Bristol Orion

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The Bristol Orion aeroengine was a 2 shaft turboprop intended for later marks of the Bristol Britannia and Canadair CL-44.

A single stage HP turbine drove a 5 stage all-axial HP compressor, whilst a 3 stage LP turbine drove both the 7 stage LP compressor and the propeller, via a reduction gearbox. The combustor was cannular.

The Orion had a shared load LP turbine (like the Rolls-Royce Tyne), whereas its predecessor, the Bristol Proteus, had a free-power turbine.

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 all the way up to 15,000 ft altitude.

Although the engine was built and underwent a development programme, around 1959 the project was cancelled by the British Ministry of Supply. At that time, 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.