|Country of origin||United States|
|Application||low cost throttleable booster engine|
|Propellant||LOX / RP-1 (kerosene)|
|Thrust (sea-level)||4,900 kN (1,100,000 lbf)|
|Chamber pressure||177 bar|
The TR-107 was a developmental rocket engine designed in 2002 by Northrop Grumman for NASA and DoD funded Space Launch Initiative. Operating on LOX/RP-1 the engine was throttleable and had a thrust of 4,900 kN (1,100,000 lbf) at a chamber pressure of 17.7 megapascals (177 bar), making it one of the most powerful engines ever constructed. 
The TR-107 was built[when?] by TRW following the successful conclusion of the development program for the TR-106 engine, a similar throttleable engine of about half the thrust burning LOX/LH2 instead of LOX / RP-1. Tom Mueller, then VP of Propulsion Development at Northrop, was project manager for both the TR-106 and TR-107 engines.
The engine used duct-cooling of the main combustion chamber and materials that would not interact with kerosene to minimize coking.
The duct separated the fuel from the chamber wall and allowed controlled cooling of the chamber to keep the temperature of the kerosene down. This approach simplified the engine in comparison with competing designs. By eliminating the regenerative cooling circuit, many large manifolds and associated plumbing were eliminated as well, reducing potential failure modes and improving engine reliability. The TR107 engine used oxygen-rich combustion (ORSC) products to alleviate soot build-up when running the turbo pumps. The goal of the development was to produce a large, low-cost, easy-to-manufacture booster engine.