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Engine Model: LR91-11. Manufacturer Name: AJ23-140. Government Designation: LR91-11. Designer: Aerojet. Propellants: N2O4/Aerozine-50. Thrust(vac): 467.000 kN (104,985 lbf). Thrust(sl): 232.700 kN (52,313 lbf). Isp: 316 sec. Isp (sea level): 160 sec. Burn time: 247 sec. Mass Engine: 589 kg (1,298 lb). Diameter: 1.63 m (5.34 ft). Length: 2.81 m (9.21 ft). Chambers: 1. Chamber Pressure: 59.30 bar. Area Ratio: 49.20. Oxidizer to Fuel Ratio: 1.86. Thrust to Weight Ratio: 80.85. Country: USA. Status: Out of production. First Flight: 1968. Last Flight: 2005. Flown: 267.

First Flown: late 1968 Titan 3, 1989 Titan 4. Dry Mass: 589 kg. Length: 281 cm. Maximum Diameter: 163 cm (skirt outer diameter). Mounting: fixed, but turbine exhaust utilized for roll control. Engine Cycle: gas generator. Oxidizer: nitrogen tetroxide at 97 kg/sec. Fuel: Aerozine-50 at 54.7 kg/sec. Mixture Ratio: 1.86:1. Thrust: 467 kN vacuum. Isp: 316 sec vacuum. Expansion Ratio: 49.2:1. Combustion Chamber Pressure: 58.5 atm. Cooling Method: fuel regenerative thrust chamber, with separate ablative skirt. Burn Time: 247 secs.Used in Titan 4-2; Titan 3B-2; Titan 3A-2.

Engine Model: LR91-3. Manufacturer Name: AJ23-131. Government Designation: LR91-3. Designer: Aerojet. Propellants: Lox/Kerosene. Thrust(vac): 355.900 kN (80,010 lbf). Thrust(sl): 242.600 kN (54,539 lbf). Isp: 308 sec. Burn time: 225 sec. Mass Engine: 590 kg (1,300 lb). Diameter: 2.26 m (7.41 ft). Chambers: 1. Chamber Pressure: 45.00 bar. Area Ratio: 25.00. Thrust to Weight Ratio: 61.51. Country: USA. Status: Study 1957. First Flight: 1959. Last Flight: 1965. Flown: 70.

Titan 1 Stage 2 major production version.

Engine Model: LR91-5. Manufacturer Name: AJ23-133. Government Designation: LR91-5. Designer: Aerojet. Developed in: 1962. Application: Titan 2-2. Propellants: N2O4/Aerozine-50. Thrust(vac): 444.800 kN (99,995 lbf). Isp: 315 sec. Burn time: 175 sec. Mass Engine: 500 kg (1,100 lb). Diameter: 1.68 m (5.51 ft). Length: 2.80 m (9.10 ft). Chambers: 1. Chamber Pressure: 56.20 bar. Area Ratio: 49.20. Oxidizer to Fuel Ratio: 1.80. Thrust to Weight Ratio: 90.71. Country: USA. Status: Out of Production. First Flight: 1962.

Titan 2 ICBM Stage 2. Configuration: scaled down version of stage 1 engine featuring fixed single chamber. Applications: Titan 2 stage 2. Engine Cycle: gas generator. Propellant flow rate: 163 kg/sec. Mixture Ratio: 1.80.

Engine Model: LR91-7. Manufacturer Name: AJ23-135. Government Designation: LR91-7. Designer: Aerojet. Propellants: N2O4/Aerozine-50. Thrust(vac): 444.800 kN (99,995 lbf). Thrust(sl): 225.200 kN (50,627 lbf). Isp: 316 sec. Isp (sea level): 160 sec. Burn time: 180 sec. Mass Engine: 565 kg (1,245 lb). Diameter: 1.63 m (5.34 ft). Chambers: 1. Chamber Pressure: 50.00 bar. Area Ratio: 45.00. Oxidizer to Fuel Ratio: 1.79. Thrust to Weight Ratio: 80.28. Country: USA. Status: Study 1961. First Flight: 1962. Last Flight: 2003. Flown: 106.

Version used on Stage 2 of Gemini Launch Vehicle.

Engine Model: LR91-9. Manufacturer Name: AJ23-137. Government Designation: LR91-9. Designer: Aerojet. Developed in: 1968. Application: Titan III B, C, D. Propellants: N2O4/Aerozine-50. Thrust(vac): 448.605 kN (100,850 lbf). Isp: 316 sec. Chambers: 1. Country: USA. Status: Out of Production. First Flight: 1965.

Version used in earlier versions of Titan 3 upper stages.

LR91 used on Rocket Stages
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