|Country of origin||United States|
|Application||Reaction control system|
|Propellant||NTO / MMH|
|Thrust (vac.)||440 N (100 lbf)|
H-II Transfer Vehicle
A R-4D thruster is a small hypergolic rocket engine originally designed by Marquardt Corporation for the Apollo moon program. Today, Aerojet Rocketdyne manufactures and markets modern versions of the R-4D.
Developed as attitude control thruster for the Apollo Service and Lunar Modules in 1960s, each unit for the modules employed four quadruple clusters (pods). It was first flown on Apollo 201 in February 1966. Approximately 800 were produced during the Apollo program.
Sixteen engines just like this were mounted on the exterior of each lunar module in four quadruple clusters and sixteen on each service module. Because both the lunar module and service module were jettisoned during the Apollo missions, no flown examples exist.
The thruster is currently employed in the R-4D-10 version of the U.S. Navy's Leasat, R-4D-11 by Insat 1 and Arabasat 1, R-4D-12 by HS-393, Intelsat 6, Italsat, and Olympus and Eurostar. Burn Time can be up to 1 hour continuous with a 2.67 Ns min impulse.
It has been used on a number of later spacecraft, including Japan's H-II Transfer Vehicle and the European Automated Transfer Vehicle, both of which deliver cargo to the International Space Station.
- "Bipropellant Rocket Engines". Aerojet Rocketdyne. Retrieved 7 May 2014.
- Stechman, Carl; Harper, Steve (July 2010). "Performance Improvements in Small Earth Storable Rocket Engines". 46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference (AIAA). "Derivates of this engine are still used today on satellites and spacecraft including the European autonomous transfer vehicle (ATV) and the Japanese H-2 transfer vehicle (HTV) propulsion systems and the future Orion service module.
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