page_title: Rolls-Royce/Snecma Olympus 593
section_title: Exhaust nozzle
hierarchical_section_title: Rolls-Royce/Snecma Olympus 593 / Propulsion system design / Exhaust nozzle
context_page_description: The Rolls-Royce/Snecma Olympus 593 was an Anglo-French afterburning turbojet which powered the supersonic airliner Concorde. It was initially a joint project between Bristol Siddeley Engines Limited and Snecma. It was based on the Bristol Siddeley Olympus 22R engine. Rolls-Royce Limited acquired BSEL in 1966 during development of the engine making BSEL the Bristol Engine Division of Rolls-Royce.
  Until regular commercial flights by Concorde ceased, the Olympus turbojet was unique in aviation as the only afterburning turbojet powering a commercial aircraft.
  The overall thermal efficiency of the engine in supersonic cruising flight was about 43%, which at the time was the highest figure recorded for any normal thermodynamic machine.
context_section_description: The variable geometry exhaust nozzle, developed by SNECMA, consisted of two "eyelids" which varied their position in the exhaust flow dependent on the flight regime, for example when fully closed (into the exhaust flow) they acted as thrust reversers, aiding deceleration from landing to taxi speed.
  In the fully open cruise position, together with engine nozzle, they formed an ejector nozzle to control the expansion of the exhaust. The eyelids formed the divergent passage while the engine exhaust ejected or pumped the secondary flow from the intake ramp bleed slot.
  The expanding flow in the diverging section caused a forward thrust force on the exhaust nozzle, its 29% contribution to the overall propulsion system thrust at cruise.
  During cruise at Mach 2.05 each Olympus 593 was producing around 10,000 lbf of thrust, equivalent to 36,000 horsepower (~27 MW) per engine.
  The primary exhaust nozzle and jet pipe were designed for a life of 30,000 hours. The TRA (Thrust Reverser Aft) structure for a life of 40,000 hours.
caption: Concorde's variable geometry exhaust nozzle
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