Many AJ10 engine variations were developed over the years, summarized on the following table:
AJ10-37 The AJ10 engine was first used in the
Delta-A/Able second stage of the
Vanguard rocket, in the
AJ10-37 configuration. It was initially fueled by and
UDMH. An AJ10 engine was first fired in flight during the third Vanguard launch, on 17 March 1958, which successfully placed the
Vanguard 1 satellite into orbit.
AJ10-101 The
AJ10-101 engine was used on an uprated version of the Able stage, used on
Atlas-Able and
Thor-Able rockets. 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.
AJ10-138 The
AJ10-138 engine was originally developed for Vanguard and Able, and was flown from 1964 to 1980. Two of these engines were used in the
Titan III GTO
Transtage, with thrust uprated from to , and with a higher specific impulse of . Trans-Earth injection, from lunar orbit, was the most critical usage of this engine during the
Apollo program. This version used
Aerozine 50 (a 1:1 mix of UDMH and hydrazine) as fuel and
nitrogen tetroxide (N2O4) as
oxidizer, rather than the previous nitric acid/UDMH.
AJ10-118F The
AJ10-118F engine produced of thrust and was derived from the AJ10-138 engine used on the Transtage. It was used by the
Delta-F upper stage of the
Delta 1000 Straight Eight series rocket, starting in 1972. This version also used Aerozine 50 as fuel and nitrogen tetroxide (N2O4) as oxidizer.
AJ10-190 The
AJ10-190 engine was used on the
Space Shuttle Orbital Maneuvering System (OMS) for orbital insertion, on-orbit maneuvers, and de-orbiting, first flown in 1981. They produced of thrust with a
specific impulse (
Isp) of 316 seconds. Following the retirement of the Shuttle, these engines were repurposed for use on the
Orion spacecraft's
service module. This variant uses as fuel, with nitrogen tetroxide (N2O4) as oxidizer.
AJ10-118K The
AJ10-118K engine was used on the
Delta II rocket'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 the
ICESat-2 launch on 15 September 2018. ==References==