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Has anyone heard about the mono atomic nitrogen rockets that were perposed back in the 60s 70s? I read about them once and then couldn't find it again. If I remember right the idea was to use the monoatomic nitrogen in the upper atmosphere to get the energy and maybe propellent to get to orbit. I don't really understand how that would work since the density is so low, but if they are monoatomic, would they have an electric charge? If so, perhaps a large charge on board the rocket could attract them? The energy released should be theoretically pretty large, no, going from unbonded to a triple bond?
If pure gas expansion is not going to work, then why not use liquid hydrogen and liquid oxygen together? The hydrogen would ceirtinlly vaporize, but giving it's high heat capacity, it would definetly freeze the oxygen, no? If they were sprayed into a vessel at the same time, at a high pressure, would it be possible to have the hydrogen gas trapped in the solid oxygen, so that it could a chunk of solid fuel? I realize that oxygen is non-polar, but is there anything akin to a hydrate that could be formed, or maybe just many small bubbles in the ice?
I don't see why not on eath except that the exhuast would probably be toxic and the isp is pretty low. Insulation is a problem if you to hold it around for a while, you can't just let a little boil off with a solid rocket. I would like to see a solid oxygen/ hydrocarbon rocket. If you had a large carrier plane with liquid oxygen tanks inside it, could you spray the oxygen out into the empty tank with maybe methane and the rapid expansion cause it to freeze right before you are ready to launch? We do this all the time in the lab with CO2 to make dry ice, but it's probably be harder with LOX. Maybe if you were spraying liquid hydgrogen in at the same time, and the lox could crystlize around the liquid hydrogen. That would give you excellent isp and the lack of moving parts might make it worth considering.
As you threw the particles out the front, woudn't the spacecraft move backwards from the reaction, just like our rockets do now? It sounds to me like the relitivistic rocket in reverse.
Americium would work, but it goes super critical at a very small mass, has all the normal problems with radoactive waste, and won't genorate any net energy because it is produced from urainum with neutron bombardment, so it'd probably only be useful on some sort of exotic probe engine. http://en.wikipedia.org/wiki/Americium
Radon is an even numbered element, which if I remember correctly, makes it very hard to fission. It also would have the normal problems of radioactive decay with the products http://en.wikipedia.org/wiki/Radium
I think a better canidate might be the photofission of lithium, which does yield net energy because its protucts are helium-4 and hydrogen-3, helium-4 being more stable. From this chart http://en.wikipedia.org/wiki/Image:Bind … otopes.svg it looks like it might yield more energy per mass than uranium, so the whole process migh break even. Hygrogen -3 would be the only radoactive waste, which shouldn't be too bad as it has a half life of 12 years, and vented into the upper atmosphere it's not going to hurt anyone.
I think the SRB could be inproved on with new materials, I mean steel is cheap but if you are reusing it, that isn't such an issue. Basalt fiber and fiberglass cost about 3.00$ a Kg and there are epoxy materials that can handle temperatures up to 1300 c. Another thing to consider is how much staging are you going have to clusters, like all the side boosters falling off together or two by two.
something like this might be good for the upper stage http://www.dunnspace.com/self_pressurized_rockets.htm
I don't really like hybrid rockets as mixing the fuel isn't as easy, but they do have the advantage of being able to turn off. As for calculating the payload- http://en.wikipedia.org/wiki/Rocket_equation is a good start.
Well, my pet big dumb launcher is probably way too dumb but here it is, no moving parts on the main propulsion system- a mix of plastic (hydrocarbons) and high test hydrogen peroxide frozen solid, (~4 C) in a basalt fiber fabic tube. No epoxy, just a layer of plastic underneath the basalt fiber fabric sewn shape. The fuel, and during flight the pressure would keep the shape. One engine a the bottom made of basalt fiber (working temp ~1000 C) and some ablative cooling. For directional control you have a hydrogen peroxide/ propane stage (vaper pressure so no pumps) on top of that with four nozzels that can rotate 90 degrees from straight down to sidways. Then they don't have to throtel and can be used together as the abort system and upper stage. Tow the whole thing in the ocean past the 200 km limit with a tug boat to avoid launch pad costs and pesky regulators.
