LR89

Rocketdyne LR89 at the Evergreen Aviation & Space Museum

The Rocketdyne LR89 was a liquid-fueled rocket engine developed in the 1950s by Rocketdyne, a division of North American Aviation. It was designed to serve as a booster engine the Atlas rocket family. ^{[1] [2] [3] [4]} The LR89 was a liquid oxygen (LOX) and RP-1 (kerosene) engine. ^[5]

It was used in configurations where it worked alongside the LR105 sustainer engine to enhance thrust in the first stage of the Atlas, being jettisoned when the vehicle weight had been considerably reduced due to propellant consumption. ^{[5] [6]}

Description

The LR89 was part of a family of engines that Rocketdyne developed to power the first American ICBMs and satellite launch vehicles. ^{[7] [8]} It was a gas-generator cycle engine, in which a portion of the fuel and oxidizer is burned to drive a turbine, which powers the fuel pumps, and featured a hypergolic igniter. ^[9]

Versions

The LR89 engine underwent several upgrades throughout its operational life, resulting in multiple versions: ^{[10] [5] [9] [11] [2] [12]}

Version	Year	Thrust (kN)	Thrust (lbf)	Specific impulse (s)	Burn Time (s)	Stage
XLR89-1 [10]	1956	758.70	170,562.54	282	133	MA-1
XLR89-5 [11]	1958	758.70	170,562.54	282	135	MA-2
LR89-5 [2] [5] [9]	1960	822.50	184,905.35	290	120	MA-3
LR89-7 [12]	1963	948.00	213,118.87	294	259	MA-5

Atlas stage

The LR89 powered the first Atlas stage, in different configurations: ^{[13] [5] [14]}

• MA-1 (booster only): two XLR89-1 booster engines and two LR101 vernier engines. Used on Atlas A; ^[15]
• MA-1: two XLR89-1 booster engines, an LR105-3 sustainer, and two LR101 vernier engines. Used on Atlas B and Atlas C missiles;
• MA-2: two XLR89-5 booster engines, an LR105-5 sustainer, and two LR101 vernier engines. Used on Atlas D and Atlas LV-3B; ^[16]
• MA-3: two LR89-5 booster engines, an LR105-5 sustainer, and two LR101 vernier engines. Used on Atlas E, Atlas F and Atlas E/F; ^[17]
• MA-5: two LR89-7 booster engines, an LR105-5 sustainer, and two LR101 vernier engines. Used on Atlas SLV3, Atlas H, Atlas LV3C, Atlas G and Atlas I.

See also

• Rocketdyne LR105
• Rocketdyne LR101
• SM-65 Atlas
• Rocketdyne
• MA-5A

References

1. "Rocket Engine Evolution". National Museum of the USAF.
2. "Technical Manual: Rocket Engine, USAF Model LR89-NA-5 (Rocketdyne)". National Air and Space Museum. Retrieved 2024-10-13.
3. "LR-89 (Atlas Booster) Engine". heroicrelics.org. Retrieved 2024-10-13.
4. Sutton, George P.; Biblarz, Oscar (2016). Rocket Propulsion Elements (9th ed.). John Wiley & Sons.
5. "Rocket Propulsion Evolution:5 - Atlas Missile". www.enginehistory.org. Retrieved 2024-10-13.
6. "LR-89 (Atlas Booster) Rocket Engine Injector". heroicrelics.org. Retrieved 2024-10-13.
7. Clark, Robert (2015-06-11). "The First Atlas Test Flights". Drew Ex Machina. Retrieved 2024-10-13.
8. Walker, Chuck; Powell, Joel (2005). Atlas: The Ultimate Weapon. Apogee Books.
9. Wade, Mark (2019). "LR89-5". Encyclopedia Astronautica. Retrieved 2024-10-13.
10. Wade, Mark (2019). "XLR89-1". Encyclopedia Astronautica. Retrieved 2024-10-13.
11. Wade, Mark (2019). "XLR89-5". Encyclopedia Astronautica. Retrieved 2024-10-13.
12. Wade, Mark (2019). "LR89-7". Encyclopedia Astronautica. Retrieved 2024-10-13.
13. Krebs, Gunter D. (2024). "Atlas Family". Gunter's Space Page. Retrieved 2024-10-13.
14. "Atlas MA engine series". www.astronautix.com. Retrieved 2025-09-14.
15. "Atlas A stage". www.astronautix.com. Retrieved 2025-09-14.
16. "Atlas MA-2". www.astronautix.com. Retrieved 2025-09-14.
17. "Atlas MA-3". www.astronautix.com. Retrieved 2025-09-14.