Derek Lyons wrote:

The drawing doesn't show any details of the fluid injection system of
the nozzles though, nor where the freon for it is stored.

The diagram shows the first stage, which used jetavators or rotating
nozzles. Fluid injection was used on the second stage.

My slip.
Was there some sort of ignition system at the base mounted in the center
of the four nozzles? The diagram seems to show a central hole down there
under the odd cone-shaped chunk of propellant at the base of the fuel grain.

Pat