The Rolls-Royce Pegasus was a twin-spool turbofan engine which was developed by Bristol Siddeley to power the Hawker Siddeley Harrier and the BAE Sea Harrier aircraft. The Pegasus first ran in September 1959, but its first and difficult transition from static hover to conventional flight took place on September 8, 1961. It was manufactured by Rolls Royce Plc, totaling over 1,250 engines in different versions: Pegasus 2; 5; 6, which was built for the first Harriers (19,000lbf), entering service 1969; 10; 11, which powered the RAF's Hawker Siddeley Harrier GR.3.
The Rolls Royce Pegasus was a two-shaft design, featuring a 3-stage low pressure compressor and a 8-stage high pressure compressor, driven by a 2-stage low pressure and a 2-stage high pressure turbine respectively. Unusually the low pressure and high pressure spools rotate in opposite directions to greatly reduce the gyroscopic effects which would otherwise hamper low speed handling. The engine utilizes a simple thrust vectoring system with four swivelling nozzles, giving the Harrier thrust both for lift and forward propulsion, allowing for STOVL flight.
Specifications for the Rolls-Royce Pegasus 11
Type: twin-spool turbofan
Length: 137 in (3.480 m)
Diameter: 48 in (1.219 m)
Dry weight: 3,960 lb (1,796 kg)
Compressor: 3-stage low pressure, 8-stage high pressure axial flow
Turbine: 2-stage low pressure, 2-stage high pressure
Maximum thrust: 23,800 lbf (106 kN)
Overall pressure ratio: 16.3:1
Specific fuel consumption: 0.76 lb/lbf-hr
Thrust-to-weight ratio: 6:1