Status: Out of production. Number: 4 . Thrust: 68.20 kN (15,332 lbf). Unfuelled mass: 173 kg (381 lb). Specific impulse: 265 s. Specific impulse sea level: 251 s. Burn time: 113 s. Diameter: 1.37 m (4.49 ft).
Gamma engines were manufactured by Bristol Siddeley and used on the Black Knight and Black Arrow launch vehicles. Propellants were High Test Peroxide and Kerosene. Black Knight used 4 chambers in two pairs on the Y and Z axes. The motors were gimbaled to provide thrust in all axes.
Black Arrow was a three stage vehicle. The first stage had an 8 chamber layout with 4 pairs of Gamma engines gimbaled as with Black Knight giving thrust in all axes. The second stage had two Gamma chambers with extended nozzles to give full expansion in vacuum. Both engines were gimbaled to provide thrust in three axes.
Thrust (sl): 64.600 kN (14,523 lbf). Thrust (sl): 6,590 kgf. Engine: 173 kg (381 lb). Thrust to Weight Ratio: 40.2196531791908.