Feb 222022
A Douglas concept from 1963 for a large space booster that was to use both chemical and nuclear engines. The first stage was to have chemical engines; when the booster reached sufficient altitude, it would stage off and a purely nuclear stage would deliver a one million pound payload to low Earth orbit (in this case, a million pounds of liquid hydrogen for a large interplanetary spacecraft). both stages would be recovered for re-use.
*Somewhere* I have a paper that describes this at least a little bit, with a minimal diagram…
