In this 1955 US Office of Armed Forces Information and Education film,
Wernher von Braun gives a lecture to members of the US armed forces
on the fundamentals of multi-staged rockets including a manned winged
aircraft upper stage so a crew could return to Earth.
He explains to them the physics of when weightlessness occurs and the
concept of an orbiting space station :-
30 minute video :-
https://youtu.be/JK4RbeBxqso