| Orion | |
|---|---|
 Bristol Orion on display at theRolls-Royce Heritage Trust, Derby | |
| Type | Turboprop |
| Manufacturer | Bristol Siddeley |
| First run | 1956 |
| Major applications | Bristol Britannia |
TheBristol Orionaero engine is a two-shaft turboprop intended for use in later marks of theBristol Britannia and theCanadair CL-44. Although the engine was built and underwent a development program, the BE.25 Orion project was cancelled in 1958 by the BritishMinistry of Supply in favour of theRolls-Royce Tyne.[1] In addition, interest in turboprop-powered aircraft was beginning to wane, because of the successful introduction of theBoeing 707 andDouglas 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 theHawker Siddeley P.1127 but with aBristol Siddeley Orpheus gas generator which had a compressor derived from the Orion low pressure compressor.[1]
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 theRolls-Royce Tyne), whereas its predecessor, theBristol Proteus, had afree-power turbine. Thecombustor used separateflame cans.
One novel feature of the Orion was a derate from a thermodynamic rating of 9,000shp at sea level, to enable a constant 5,150ehp 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 $140,171,738 in 2023).[4]
Data fromFlightglobal archive.[5]
Related development
Comparable engines
Related lists
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