Country of origin | United States |
---|---|
Manufacturer |
Kaiser Marquardt Aerojet Rocketdyne |
Application | Reaction control system |
Liquid-fuel engine | |
Propellant | NTO / MMH |
Cycle | Pressure-fed |
Performance | |
Thrust, vacuum | 110 pounds-force (490 N) |
Thrust-to-weight ratio | 13.74 |
Chamber pressure | 100.5 pounds per square inch (6.93 bar) |
Specific impulse, vacuum | 312 s |
Dimensions | |
Length | 12.00 inches (30.5 cm) |
Diameter | 6.00 inches (15.2 cm) |
Dry weight | 8.00 pounds (3.63 kg) |
Used in | |
Orion (spacecraft) H-II Transfer Vehicle Space Shuttle Apollo (spacecraft) Cassini (spacecraft) ESA Automated Transfer Vehicle |
The R-4D is a small hypergolic rocket engine, originally designed by Marquardt Corporation for use as a reaction control system thruster on vehicles of the Apollo crewed Moon landing program. Aerojet Rocketdyne manufactures and markets modern versions of the R-4D. [1]
Developed as an attitude control thruster for the Apollo Command/Service Module and Lunar Module in the 1960s, each unit for the modules employed four quadruple clusters (pods). It was first flown on AS-201 in February 1966. Approximately 800 were produced during the Apollo program. [2]
Post-Apollo, modernized versions of the R-4D have been used in a variety of spacecraft, including the U.S. Navy's Leasat, Insat 1, Intelsat 6, Italsat, and BulgariaSat-1. [3] It has also been used on Japan's H-II Transfer Vehicle and the European Automated Transfer Vehicle, both of which delivered cargo to the International Space Station. [4] It is also used on the Orion spacecraft. [5]
The R-4D is a fuel-film cooled engine. Some of the fuel is injected longitudinally down the combustion chamber, where it forms a cooling film. [6]
The thruster's design has changed several times since its introduction. The original R-4D's combustion chamber was formed from an alloy of molybdenum, coated in a layer of disilicide. [2] Later versions[ clarification needed][ when?] switched to a niobium alloy, for its greater ductility. Beginning with the R-4D-14,[ when?] the design was changed again to use an iridium-lined rhenium combustion chamber, which provided greater resistance to high-temperature oxidization and promoted mixing of partially reacted gasses. [6]
The R-4D requires no igniter as it uses hypergolic fuel.
It is rated for up to one hour of continuous thrust, 40,000 seconds total, and 20,000 individual firings. [6] [7]