Export restricted (ITAR), sale only to US Citizens and Organizations. Desirable Marquardt R-4D rocket engine expansion nozzle and combustion chamber, measuring 5.5″ across the base and 10″ tall, with wiring connecting it to a loose ring set on top. Hand-engraved along the top: "231370, S/N 034." In very good to fine condition.
Originally designed by Marquardt to be used for attitude control, reaction control thruster on Apollo vehicles, the R-4D saw use in a variety of other spacecraft including the U.S. Navy's Leasat, Insat 1, Intelsat 6, Italsat, BulgariaSat-1, Japan's H-II Transfer Vehicle, and the European Automated Transfer Vehicle. The R-4D was also employed as the primary propulsion maneuver engine on the Lunar Orbiter. On the Apollo vehicles, the 100-pound thrust rocket engines were used in groups of four—configured as a 'quad'—to provide attitude control of the CSM and LM, allowing roll, yaw, and pitch maneuvers. A fantastic piece of significant space hardware made iconic with the Apollo lunar landings.
