re: What are the problems with the hydrogen-burning ramjet shuttle?
Probably the biggest probelm is that any chemical rocket/engine just doesn't have the power to ship enough payload into orbit to be worth while. Only Nuclear power has the energy to raise significant payloads into orbit and beyond. Compare teh pay load of a nuclear light bulb rocket, 1000 to 2000 tons with the paltry payload of the space shuttle. It's time we as people wanting a real space program begin to promote nuclear power rockets.
Moon