"Ross A. Finlayson" wrote:
>
> Hello,
>
> How about a rocket that you can carry around and set on the ground,
> where it will then launch itself into space. Here I am talking about a
> rocket that weighs less than fifty pounds. It would have a
> self-contained levelling stand so it could point in the good direction
> to achieve orbit. I am thinking it would have a propellant or ion
> exhaust. If it was fusion powered, it could escape the plasma into the
> launch vesicle, and power itself from the via ramscoop once it hit
> velocity. You would have to stand fifty or a hundred meters away.
Alternate approach: give it wings sufficient to take off from a
commercial airport. Much easier integration into existing aerospace
infrastructure that way, even if the wings aren't that useful once in
orbit. Even non-fusion-powered plasma might be doable to achieve
orbit, since you'd only have to supply a few minutes of power from
batteries or capacitors.
The challenge here would be making the engine light but powerful enough
to deliver > 1 G of thrust. Existing similar engines are designed for,
at most, .05 G, though that's mainly because they're envisioned only
for use after launch, for hours or days of constant thrust, with an
onboard power plant which would be inordinately heavy if providing
power for 1 G. I suspect one could get some useful economies of scale
as the engine gets more powerful; at worst, though, if one engine gives
X newtons of thrust above what it needs to thrust itself (including
power source, reaction mass, and structure to hold the engine) at 1 G
(or whatever launch acceleration is desired) for the launch period
(that is, however long it takes to achieve orbital velocity), and one
needs Y newtons of thrust to give the same acceleration over the same
period to the rest of the rocket, then one simply needs to mount Y/X
engines.
If this launcher could recharge in orbit (electricity via solar
panels, and reaction mass via ramscoop - though this latter one might
be too slow for practical use), it could launch with just enough power
to get to orbit plus maneuvering, then at the end of its mission,
reverse thrust and drop to near 0 velocity relative to Earth, dropping
back into the atmosphere without resorting to aerobraking (and thus,
without needing the thermal protection that aerobraking to remove
orbital velocity requires) except to bleed off the last few hundred
kmph once it gets to its landing area (just like airplanes do). Then
again, it might be better just to launch it with enough charge and
reaction mass to get to orbit and return, thus allowing mission abort
at any time (better known as "safety margin").
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:56:21 MDT