Wow! That seems to be a remarkably good engine. Notice that the expansion nozzle does not get particularly hot and the upper plumbing continues to be cold. The cooling system and the insulation properties of this engine are impressive. The F-1 got so hot that you almost felt that you could see through the bell.
The hot gas exiting the nozzle is transparent. That means they managed to eek most of the energy from the propellant before it exited and that the combustion was fairly complete. Being really hot, it does emit light after it exits the nozzle.
This must be a hydrogen/oxygen engine since the exhaust seems to be water vapor.
The duration of this test is down right freaky. The Saturn could burn for 90 seconds before it was toast.
The people watching were a lot closer to the test stand than could be safe for watching an F-1 engine. The observers in the block house were one mile away from the test stand when the F-1 engines were tested. Sound from those babies was lethal.
Gee, and I thought there was nobody around to design engines in the US. Well, there certainly are rocket engine designers on somebody's payroll!
Water is injected into the flame chute to prevent its’ destruction. The white stuff is mostly steam.