Jet engine first stages
Simon Rowland
only can jet fuel be stored more densly then H2, but it can take the O2
out of the air, then when it's too high to operate, the jets are
jettisioned and rockets take over. Or even the fuel could still be LOX
and LH2, but with a tiny LOX tank and a normal size LH2 one. The rockets
just feed off the air for the oxygen, then when the air gets too
tenuous, it starts using the stored LOX. Makes sense to me (since 81% of
the fuel weight is LOX)...
Dani Eder
Because 'people' don't build launch vehicles. Most of them have been
built by government agencies as derivatives of ballistic missiles
that were first designed in the 1950s. In the 1950s jet engines were
considered for launching things, but they only had a thrust/weight
of around 4 or so, which was too low to be useful. They figured
out back then that you needed a T/W of around 10 for a good jet
booster. Well, guess what, such jet engines are now available.
Last year we studied a jet-boosted launcher using P&W F100-229
jet engines (the engine in the F-15 fighter). It works just fine,
taking you up to 50,000 ft and Mach 1.7. Since this engine on
full afterburner has about 4 times the fuel efficiency of a rocket
engine, your best performance is achieved by running pure jet
propulsion until you run out of air, then dropping the jets and
lighting the rocket engines.
Unless you want to spend a lot of money, you wnat to stick with
existing engines. Engine development, be it car, jet, or rocket,
is an expensive proposition.
Dani Eder
William B Patterson
On Thu, 14 Sep 1995, Dani Eder wrote:
>
> Because 'people' don't build launch vehicles. Most of them have been
> built by government agencies as derivatives of ballistic missiles
> that were first designed in the 1950s. In the 1950s jet engines were
> considered for launching things, but they only had a thrust/weight
> of around 4 or so, which was too low to be useful. They figured
> out back then that you needed a T/W of around 10 for a good jet
> booster. Well, guess what, such jet engines are now available.
Why not put your engines on the tips of large rotor systems and gently
lift your upper stages to 25000 ft or so. We lifted a 250 lb human powered
helicopter with two 3 lb thrust propellors on the tips of 50 foot radius
rotors.
Bill
DavidA5625
lift your upper stages to 25000 ft or so. We lifted a 250 lb human powered
helicopter with two 3 lb thrust propellors on the tips of 50 foot radius
rotors. "
This, of course, is the Roton concept, which would use rotors to lift
a Single Stage to Orbit vehicle to 40,000 ft, at which point the rockets
on the rotor blades would fire the vehicle into orbit.
There all sorts of alternative means of acheiving orbit - the trick is
to actually build them, rather than just talk about them.
David Anderman
Space Activist
916/421-2621