[Spaceships] Orion space drive: launch from underwater?

[Agemegos]

Originally Posted by lwcamp

Brett didn't specify what form of fusion is being used

Indeed not. I'm trying to cover all possible bases. For what it's worth, D-T seems most plausible. But you might use an expensive and bulky aneutronic launch unit to lob the spacecraft to a safe altitude where its cheap and cheerful D-T pulse units would be not to much of a problem.