Most powerful single-chamber liquid-fuelled rocket engine

The most powerful single-chamber rocket motor ever built is the Rocketdyne F-1, built for the first stage of NASA's Saturn V rocket. This gigantic motor – which stood 18.5 ft (5.6 m) tall and weighed 18,500 lb (8,400 kg) – generated 1,522,000 pounds-force (6,770 kilonewtons) of thrust at sea level. Development started in 1957, and it first flew on the Apollo 4 mission (an uncrewed test of the Saturn V rocket) on 9 November 1967.

The first production batch of F-1 engines were made to a specification that required 1,500,000 lbf (plus or minus 3 percent). This was later refined to 1,522,000 lbf (plus or minus 1.5 percent). The marginally uprated engines were used from Apollo 9 onwards.

The F-1 is what's called an open-cycle, or "gas generator" motor. In this design a small amount of fuel and a proportionally even smaller amount of oxygen is fed into a gas turbine which drives the pumps that feed the combustion chamber. The fuel-rich mixture burns inefficiently compared to the mixture in the main chamber, which prevents temperatures in the turbine from rising high enough to melt the machinery.

The Russian RD-170 family of rocket motors (the 170, 171 and 171M) generate more thrust (7,246 kN; 1,628,966 lbf) than the F-1, but they comprise four combustion chambers and nozzles, linked by a shared set of closed-cycle oxidizer-rich turbopumps.