Bristol Orpheus
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The Bristol Siddeley Orpheus is a single-spool
turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
developed by
Bristol Siddeley Bristol Siddeley Engines Ltd (BSEL) was a British aero engine manufacturer. The company was formed in 1959 by a merger of Bristol Aero-Engines Limited and Armstrong Siddeley Motors Limited. In 1961 the company was expanded by the purchase of t ...
for various
light fighter A light fighter or lightweight fighter is a fighter aircraft towards the low end of the practical range of weight, cost, and complexity over which fighters are fielded. The light or lightweight fighter retains carefully selected competitive fea ...
/trainer applications such as the
Folland Gnat The Folland Gnat is a British compact swept-wing subsonic aircraft, subsonic fighter aircraft that was developed and produced by Folland Aircraft. Envisioned as an affordable light fighter in contrast to the rising cost and size of typical comb ...
and the
Fiat G.91 The Fiat G.91 is a jet fighter aircraft designed and built by the Italian aircraft manufacturer Fiat Aviazione, which later merged into Aeritalia. The G.91 has its origins in the NATO-organised NBMR-1 competition started in 1953, which sough ...
. Later, the Orpheus formed the core of the first
Bristol Pegasus The Bristol Pegasus is a British nine-cylinder, single-row, air-cooled radial engine, radial aircraft engine, aero engine. Designed by Roy Fedden of the Bristol Aeroplane Company, it was used to power both civil and military aircraft of the 1 ...
vectored thrust
turbofan A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the add ...
used in the Harrier family.


