page_title: Rolls-Royce Pegasus
section_title: Nozzles
hierarchical_section_title: Rolls-Royce Pegasus / Design / Nozzles
caption_attribution_description: Deutsch: Das Triebwerk Rolls-Royce Pegasus im Deutschen Museum in München.
context_page_description: The Rolls-Royce Pegasus, formerly the Bristol Siddeley Pegasus, is a turbofan engine originally designed by Bristol Siddeley. It was manufactured by Rolls-Royce plc. The engine is not only able to power a jet aircraft forward, but also to direct thrust downwards via swivelling nozzles. Lightly loaded aircraft equipped with this engine can manoeuvre like a helicopter. In particular, they can perform vertical takeoffs and landings. In US service, the engine is designated F402.
  The unique Pegasus engine powers all versions of the Harrier family of multi-role military aircraft. Rolls-Royce licensed Pratt & Whitney to build the Pegasus for US built versions. However Pratt & Whitney never completed any engines, with all new build being manufactured by Rolls-Royce in Bristol, England. The Pegasus was also the planned engine for a number of aircraft projects, among which were the prototypes of the German Dornier Do 31 VSTOL military transport project.
context_section_description: The front two nozzles, which are made of steel, are fed with air from the LP compressor, the rear nozzles, which are of Nimonic with hot (650 °C) jet exhaust. The airflow split is about 60/40 front back. It is critical that the nozzles rotate together. This is achieved by using a pair of air motors fed from the HP (high pressure) compressor, in a fail over configuration, pairs of nozzles connected with  motorcycle chains. The nozzles rotate over an angular range of 98.5 degrees.
  The Pegasus was also the first turbofan engine to have the initial compressor fan, the zero stage, ahead of the front bearing. This eliminated radial struts and the icing hazard they represent.
caption: Exhaust nozzle
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