[Spaceships] getting into orbit without superscience?

[Anthony]

Originally Posted by malloyd

This is why *all* reaction engine designs have trouble getting into orbit. Chemical rockets already run hot enough containing the exhaust is an issue. So there's not a lot of space for going hotter.

Well, you can use hydrogen as reaction mass instead of combustion byproducts; that allows an ISp of around 1,400 without being any hotter than current rocket. The problem is that reactors can't generally run anywhere near as hot as a current rocket engine.