Orion
Bristol Orion on display at the Rolls-Royce Heritage Trust, Derby
Type Turboprop
Manufacturer Bristol Siddeley
First run 1956
Major applications Bristol Britannia

The Bristol Orion aero engine is a two-shaft turboprop intended for use in later marks of the Bristol Britannia and the Canadair CL-44. Although the engine was built and underwent a development program, the BE.25 Orion project was cancelled in 1958 by the British Ministry of Supply in favour of the Rolls-Royce Tyne.[1] In addition, interest in turboprop-powered aircraft was beginning to wane, because of the successful introduction of the Boeing 707 and Douglas DC-8 jetliners into airline service.[2]

The Orion gas generator had been chosen by French aircraft designer Wibault to power a vectored thrust aircraft[3] which ultimately became the Hawker Siddeley P.1127 but with a Bristol Siddeley Orpheus gas generator which had a compressor derived from the Orion low pressure compressor.[1]

Design and development

A single-stage HP turbine drove a five-stage all-axial HP compressor, while a three-stage LP turbine drove both the seven-stage LP compressor and the propeller, via a reduction gearbox. Thus the Orion used a shared-load LP turbine (like the Rolls-Royce Tyne), whereas its predecessor, the Bristol Proteus, had a free-power turbine. The combustor used separate flame cans.

One novel feature of the Orion was a derate from a thermodynamic rating of 9,000 shp at sea level, to enable a constant 5,150 ehp power level to be maintained up to 15,000 ft altitude.

The Orion project was cancelled in January 1958, at a reported total cost of £4.75 million (equivalent to $118,061,042 in 2021).[4]

Applications

Specifications (BOn.1 Orion)

Data from Flightglobal archive.[5]

General characteristics

  • Type: Twin-spool turboprop
  • Length: 112.3 in (2,850 mm)
  • Diameter: 41.8 in (1,060 mm)
  • Dry weight: 3,240 lb (1,470 kg)

Components

  • Compressor: 7-stage LP axial flow compressor ; 5-stage HP axial flow compressor
  • Combustors: Cannular combustor with 10 flame tubes
  • Turbine: Single-stage HP turbine, 3-stage LP turbine
  • Fuel type: Kerosene / JP-1
  • Oil system: 3 independent systems at 80 psi (550 kPa)

Performance

See also

Related development

Comparable engines

Related lists

References

  1. 1 2 Turbojet History And Development 1930-1960 - Volume 1 Great Britain and Germany, Antony L. Kay 2007, The Crowood Press Ltd., ISBN 978 1 86126 912 6, p.149
  2. Gunston 1989, p.35.
  3. Pegasus The Heart of the Harrier, Andrew Dow, Pen & Sword Aviation 2009, ISBN 978 1 84884 042 3, p.71/73
  4. "Cancelled projects: the list up-dated". Flight: 262. 17 August 1967.
  5. Flightglobal archive, 1956. Retrieved: 31 December 2008

Further reading

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