Re: Ramjet Powered Mach 30 Space Plane: Will it ever happen?
Mach 3 would be ok for a ramjet. No problem. The fact is a bipropellant rocket is probably simpler to design for those speeds. I think the question you are asking is: Can we build an air-breathing rocket at those speeds? Also, what kind of heating would take place within the atmosphere at Mach 30? I could do those calculations, but can say intuitively that it isn't worth it.