Andre Majorel wrote:
Since posting to sci.space.tech seems to be a no-op...

Been wondering... Rocket engine turbopumps must need quite a bit of
power. Where does it come from ?

The usual approach is to burn some of the fuel and oxidizer in a
preburner or gas generator. This produces the hot gas that drives the
turbines.

Sometimes the preburner exhaust is dumped overboard. In other cases, it
is pumped into the combustion chamber.

The entire scheme is referred to as an engine cycle. The SSME's engine
cycle is particularly complicated :-\

--
Dave Michelson