An Apollo Saturn TR-204 Attitude Control engine. Engine measures 15.5″ long, with the nozzle having a 6.5″ diameter, and weighing approximately 26.5 pounds. Fabricated by Thompson Ramo Wooldridge (TRW), the nozzle and chamber are made of phenolic impregnated silica with fiberglass overwrap. The nozzle has a sprayed zirconia coating, with the propellant inlets and valves made of metal. Its design is unique—because of the requiremet for high reliability, the engine was designed with quad-redundant valves. Engine bears a George C. Marshall Space Flight Center metal label and reads, “Engine Auxiliary Propulsion Attitude Control 150 LB / Ser. No. 531 / Date: 3-65.” These engines were in service from January 1966 to July 1975 and saw application on every Saturn V Moon rocket to provide attitude control of the Third Stage during Earth Orbit and Trans-Lunar Injection. These engines also provided propulsion after third stage separation from the Command Service Module to propel the Third Stage to impact on the Moon's surface. In fine condition.- RR Auction COA.
