Alright, I have a question about potential performance of an engine
I'm thinking of, for those out there more versed in physics or
aerospace engineering than myself (should be most of y'all, heh).
I've heard of ejector ramjets or ducted rockets as a relatively simple
mechanism for greatly improving the performance and isp of a rocket in
an atmosphere. Basically you setup a great big ramscoop around an
engine so it sucks in the air to use as additional working mass and
free oxidizer by having a fuel rich rocket exhaust mixing in there.
And it's better than a ramjet, since it can still provide thrust at
zero starting speed, and once it's out of atmosphere or above ramjet
mach numbers, by simply operating as a rocket.
I was wondering if I could get some genuine performance specs, as the
only thing I've seen is a vague statement on wikipedia about
effectively doubling the isp of a conventional solid rocket.
Supposedly the proposed Soviet ICBM Gnom used this kind of engine to
achieve it's extreme lightweight (to the point it could be toted
around on the back of a heavy tracked vehicle somewhat rapidly).
Now, an idea I had though, is essentially this: What sort of
performance could you get out of combining this with an Nuclear
Thermal Rocket like DUMBO or MITEE? They would seem an ideal mating,
considering the excellent performance of NTRs compared to chemical
rockets, plus the fact that most proposals maximize their exhaust
velocity by using pure hydrogen as fuel. So in chemical terms it would
seem to be about as fuel rich an exhaust as you could get. So would
this actually combine the benefits of LANTR for ground launch without
having to carry along any heavy oxidizer? Or is there some serious
fundamental flaws in this?
Could it double the already impressive isp of an NTR? Would this make
an ideal engine for a near term very hard sci-fi SSTO vehicle?
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