re: Saturn 5
I used to have the Saturn 5 model (1/96th) (no more, gone forever and I never could properly glue the LET to the cone).
Around the lower part of the SIVB, there were a number of protruding devices. It's much later I realized they were solid rocket motors meant to push the LH2 and LO2 downwards, at ignition, while it was in 0G.
OG plays tricks to fluids!