I don't know if this would work or not. What if you used one engine bay of an F-15 for a scramjet, the other for an SR-71 engine. That takes you to mach 10 and the edge of space. If you strapped PAM rockets to the missle racks on the wings and belly, could you make it to orbit velocity? Obviously I haven't thought the heat shield through yet, but I am just wondering over the possibilites it opens up. And obviously there is no possibility for Star Wars fighters, but the maneuvering would be done by maneuver rockets on all control surfaces.