The XLR11 was the first liquid-fuel rocket engine developed in the United States for use on airplanes, and it had a long career powering important research aircraft. An XLR11 engine powered the first airplane to break the speed of sound, the Bell X-1, in 1947, and also powered other X-1 models. XLR11s also flew in the X-24A and X-24B lifting bodies and other vehicles including the record-breaking X-15s, which used two XLR11 engines mounted together during their early flights.
The XLR11, also known early in its career as the LR11, delivered a total of 5,900 pounds of thrust. It featured the ability to stop and restart its four individual chambers, but the engine was only “on-off” and not throttleable like the later XLR99 on display nearby. The engine’s propellants were liquid oxygen and a mix of water and ethyl alcohol. A pressurized system delivered propellants to the engine in early versions; later versions used turbopumps. Like later engines, the XLR11 circulated fuel around its thrust chambers to cool them before the fuel was burned.
TECHNICAL NOTES:
Thrust: 5,900 lbs. (1,475 lbs. in each of four chambers)
Propellants: Ethyl alcohol and water fuel and liquid oxygen oxidizer
Weight: 345 lbs. including turbopump
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