[DanielBMarkham]

This entire line of thinking is very reminiscent of the Air Force's X-Plane program in the 50s.

The Air Force was heading down the road of airplane-to-orbit back in the 50s, but everybody decided that rockets were the way to go so the X-Plane (at least in terms of rocket-planes pushing the envelope of manned flight) program was abandoned.

Who knows where we would be had we kept going? If nothing else, we could have seen major improvements in heat management.