Hacker News Reader

They make their own exhaust in a little combustion chamber and use it to blast fuel into the primary at ridiculous volumes. SpaceX is unique in that none of the pre burn is wasted. It all ends up back in the bell instead of leaving out the side. The soviets invented it but it never made it to production. I think it flew once and exploded.

View on HN

I’m not sure I would say the exhaust is wasted just because it doesn’t go into the main combustion chamber. The exhaust of the turbo fuel pump on one Saturn V F-1 engine provides more thrust than an F-16 in afterburner.

The Raptor is the first operational Full Flow Staged Combustion rocket engine. https://en.m.wikipedia.org/wiki/Staged_combustion_cycle#Full...

Combustion cycles that run the turbopump exhaust into the main combustion chamber are called "staged combustion." The Soviets had staged combustion engines putting payloads in orbit in 1960, and the US flew its first in 1981.

SpaceX's advance was going from oxygen rich (where all of the oxidizer and a fraction of the fuel run through the preburner and turbine, as used in the Soviet/Russian engines) or fuel rich (vice versa, used in the Space Shuttle) to full flow (which has both oxygen- and fuel-rich preburners and all of the propellants flow through one turbine or the other).

Reply on news.ycombinator.com