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LTA + rocket for SSTO

LTA / rocket Single Stage To Orbit (or reentry cargo) vehicle
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If you take a Zeppelin designed to withstand G of the rocket it wraps around, you could use hydrogen for liftoff in both liquid and gaseous form. Or maybe try helium and solid fuel...This might simplify greatly launches,if all that is required is a Zeppelin hangar, rather than an elaborate launch pad with crawler, etc. You could even float away from a population center until it was safe to fire up the main burners. While I nonetheless suspect the idea lacks merit for a single-stage-to-orbit vehicle, the opposite is not true: for large-scale cargo drops from orbit (were there anything large-scale to drop (a load of H3 from someplace?)) a LTA supertanker-type reentry vehicle could be perfect and kind of makes enough sense to be inevitable until gravity is no longer a technical issue. And I'm not sure it would have to be all that sturdy...tens of gs? fives of gs? couldn't it simply sink from geosynch? (would that maneuvere be called geosink? geosynchsink? geosynchaerosink? geoaerosinksynch? geostink?) 1.) Isn't H3 gas still lighter than air? A valuable resource from upstairs...God, I'm suggesting moon blimps... 2.) Sure, a one-place vehicle might be taller than the Empire State Building...but so what? Finally a use for the deltoid pumpkin seed as a rocket plane? Regarding using hydrogen as lift gas and then liquid fuel or vice-versa...cool, but not what I had in mind. I suspect if this idea is ever deployed it would be as a reentry vehicle making one-way trip into a gravity well and steered to a salvage yard or used as a loitering instrument platform somedistantwhere. 3.) Actually large zeppelins are considered very cargo-friendly. 4.) Open flames and hydrogen rockets are ...uh... huh?
cloudface, Jul 17 2003

Similar half-baked over here: http://www.halfbake...dea/Space_20Balloon
Space Balloons! [cloudface, Oct 04 2004]


       It's not so much G you'd have to worry about, it's Q.   

       "Rockoons" are baked. However, those launch pads aren't elaborate because they're sitting on the ground; they're elaborate because they are supporting a very complicated piece of equipment. A solid-fueled sounding rocket, or perhaps even a peroxide monoprop, might be simple enough to support from a lofted platform. LH2? Forget it. And you're planning to haul the support equipment into space along with the rocket? Double that ditto.   

       (Remember, at standard temperature and ambient pressure, gaseous hydrogen won't lift enough oxygen to burn it with. Heated, it might.)   

       LTA reentry - well, if it can handle thousands of g's and millions of degrees for a matter of several seconds, I guess it would have a chance. Sounds like a single-crystal Wibnium pressurized vacuum balloon might be required.
lurch, Jul 17 2003

       Baked. What you are describing is very close to the HALO system (high altitude launch to orbit). Basicly a rocket is suspended under a balloon and carried aloft to very high alitude something like 30-40km or more.   

       Thus not having to climb through 99% of the earths atmosphere a rocket can be made very small - something the size of a 18 wheeler truck could get a two man capsule to orbit, as opposed to a 200 foot tall rocket from a ground launch.   

       It only needs to accelerate to orbital velocity. This is basicly the function of the third stage of the HUGE saturn V rockets that lifted the apollo craft. The second stage (2.5 times that of the third) and the first stage (2 times the second stage!) were just to lift the third stage out of the atmosphere!   

       An entirely LTA craft might work - if the gas bag is deflated as the hydrogen is used up. Rather like blowing up a baloon and letting it go.   

       Something like a large zeplin was quite limted in it's load carrying capacity, 90% of its weight was support structure alone. Also they had low celings as air gets thing quick. Less dense air = less lift. Made out of unobtainium, anything's possible of course.
venomx, Jul 17 2003

       One thought about using lighter than air to increase the "launch" altitude: if you do it right, you can take advantge of the high speed air currents in the upper atmosphere to give you a small boost towards your orbital velocity as well.   

       This still doesn't necessarily make this idea usable, but it's another variable that may help.   

       Another thought: the highest flying non-rocket powered vehicle (besides the ones that are classified and therefore not in the record books) was solar powered. That seemed really counterintuitive to me until I realized that it had the huge advantage of not having to carry any fuel with it. So maybe we should launch rockets from really large soloar powered airplanes. Then you get the speed boost of the wind plus the airplane velocity, plus possibly a bit more altitude than you could get from a lighter than air vehicle.
scad mientist, Jul 17 2003

       There's just not that much hydrogen in a Zepplin, no matter how big. The idea of using balloons to lift rockets to a higher altitude before ignition is an old one, and was tested experimentally by the USAF. James van Allen headed the Rockoon project in 1950. There's a contemporary project going on at http://home.hiwaay.net/~hal5/HALO/HALO_summary.shtml
mje, Oct 28 2003

       I've been passing around an idea like this. Instead of a classic rocket or zepplin shape, make it into a flying wing. Instead of carring the weight of liquid/solid fuel, use the hydrogen that is used for lift. between the gas & the wing, it should give you plenty of lift through the air. When it returns from space, it can guide down like the shuttle.
the great unknown, Nov 14 2003


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