From Wikipedia, the free encyclopedia
Jump to: navigation, search
Country of origin United States
Manufacturer Kaiser Marquardt
Application Reaction control system
Liquid-fuel engine
Propellant NTO / MMH
Cycle pressure-fed
Thrust (vac.) 440 N (100 lbf)
Thrust-to-weight ratio 13.74
Chamber pressure 6.84
Isp (SL) 312s
Used in
Orion (spacecraft)
H-II Transfer Vehicle
Space Shuttle
Apollo (spacecraft)
Cassini (spacecraft)

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.[1]

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.[2]


  1. ^ "Bipropellant Rocket Engines". Aerojet Rocketdyne. Retrieved 7 May 2014. 
  2. ^ 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.