Rocketdyne LR-101

LR-101-NA-11

LR-101 Thrust chamber on a gimbal mount designed by Robert C. Truax
Country of origin	United States
Date	1958
Designer	Rocketdyne
Manufacturer	Rocketdyne
Application	Vernier Thruster
Status	Retired
Liquid-fuel engine
Propellant	LOX / RP-1
Cycle	Gas Generator / Pressure-fed
Configuration
Chamber	1
Performance
Thrust, vacuum	(Pressure-fed) 830 pounds-force (3,700 N)
Thrust, sea-level	(Tank-fed) 1,017 pounds-force (4,520 N) (Pressure-fed) 1,060 pounds-force (4,700 N)
Chamber pressure	(Tank-fed) 2.1 MPa (300 psi) (Pressure-fed) 2.45 MPa (355 psi)
Specific impulse, sea-level	(Tank-fed) 198.7 seconds (1.949 km/s) (Pressure-fed) 209.8 seconds (2.057 km/s)
Burn time	Rated for 184 Sec
Used in
Thor, Atlas, Delta

The LR-101 is a fixed thrust, single start vernier thruster developed by Rocketdyne in the mid-to-late fifties and used in the Atlas, Thor and Delta launch vehicles until 1990.

Each of these rockets used two LR-101 secondary engines to provide yaw, pitch and roll control during their ascent to space. The pair of LR-101 vernier thrusters would receive their propellant flow from the turbopumps of the sustainer engine until it was shut off. After sustainer burnout, this pair of thrusters would switch to feed off the remaining propellant, effectively becoming a Pressure-fed engine. The remaining fuel would then be spent for the last trajectory corrections and stabilization of the rocket before separating the payload.