I do like the idea of a of small tanks clustered, but since I'm counting on a burn through of the pressure wall of the first stage, you'd probably need liquid fueled rockets.
Paris, is a really big rocket, using current technology, right? I'm not sure there's a market for that right now. We can get big things into space, the space shuttle weighs about 100 tons, and the new ares V will be able to have that much payload too, so unless you need something really large sent up in one piece, it'd be cheaper to build it in sections, then the flight rate can be higher and you can at least have the benifits of mass production for the tanks and whatnot. Some thing worth investigating however, we can make fantastic rocket engines- like the SSME, but they cost way too much to be used on a comercial rocket, though they are very efficent, and we can make dirt cheap rocket engines, like the ones in bottle rockets for fireworks, but though cheap they are too inefficent to be used on a comercial rocket, so there must be a certian cost per engine effecency that is the best, but maybe some one has already done this? Seems to mee that maybe current rockets use too effecent of engines.
Opps, I guess I was wrong, you can stimulate fission with external sources like lasers, but aparently it doesn't break even even when you use uranium.
google photofission
I think this is a facinating idea, and I looked up a bit more on Wikipedia. I don't think that Xenon will work, as what you are discribing is alpha decay from Xe to Sn, which, while possible, will not happen very rapidly given the long half life of Xenon isotopes. I haven't seen anything to sugest that this can be sped up by adding energy or by any other means, but correct me if I'm wrong.
Fission of Xe isn't theoretically impossible as it is more than twice as heavy as Fe56 (the top of the binding energy curve, and most tightley bound element) so maybe it could be split, but I have no idea how this could be acomplished, obviously neutron bombardment isn't going to be enough as that only works for Uranium and heavier elements. Fusion takes huge temperatures and pressures to overcome the electrostatic repulsion between the nucluses, but I don't know the theory behind fission.
Perphaps there are some advantages to a uranium fission reactor based on the Dense plasma focus. Mined uranium could be converted to uranium hexeflorine and placed in a low pressure vessel with the plasma focus. The capasitors are discharged and it is ionized and compressed as a plasma so that at the focus it goes super critical. The amount of uranium needed would be very low, and it could be scaleable to any size, see the link in previous post. The main asset would be that the energy could be converted directly into electricity as the end product would be an ionized gas that could be fed though a MHD genorator as this group wants to do, though running as a fusion power sorce. http://focusfusion.org/log/index.php/site/toc/what/
Another possibility may be to use it in deep space as a mini orion drive since it should be scaleable, so no shock absorbers needed. Also, the uranium may not have to be enriched. I'm not sure this is possible, is the density great enough to go supercritical, will the uranium hexeflorine simply breack down, will it break even energy wise, but it dosen't seem totally impossible.
This sounds like an interresting idea, but what advantage would it hold over a conventional nuclear reactor? Other than being easier to get the fuel for on mars? I doubt the ammount of tin produced would be significant.
As for starting the reaction, I think this would be very difficult if not impossible. I'm not a nuclear physicst, but in a conventionally fueled reactor a suffent mass has to be brought together for it to go supercritical. I suspect this has to do with density too, which isn't a problem if you are using a dense metal like urainum, but with a gas, the pressure would have to be enormous, no?
You mentioned using lasers to start fission, but I have a hard time seeing how that would work, a laser ciertenly is not going to have enough energy to break apart an atom's nucleus and release neutrons, unless we are talking fussion style pulsed lasers, in which case you might as well just do fusion. Probably some fast neutron sorce would be more practical- don't some radioactive isotopes emite neutrons.
here's something that may be of intresst as well- fision in a plasma
http://en.wikipedia.org/wiki/Plasma_focus
edit- sorry the link is a neutron source from fusion not nuclear fission
As for having a zillion small engines, I can't imagine that it would be effiecent, but if you had enough, you could still make it to orbit without some of them, so what you really need to count is how ofter they fail explosively. I really don't know how often that happens, but if it's only a small fraction of the time, then it might be a bit more fesible.
