Re: Shuttle Capable of Independent Flight?

Robert Bonomi <bonomi@xxxxxxxxxxxxxxxxxxxx> wrote:
<snip>
> Postulate an "internal tank", occupying part of the cargo bay space.
> carrying fuel for the main engines. What is 'v2' for the shuttle in
> such a configuration, how much runway distance does it need to reach it?
> If it can exceed v2, then at optimum rate-of-climb, what altitude could
> it reach before running out of fuel? How much higher would/could it coast
> before the rate-of-climb went negative?

If it can land at 200MPH, it's reasonable to suspect that it could take
off at about that speed.

Total SSME thrust is about 600 tons. Orbiter weight is some 80 tons.
It will reach rotation speed in around 1.2 seconds, and hit mach 3 in
about 12. (I have doubts that the shuttle would survive, however exceeding
v2 is not a problem)

You probably don't want to light all the engines.
Assuming the top engine can be lit on the ground, alone, and that it can be
safely throttled to 50% (current limit is 65% I believe),
and that it can be gimbaled to a position where it won't make the craft
aerodynamically unstable, that'd give a thrust of 50 tons.
A more modest accelleration of about 0.6G.
It'll rotate in about 15 seconds.
Drag on the shuttle is horrible, and countering this leaves only about 20
tons of spare thrust, to keep straight and level (assuming the gear can be
raised)
However, this is still enough to accellerate at 1/4G, so if we split this
into 1/8G horizontal and vertical, it goes supersonic in about 2 minutes,
at an altitude of some 8Km.
It can probably glide for another 15Km or so.
(This is horribly inaccurate, but probably in the ballpark).

During this time, the shuttle will have used about (130*50)/420 = 7 tons
of fuel.
Of this fuel, about 1 ton will be liquid hydrogen, which will take up
about 15 cubic meters of payload bay, out of a possible 300 or so.
The oxygen will take up another 5m^3 or so.
So, to hop 20Km or so, you use up at least a twentieth of the payload bay.

.

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