{{short description|1950s British turboprop aircraft engine}} {{For|the 1920s piston engine|Bristol Jupiter}} {{Use dmy dates|date=September 2019}} <!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. --> {{infobox aero engine |name=Orion |image=Bristol Orion RRHT Derby.jpg |caption=Bristol Orion on display at the Rolls-Royce Heritage Trust, Derby |engine_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.<ref name=Kay>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</ref> 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.<ref>Gunston 1989, p.35.</ref>
The Orion gas generator had been chosen by French aircraft designer Wibault to power a vectored thrust aircraft<ref>Pegasus The Heart of the Harrier, Andrew Dow, Pen & Sword Aviation 2009, {{ISBN|978 1 84884 042 3}}, p.71/73</ref> 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.<ref name=Kay/>
==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 ({{Inflation|UK|4,750,000|1958|r=0|fmt=eq}}).<ref name="Flight, 17 August 1967, Cancelled projects list" >{{cite journal |journal=Flight |title=Cancelled projects: the list up-dated |chapter= |url=http://www.flightglobal.com/pdfarchive/view/1967/1967%20-%201672.html |date=17 August 1967 |pages=262 |ref=Flight, Flight, 17 August 1967, Cancelled projects list }}</ref>
==Applications== *Bristol Britannia *Canadair CL-44
==Specifications (BOn.1 Orion)== {{jetspecs <!-- If you do not understand how to use this template, please ask at Wikipedia talk:WikiProject Aircraft --> <!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). For additional lines, end your alt units with )</li> and start a new, fully-formatted line with <li> --> |ref=''Flightglobal archive''.<ref>[http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201242.html Flightglobal archive, 1956.] Retrieved: 31 December 2008</ref> |type=Twin-spool turboprop |length={{cvt|112.3|in}} |diameter={{cvt|41.8|in}} |weight={{cvt|3240|lb}} |compressor=7-stage LP axial flow compressor; 5-stage HP axial flow compressor |combustion=Cannular combustor with 10 flame tubes |turbine=Single-stage HP turbine, 3-stage LP turbine |fueltype=Kerosene / JP-1 |oilsystem=3 independent systems at {{cvt|80|psi}} |power=Take-off {{cvt|5150|shp}} (equivalent horsepower) |thrust= |compression=10:1 |aircon={{cvt|82|lb/s|kg/s}} |turbinetemp= |fuelcon= |specfuelcon={{cvt|0.39|lb/hp/h}} (equivalent horsepower) |power/weight= |thrust/weight={{cvt|1.63|hp/lb|kW/kg}} (equivalent horsepower) }}
==See also== {{aircontent <!-- other related articles that have not already linked: --> |see also= <!-- designs which were developed into or from this aircraft: --> |related= *Bristol Proteus <!-- aircraft that are of similar role, era, and capability this design: --> |similar aircraft= <!-- relevant lists that this aircraft appears in: --> |lists= *List of aircraft engines <!-- For aircraft engine articles. Engines that are of similar to this design: --> |similar engines= *Rolls-Royce Tyne <!-- See WP:Air/PC for more explanation of these fields. --> }}
==References== {{reflist}}
==Further reading== {{Commons category}} * {{cite journal |title=British Aero Engines 1956 |journal=Flight and Aircraft Engineer |date=31 August 1956 |volume=70 |issue=2484 |pages=383–393 |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201237.html |accessdate=16 March 2019}} * {{cite book |last=Gunston |first=Bill |title=World Encyclopaedia of Aero Engines |year=1989 |publisher=Patrick Stephens Limited |location=Cambridge, England |isbn=978-1-85260-163-8 |edition=2nd}} * {{cite journal |last1=Hooker |first1=Stanley, Dr. |url=https://www.flightglobal.com/pdfarchive/view/1955/1955%20-%200545.html |title=THE SUPERCHARGED TURBOPROP Dr. Hooker's S.A.E. Lecture on the Bristol B.E. 25, Successor to the Proteus |journal=Flight and Aircraft Engineer |date=29 April 1955 |volume=67 |issue=2414 |pages=545–547 |accessdate=16 March 2019}} * {{cite journal |title=ORION First Details of Bristol's New Turboprop |journal=Flight and Aircraft Engineer |date=26 October 1956 |volume=70 |issue=2492 |pages=677–682 |url=http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201521.html |accessdate=16 March 2019}} * {{cite book |last=Wilkinson |first=Paul H. |title=Aircraft engines of the World 1957 |year=1957 |publisher=Sir Isaac Pitman & Sons Ltd. |location=London |edition=15th |pages=134–135}} <!--==External links==--> {{Bristol aeroengines}}
Category:1950s turboprop engines Orion