XLR81

XLR81
Standard Agena D 108 delivery to final assembly for Gemini Agena target vehicle 5003.[1]
Country of origin United States
First flight12 July 1963 (1963-07-12)
Last flight17 April 1984 (1984-04-17)
ManufacturerBell Aerosystems Company
ApplicationUpper stage
Associated LVThor, Thorad, Atlas and Titan
PredecessorBell 8081
SuccessorBell 8247
StatusRetired
Liquid-fuel engine
PropellantRFNA / UDMH
Mixture ratio2.55
CycleGas-generator
Configuration
Chamber1
Nozzle ratio45
Performance
Thrust, vacuum71.2 kN (16,000 lbf)
Chamber pressure3.49 MPa (506 psi)
Specific impulse, vacuum293 s (2.87 km/s)
Burn time265 seconds
Restarts2
Gimbal range±2.5°
Dimensions
Length2.11 m (83.2 in)
Diameter0.90 m (35.5 in)
Dry mass134 kg (296 lb)
Used in
RM-81 Agena
References
References[2][3][4]
Model 8048

The Bell Aerosystems Company XLR81 (Model 8096) was an American liquid-propellant rocket engine, which was used on the Agena upper stage. It burned UDMH and RFNA fed by a turbopump in a fuel rich gas generator cycle. The turbopump had a single turbine with a gearbox to transmit power to the oxidizer and fuel pumps. The thrust chamber was all-aluminum, and regeneratively cooled by oxidizer flowing through gun-drilled passages in the combustion chamber and throat walls. The nozzle was a titanium radiatively cooled extension. The engine was mounted on a hydraulic actuated gimbal which enabled thrust vectoring to control pitch and yaw. Engine thrust and mixture ratio were controlled by cavitating flow venturis on the gas generator flow circuit. Engine start was achieved by solid propellant start cartridge.[5]

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