May I be so bold as to redirect you here, and an absorbing read on Atomic Rockets?
Orbit Transfer Vehicle at Atomic Rockets
Image credit: Convair
Image source: SDASM Archives
OTV in LLO w/ LSOC and LMs in BG
Tag: lunar orbit
S-79-35177
Orbit Transfer Vehicle at Atomic Rockets
Image credit: NASA GRC
Image source: National Archives
numbers station 