TR-106

TR-106

A TRW 650K low-cost pintle engine undergoes hot-fire testing at SSC's E-1 test stand.
Country of origin	United States
Manufacturer	TRW
Application	low-cost throttleable booster engine
Liquid-fuel engine
Propellant	Liquid oxygen / LH2 (liquid hydrogen)
Performance
Thrust, sea-level	2,892 kN (650,000 lbf)
Dimensions
Dry mass	00 kg (0 lb)

The TR-106 or low-cost pintle engine (LCPE) was a developmental rocket engine designed by TRW under the Space Launch Initiative to reduce the cost of launch services and space flight. Operating on LOX/LH2 the engine had a thrust of 2892 kN, or 650,000 pounds, making it one of the most powerful engines ever constructed.^[1]

The goal of the development was to produce a large, low-cost, easy-to-manufacture booster engine. The design used a single element coaxial pintle injector, a robust type of injector. It also used ablative cooling of the combustion chamber and nozzle instead of the more costly to manufacture regenerative cooling.^[1]

The use of the pintle injector allows the engine thrust to be widely throttleable, as was the case for the lunar module descent engine.^[1]

Tom Mueller was a lead engineer for development of the LCPE,^[2][3] a 650,000 lbf thrust LOX/LH2 engine. In the summer of 2000, this LCPE was successfully hot fire tested at 100 percent of its rated thrust as well as at a 65 percent throttle condition at NASA's John C. Stennis Space Center in Mississippi.^[4] TRW changed the pintle injector configuration three times during testing to explore the engine's performance envelope; engineers also replaced the ablative chamber once while the engine was on the test stand—demonstrating the LCPE's ease of operation. Test results demonstrated that the engine was stable over a wide variety of thrust levels and propellant ratios.^[1]

Development of the engine was temporarily discontinued with the cancellation of the Space Launch Initiative.^[1] In 2002 TRW was acquired by Northrop Grumman and development of a LOX/RP-1 engine (TR-107) continued, under contract to NASA, for potential use on next-generation launch and space transportation vehicles.^[5]

Tom Mueller became TRW vice president of propulsion. In 2002, Elon Musk asked Mueller to join him as a founding member of SpaceX.

Technology lessons from the Low Cost Pintle Engine project were used in the development of the SpaceX Merlin engine.^[6][7] Mueller joined SpaceX in 2002, becoming its head of propulsion, along with other TRW staffers.^[8] The turbopump, meanwhile, was contracted to Barber-Nichols, Inc., which derived their pump from their work on the FASTRAC turbopump.^[9] After SpaceX accused Northrop Grumman, TRW's parent, of letting engineers supervising SpaceX under a Pentagon contract use that information on Northrop's own rocket technology, Northrop Grumman then sued for theft of trade secrets.^[10][11] The dueling suits were settled in early 2005.^[12]

• Raptor

• Media related to TR-106 at Wikimedia Commons
• TRW Engine Development, 2000, AIAA Archived 2017-08-09 at the Wayback Machine