy allowed for a government violation is a money award for reasonable compensation for the use.
> Could they force someone to provide them with a license due to extreme circumstances?
Basically, the cited section amounts to a blanket delegation by Congress to the executive branch of the right to use patents without license, with eminent domain-like compensation after the fact for the taking. So there's no need for a particular justification, or a license.
The problem is, it's also ambiguous in practice. I used Colt which has a clause forbidding military applications (http://dst.lbl.gov/ACSSoftware/colt/license.html), and several of my customers raised concerns about it because obviously it applies to people building nuclear warheads, but does it apply to support staff in affiliated organizations? Or companies who have contracts to do logistical support for governments who have militaries? Where does one draw the line?
The future will come sooner or later. It's not like this hasn't all already been imagined.
And for what it's worth, we've been inventing efficient ways to kill people since day 1, and the people who invent those things tend to fare much better than those who don't.
And then I thought: why is that a joke? Could you save fuel keeping it aloft with a lighter than air gas and just use the fuel to move it around?