Raptor engine
Raptor burns liquid methane with liquid oxygen. It uses full-flow staged combustion: every drop of propellant goes through a preburner and a turbine before burning again in the main chamber.
Two turbopumps
Liquid oxygen (blue) and liquid methane (purple) each have their own pump, lifting them from tank pressure to several hundred bar.
Regenerative cooling
Before burning, the cold methane runs through channels in the nozzle and chamber walls. It keeps the metal from melting and warms up on the way.
Two preburners
An oxygen-rich preburner and a methane-rich preburner each burn their propellant with a little of the other. The hot gas spins a turbine that drives the matching pump.
Main combustion
Both hot gas streams enter the injector and burn completely at around 300 bar. Gas meeting gas mixes evenly, and no propellant is dumped overboard, so efficiency is very high.
Nozzle and steering
The throat and bell accelerate the exhaust to over 3 km/s, producing about 230 tonnes of thrust. The gimbal tilts the engine to steer the rocket.