Bristol Siddeley Gamma

Gamma 301

Black Knight tail showing engines
Application	1st stage booster
Predecessor	Gamma 201
Successor	Gamma 8
Liquid-fuel engine
Propellant	Hydrogen peroxide / kerosene
Mixture ratio	8:1 (approx.)
Cycle	Gas-generator
Configuration
Chamber	4, gimballed in opposed pairs
Performance
Thrust, sea-level	17,000–21,600[3] lbf (76–96 kN)-21,000 lbf (93 kN)[4]
Specific impulse	250 seconds (2.5 km/s)
Burn time	120 seconds

Gamma 2

Gamma 2 rocket engine, used for the second stage
Application	2nd stage
Predecessor	Gamma 301
Successor	Larch (rocket engine)
Liquid-fuel engine
Propellant	Hydrogen peroxide / kerosene
Cycle	Gas-generator
Configuration
Chamber	2, extended
Performance
Thrust, vacuum	68.2 kN (15,300 lbf)[5]
Thrust, sea-level	64.60 kN (14,520 lbf)[6]
Burn time	113 seconds [7]

Gamma 8

Gamma 8 rocket engine on Black Arrow 1st stage
Application	1st stage booster
Predecessor	Gamma 301
Liquid-fuel engine
Propellant	Hydrogen peroxide / kerosene
Cycle	Gas-generator
Configuration
Chamber	8, gimballed in pairs
Performance
Thrust, sea-level	52,785 lbf (234.80 kN)[8]
Burn time	125 seconds

The Armstrong Siddeley, later Bristol Siddeley Gamma was a family of rocket engines used in British rocketry, including the Black Knight and Black Arrow launch vehicles. They burned kerosene fuel and hydrogen peroxide. Their construction was based on a common combustion chamber design, used either singly or in clusters of up to eight.

They were developed by Armstrong Siddeley in Coventry, which later became Bristol Siddeley in 1959, and finally Rolls-Royce in 1966.^[9]

Engine static testing was carried out at High Down Rocket Test Site, near The Needles on the Isle of Wight (50°39′38.90″N 1°34′38.25″W / 50.6608056°N 1.5772917°W / 50.6608056; -1.5772917).^[10][11] (Spadeadam in Cumbria wasn't used for testing until Blue Streak, after Gamma).