AJ10

Not to be confused withRL10.

AJ10

AJ10-118K
Country of origin	United States
Date	1957–present
Manufacturer	Aerojet,Aerojet Rocketdyne
Application	Upper stage
Status	In use
Liquid-fuel engine
Propellant	N2O4/Aerozine 50
Cycle	Pressure-fed
Configuration
Chamber	1
Performance
Thrust, vacuum	43.7 kN (9,800 lbf)
Chamberpressure	7–9 bars (700–900 kPa)
Specific impulse,vacuum	270–319 seconds (2.65–3.13 km/s)
Dimensions
Diameter	0.84 m (2 ft 9 in)
Dry mass	90–100 kg (200–220 lb)
Used in
Vanguard(Delta-A) Thor/Atlas(Able) Thor-Delta/Delta A-N, Super-Six(Stage 2) Thor-Ablestar(Ablestar) Delta0100/1000/2000/3000(Delta-F) Delta4000/5000/II(Delta-K) Titan III(Transtage) Apollo(service module) Space Shuttle(Orbital Maneuvering System) Orion(service module)

TheAJ10is ahypergolicrocket enginemanufactured byAerojet Rocketdyne(previouslyAerojet). It has been used to propel the upper stages of severallaunch vehicles,including theDelta IIandTitan III.Variants were and are used as the service propulsion engine for theApollo command and service module,in theSpace ShuttleOrbital Maneuvering System,and on theEuropean Service Module– part ofNASA'sOrion spacecraft.

Variants

It was first used in theDelta-A/Ablesecond stage of theVanguard rocket,in theAJ10-37configuration. It was initially fueled bynitric acidandUDMH.An AJ10 engine was first fired in flight during the third Vanguard launch, on 17 March 1958, which successfully placed theVanguard 1satellite into orbit.

TheAJ10-101engine was used on an uprated version of the Able stage, used onAtlas-AbleandThor-Ablerockets. The first AJ10-101 flight, with a Thor-Able, occurred on 23 April 1958; however, the Thor failed before the upper Able stage fired. The second flight, which saw the first in flight firing of an AJ10-101 engine, occurred on 10 July 1958.

TheAJ10-138engine was originally developed for Vanguard and Able, and was flown from 1964 to 1980. Two of these engines were used in theTitan IIIGTOTranstage,with thrust uprated from 7,800 lbf (35 kN) to 8,000 lbf (36 kN), and with a higher specific impulse of 311 s (3.05 km/s).

TheAJ10-137engine (20,500 lbf (91 kN) of thrust) was used in theApollo service module's service propulsion system from first flight in 1966. Trans-Earth injection, from lunar orbit, was the most critical usage of this engine during theApollo program. This version usedAerozine 50(a 1:1 mix of UDMH and hydrazine) as fuel andnitrogen tetroxide(N₂O₄) asoxidizer,rather than the previous nitric acid/UDMH.

TheAJ10-118Fengine produced 9,000 lbf (40 kN) of thrust and was derived from the AJ10-138 engine used on the Transtage. It was used by theDelta-Fupper stage of theDelta 1000Straight Eightseries rocket, starting in 1972. This version also used Aerozine 50 as fuel and nitrogen tetroxide (N₂O₄) as oxidizer.

TheAJ10-190engine was used on theSpace ShuttleOrbital Maneuvering System(OMS) for orbital insertion, on-orbit maneuvers, and de-orbiting, first flown in 1981. They produced 26.7 kilonewtons (6,000 lb_f) of thrust with aspecific impulse(I_sp) of 316 seconds. Following the retirement of the Shuttle, these engines were repurposed for use on theOrionspacecraft'sservice module.This variant usesMonomethylhydrazineas fuel, with nitrogen tetroxide (N₂O₄) as oxidizer.

TheAJ10-118Kengine was used on theDelta IIrocket's upper stage,Delta-K.It used Aerozine 50 as fuel and nitrogen tetroxide (N₂O₄) as oxidizer.The AJ10-118K engine variant was used from 1989 and retired at the conclusion of theICESat-2launch on 15 September 2018.