Any rocket geeks here? No? Didn't think so. But since it's my thread I can hijack it and go rogue.
See the big pipe on the left with the nozzle belching sooty smoke? That makes this an example of an open-cycle rocket engine. That kero (or whatever you're using for fuel) and liquid o2 has to get to the engine in major volume, so rocket engines use pre-burner driven turbines to spin the pumps for fuel and LOX.
The black soot here says this is what they call a fuel-rich pre-burner, which is to say it wastes a lotta fuel, unfortunately. Up to 20% of the engine's potential thrust is lost here. When you see a rocket launch, many times you'll see flames sporadically appearing and licking the outside of the thrust nozzles, and it makes you wonder if there's something going wrong. It's not. As the airflow around the vehicle bends the pre-burner exhaust back into the thrust nozzle flame, there's moments of back-burn where it ignites and tries to self-sustain...but it can't really. Too rich, too much turbulent air. It can't burn back into the pipe because the o2 has been used in the pre-burner so until it exits the system, it has no source.
The Russians blew everybody's socks off in the 60's by creating closed-cycle rocket engines, which were considered impossible at the time. They route the by-products of the pre-burner back into use in the thrust section, which sounds like a no-brainer, but materials and engineering-wise is actually pretty difficult. Wrong temp, wrong pressure, wrong ratio, etc. Plus you generally need two pumps with complex cross-feeds, more complexity and headaches. But doing so gives you a nice boost in power and efficiency.
The Russians were building the best designed rocket engines in the world in the 60's and 70's...I said best DESIGNED because while they were elegant and brilliant engineering solutions, they also tended to explode or fail semi-regularly, due to materials flaws and inconsistencies, and poor build quality. Unlike our facilities where everything had to spec and fit perfectly or be rejected, and materials science was top-notch for the times, the Russian factory workers had pretty much free reign to modify parts to fit if made incorrectly, weren't terribly concerned with details like torque specs and such, and the high temp alloys used often weren't very good quality.
So the BEST rocket engine, if you've got millions in equipment or even your butt sitting on top, is the one that's most likely to work right without blowing up or quitting. In that respect, WE built the best rocket engines of the time. [emoji106]
Oh I was gonna mention...the turbopumps on the Space Shuttle's main engines (not the solid boosters) produce around 80,000 hp to deliver the fuel and LOX to the engines.
...that's serious fuel delivery.