Hello everyone,
In researching a social history of unmanned spaceflight, I am stuck on (yet another) conundrum: who, praytell, first came up with the concept of a ullage motor, to settle fuel in a weightless upper-stage?
Right now I have it that it's the Soviets, in working out the bugs on their Molniya launcher, but what do people think?
Thanks much,
Jay Gallentine