So this gif of a space shuttle main engine starting up:
https://m.imgur.com/gallery/tgZ2WgA
The engine bell here is 2.4 meters in diameter. It's burning 1,300 liters of fuel per second and throwing the exhaust gas out at 3.6 kilometers per second.
Space travel is hardcore.
@starkatt And its fuel is hydrogen and oxygen; the only exhaust product is water vapor.
@kelseyhusky @cynosura If you're curious, this video is a good introduction to the subject!
"KSP Doesn't Teach: Rocket Engine Plumbing" -- Scott Manley [16:18]
https://www.youtube.com/watch?v=4QXZ2RzN_Oo