R-4D
Cassini (spacecraft) ESA Automated Transfer Vehicle |
The R-4D is a small
History
Developed as an attitude control thruster for the Apollo
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]
Design
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]
Additional literature
References
- ^ "Bipropellant Rocket Engines". Aerojet Rocketdyne. Retrieved 7 May 2014.
- ^ a b David Meerman Scott (November 2013). "Marquardt R-4D Apollo spacecraft attitude control engine". Apollo Artifacts. Retrieved 5 February 2016.
- ^ "BulgariaSat-1". spaceflight101. Retrieved 23 June 2017.
- ^ 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.
- ^ "Artemis 1".
- ^ S2CID 111626089.
- ^ "R-4D". Astronautix. Archived from the original on August 26, 2002. Retrieved 5 February 2016.
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