(This has got to qualify for geek question of the week)

In the Book "Valkyire - North American's Mach 3 Superbomber" it says
in regard to the AIM-47 that the original motor the XM59 would have
been able to accelerate the missile to Mach 6 but the one actually
used the XSR13-LP-1 could only get it to Mach 4. In Chapter 3
footnote 86 it gives you credit for chasing down the designation for
the XSR13-LP-1. My question is do you by chance know what kind of
fuel the XSR13-LP-1 used and what kind the XM59 used that would give
it such a large increase in performance?


Thanks.