I've always been partial to solar thermal, but only because it might be easier to build one in-situ that to enrich uranium, (other wise I'm all for NSWR) Maybe to get a better isp you could use some variant of ablative laser propulsion. Either a solar pumped laser (cooling could be a big problem) or use some fancy cooled secondary mirrors to have the focus of a constant source of light pan across the propellent block to simulate the fast pulses needed. I have no idea if that is possible, but it could give some fantastic isp (up to 20000). The paper I saw it in seems to have a dead link now, but here is a google cache without the pictures-
that might work, I saw a proposel for something like that a couple years ago, but it was unmaned. The main problem I can see with aquaculture in the middle of the ocean is that you need to re-create an entire food chain unless you can afford to import fish food grown on the land. Maybe with some iron fertilizers you could, but it makes it a lot more complex. the other question is, why whould any one what to live out there, when they could live on dry land and just do shifts like they do on oil rigs? The commute is too easy, so to speak, to colonize the oceans.
This means that a 60 atm tank could be made to hold 133 m3 for about 1400 kg and thus about 3500 USD in raw materials cost. Some decent turbopump fed engines operate at 60 atm, so no worries about a drop in performance because of low pressure and 133 m3 is enough volume to put a gross 10000 kg to orbit with a methane/lox propellent, so a reasonable payload might be 5 tons. That's with a singe stage by the way. Filiment winding seems pretty automated, so there shouldn't be too much extra cost there once the machine is built.
Neat, I wonder what the power to weight will be like. Probably too far off to tell.
Well, I guess I'd still rather fly on the Al/Lox mix. A single tank would be simpler, and if you froze the Lox (50 K) you could have a solid fuel rocket with absolutly no moving parts. Pumps wise, it'll probably be presure fed any way you cut it, now that I think about it more a high thrust to weight ratio engine probably isn't going to be nessisary in 1/6 of a g. Something like 40 would probably be fine.
I don't think it does. What you are really trying to do is make something like a tesla turbine, see wikipedia, using the boundary layer to accelerate the fuel. It's really a moot point though, why not just use the aluminum dust suspended in LOX thats already been tested? A presure fed engine would work alright on the moon, assuming you had a strong enough tank.
Launch vehicles still seem to be made almost entierly of aluminum instead of carbon composites for cost reasons, but here's a pretty new product that might change that. Basalt fiber is not quite as good as carbon fiber as far as tensile strengh and density, but if this website is to be belived it only costs 2.50 $ a kg. It also is a good insulator, cyrogenic compatible, and can handle 1000 C for short periods of time. Could this make large pressure fed rockets possible on the cheap, for tanks and engines? The problem may be the epoxy, which would add weight and might not handle extreme temperatures, but maybe a thin alumium tank or engine could be renforced with filament wraping and no or little epoxy.
http://www.basaltfm.com/eng/fiber/info.html
-density is about 2800 kg/m3
Yes, I'm sorry. In normal fluid flow, at the walls, or the thicker liquid exterior the fuilds are moving the same speed, however in a supersonic flow there is a good deal of slip, I think. I'm not sure how much of a differanc this would make. The main problem I can see is the small rocket just increasing the pressure inside the pumping area and forcing the aluminum back into the tanks. I found that the isp is about 286, but batter is you can add hydrogen or some other light gas to the exhast.
That's an interesting pump idea, however, I can see a few problems, one, at supersonic speeds, the speed of a gas next to a solid dosen't have to equal any more, so you wouldn't get as much push as expected. Second, what is the viscosity of liquid aluminum? You would have quite a bit of drag from the other wall. So, I'm not sure it would work, possibly you could just increase the pressure and it would run backwards.
Wow, I glad some one has tried that out, any idea what the isp is like?
I suppose that might work, you'd need pumps though, a low pressure engine would be pretty big and heavy. However if you really wanted to avoid pumps, how about freezing a mixture of oxygen and aluminum dust, in a solid fuel like slug, there wouldn't be a big problem with insulation if you lanched it at night. It wouls be simpiler with no pluming. Basalt fiber from the moon might make a pretty lighweight tank and it's good at high temperatures.
Sorry,
I should have posted this other link too. I'm converted. JP areospace has a shot at it with these things.
http://www.parc.xerox.com/research/publ … s/5706.pdf
Don't know what the price on these is, but at 236 suns solar concentration they have 39% efficency, and are thin and light weight to boot.
http://www.spectrolab.com/DataSheets/TNJCell/utj3.pdf
