Perhaps another possibility then is to utilise the sustainer propellant for
structural pressure support and operate the booster at higher pressures.
This would involve a more rigid sustainer propellant matrix and limit the
core geometric profile options and perhaps limit the available propellant
choices for the booster propellant which I suppose renders the idea a prime
candidate for the too-hard basket... nevertheless, I'm sure such ideas have
been investigated closely before.
Troy
of both
Unfortunately, Hawk had low-level capability, i.e. quite possible for all
burns to be at 1atm. (Although in the low-altitude case, where it didn'thave to
climb maybe 50,000ft at a steep angle, it might have been able to acceptsome
performance loss.)
Henry