Rolls-Royce Pegasus

This article is not to be confused with the older Bristol Pegasus radial engines

Rolls-Royce Pegasus

The Rolls-Royce Pegasus (the name comes from Greek mythology ) is a turbofan engine that originally came from Bristol and is now manufactured by Rolls-Royce PLC .

This unique propulsion system is used in all versions of the Hawker Siddeley Harrier multipurpose fighter aircraft . Rolls-Royce licensed Pratt & Whitney to manufacture the Pegasus for the US versions. The Pratt & Whitney version is called F402 , although “RR” is also given as the manufacturer's code . The Pegasus was also used as a planned engine for a number of aircraft projects such as the German Dornier Do 31 .

construction

The eight-stage high-pressure compressor

The Pegasus is a twin-shaft turbofan engine with vector thrust control. It has a three-stage low-pressure and an eight-stage high-pressure compressor , which are each driven by two-stage low-pressure and high-pressure turbines . What is unusual about the engine is that the high and low pressure shafts rotate in opposite directions to reduce gyroscopic effects at low speeds. The drive has a simple thrust vector control with four swiveling nozzles, which provide both the thrust for the lift and for the propulsion forwards, so that a STOVL flight is possible. The two front nozzles are operated with air from the low-pressure system, the rear with hot (650 ° C) jet exhaust gas. The simultaneous mobility of all four swivel nozzles was of decisive importance.

The Pegasus was also the first engine that a fan used before the actual compressor, which brought some positive effects (for example a reduction in the risk of icing).

To date, more than 1,200 engines of this type with a total of almost two million operating hours have been produced. They are deployed in the Harrier of the Royal Air Force , Royal Navy , US Marine Corps and the naval forces of India , Italy , Spain and Thailand .

history

The Bristol Engine Company began work on the BE.53 Pegasus in 1958. The engine was built in collaboration with the prototype of the Hawker Siddeley Harrier (the Hawker P.1127 , which had its first flight in 1960). It originated from the Bristol Orpheus under the supervision of Stanley Hooker . The low-pressure unit came from the Bristol-Olympus drive. Production and development of the Pegasus continued after Bristol was bought by Rolls-Royce in 1966. A related engine design was used in the Bristol Siddeley BS100 , which was intended for the planned - but not fully developed - VTOL supersonic fighter ( Hawker Siddeley P.1154 ).

variants

Pegasus 2

Also known as BE53-3, for the P.1127

Pegasus 5

Also BS.53-5 ​​(Bristol-Siddely 53-3), for the HS-Kestrel aircraft.

Pegasus 10

For the first Harrier, 20,500 lbf thrust, in service from 1971.

Pegasus 11

The Pegasus 11 is used in the first Harrier generation, the RAF Hawker Siddeley Harrier GR.3, the USMC AV-8A and later the Royal Navy Sea Harrier . The Pegasus 11 generates 93.4 kN of thrust and was used from 1974.

Pegasus 11-21 / Mk.105 / Mk.106 / F402-RR-406A

The 11-21 version with 2 kN more thrust was developed for the second Harrier generation, the USMC AV-8B and the RAF-Harrier II. The 11-21 Mk.105 used by the RAF-Harrier generate 96 kN, the Mk.106 for the Sea Harrier FA.2 97 kN.

Pegasus 11-61 / Mk.107 / F402-RR-408

The 11-61 version is the newest and, with 106 kN thrust, the most powerful version of the Pegasus. This equates to up to 15 percent more thrust at high outside temperatures, which enables the new Harrier to return to an aircraft carrier without dropping unused weapons. Together with the reduced maintenance costs, this means greatly reduced overall costs for the drive.

This latest version of Pegasus was introduced in the further improved AV-8B-Harrier II +. This combines the proven advantages of day and night STOVL operations with a likewise new, advanced radar . The replacement of the MK.105 by Mk.107 engines is carried out by the RAF as part of the modernization of its Harrier GR7 fleet to the standard GR9. These aircraft are known as GR7As and GR9As.

Individual evidence

• Sir Stanley Hooker: Not Much of an Engineer. Airlife Publishing, ISBN 0-906393-35-3 .
• Rolls-Royce manufacturer's website

Web links

Commons : Rolls-Royce Pegasus  - collection of pictures, videos and audio files

• Harrier.org.uk Variants of the Pegasus (English)