Design and development

The engine had its genesis in a 1952 request by Teddy Petter of Folland for an engine in the 5,000  pounds (22  kN) class to power a new trainer and lightweight fighter-bomber they were developing.
Stanley Hooker Sir Stanley George Hooker, CBE, FRS, DPhil, BSc, FRAeS, MIMechE, FAAAS (30 September 1907 – 24 May 1984), was an English mathematician and jet engine engineer. He was employed first at Rolls-Royce where he worked on the earliest design ...
, relatively new to the company after an earlier career at
Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...
, took the project under his wing. He delivered a relatively simple and easy to maintain engine, which was put into use in the
Folland Gnat The Folland Gnat is a British compact swept-wing subsonic aircraft, subsonic fighter aircraft that was developed and produced by Folland Aircraft. Envisioned as an affordable light fighter in contrast to the rising cost and size of typical comb ...
, flying in 1955. The Orpheus incorporated the novel feature of a large-diameter shaft for its single spool which then needed only two bearings. The weight savings from deleting a bearing and associated parts listed below gave an engine with a thrust of 5,000 lbf but weighing only 800 lb. Eliminating the usual centre support bearing for the shaft joining the compressor and turbine meant the shaft would whirl, assuming a bowed shape, and damage the engine. Whirling was prevented by using a large diameter tube in place of the usual small diameter shaft. The large-diameter thin-walled tube, more than 8 inches in diameter was stiff enough to raise the whirling speed beyond the engine running range using only two bearings instead of the usual three. Two bearings gave a further advantage: previous engines had also needed a coupling in the shaft to allow for any misalignment between the static parts of the three bearings. With two bearings, the shaft simply followed the straight line between them. So the introduction of the large diameter tube allowed the removal of a bearing, a coupling, the engine's support structure for that bearing together with its lubrication system and cooling air supply. A cannular combustor was used with seven flame tubes. This was a recent development in jet engines and the Orpheus also included the innovation of incorporating the turbine entry duct and its stator vanes into the flame tube outlet, each flame tube providing one seventh of the overall duct. This had two advantages, it simplified the manufacture of a complicated and unreliable component, also the segmented design allowed easier allowance for thermal expansion. Developing a Sea Level Static thrust of , the Orpheus 701 had a 7-stage
axial compressor An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other ...
driven by a single stage turbine. In 1957
NATO The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...
ran a competition for a light fighter design. All three finalists chose the Bristol Orpheus and as a result a substantial contribution towards the cost of the initial engine development was made available from the
Mutual Weapons Development Program The Mutual Weapons Development Program was a NATO initiative established in Paris in 1954 as part of the alliance's efforts to enhance defense cooperation among member states. The program aimed to facilitate the exchange of weapons development data ...
. The winner of the competition, the
Fiat G.91 The Fiat G.91 is a jet fighter aircraft designed and built by the Italian aircraft manufacturer Fiat Aviazione, which later merged into Aeritalia. The G.91 has its origins in the NATO-organised NBMR-1 competition started in 1953, which sough ...
R and G.91T, used Fiat-built versions of the engine. Other users, mostly trainers, soon followed, including the
Fuji T-1 The Fuji T-1 Hatsutaka was Japan's first jet-powered trainer aircraft. Its first flight was in January 1958. A total of 66 T-1 planes were built.Simpson 2001, p.246 It was retired in March 2006. Design and development After World War II, Japan ...
, HAL HF-24 ''Marut'', HA-300, and the experimental Hunting H.126 and Short SB5. For later civilian applications, the Orpheus was chosen, after use of two each on the prototypes, as an option on the
Lockheed JetStar The Lockheed JetStar (company designations L-329 and L-1329; designated C-140 in US military service) is a business jet produced from the early 1960s to the 1970s. The JetStar was the first dedicated private jet to enter service, as well as the ...
, Lockheed's Vice President and head of the famous
Skunk Works Skunk Works is an official pseudonym for Lockheed Martin's Advanced Development Programs (ADP), formerly called Lockheed Advanced Development Projects. It is responsible for a number of aircraft designs, highly classified research and developme ...
, Clarence "Kelly" Johnson stating; "These Orpheus engines ... have been the best engines the writer has ever used in a prototype aircraft. They were and are so good that it was decided at an early date to make all Jetstars from serial number two up capable of using two Orpheus engines (as an alternative to four American units). The Orpheus version ... is fully competitive in performance (except with one engine out) and will be offered to those who want its lower cost, simplicity, and - at least for some time - reliability". Many companies in the 1950s were looking at ways of producing a vertical take off and landing aircraft.
Michel Wibault Michel Henri Marie Joseph Wibault (born 5 June 1897, died 23 January 1963) was a French aircraft designer. He was a strong advocate of metal construction, and his airliners were important in the development of French commercial aviation in the 1 ...
had the idea of using a
turboshaft engine A turboshaft engine is a form of gas turbine that is optimized to produce shaft horsepower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the ...
to drive four large centrifugal blowers which could be swivelled to vector the thrust. Hooker's engineers decided on using the Orpheus gas generator to drive a single large fan that would supply air to a pair of rotating nozzles, while the exhaust flow from the Orpheus was split into two and would supply another pair of nozzles at the rear of the engine. This experimental system developed into the Pegasus. Licences to produce the Orpheus were obtained by
Fiat S.p.A. Fiat S.p.A., or ''Fabbrica Italiana Automobili Torino'' (Italian Automobile Factory of Turin), was an Italian holding company whose original and core activities were in the automotive industry, and that was succeeded by Fiat Chrysler Automobil ...
,
SNECMA Safran Aircraft Engines, previously Snecma (''Société nationale d'études et de construction de moteurs d'aviation'') or Snecma Moteurs, is a French aerospace engine manufacturer headquartered in Courcouronnes and a subsidiary of Safran. It d ...
and - as the TJ37 -
Curtiss-Wright The Curtiss-Wright Corporation is an American manufacturer and services provider headquartered in Davidson, North Carolina, with factories and operations in and outside the United States. Created in 1929 from the consolidation (business), consoli ...
.


Variants

''Data from Jane's All the World's Aircraft 1962-63''., Aircraft engines of the World 1957 ;BOr.1:First run on 17 December 1954, rated at by Spring 1955, with for take-off later;powered the prototype
Folland Gnat The Folland Gnat is a British compact swept-wing subsonic aircraft, subsonic fighter aircraft that was developed and produced by Folland Aircraft. Envisioned as an affordable light fighter in contrast to the rising cost and size of typical comb ...
. ;BOr.2: for take-off ;BOr.3: for take-off ;BOr.4: for take-off (de-rated) ;BOr.6: ;BOr.11: Upflowed compressor enabled the BOr.11 to develop ;BOr.12: With a simplified reheat system the BOr.12 was rated at dry and with afterburning. ;Mk.100: Derated to ;Mk.101: ;Mk.701: Rated at , the Mk.701 was used in the production Folland Gnat F Mk.1 for
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
and
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
. ;Mk.703: Rated at ; powered the Hindustan HF-24 Marut Mk.1. ;Mk.703R: Reheated Mk.703 rated at powered the production version of the Hindustan HF-24 Marut. Reheat system developed by Hindustan Aeronautics Limited ;Mk.801: Rated at , powering G.91s. The Mk.801 was identical to the BOr.2 engine except for accessories. ;Mk.803: With improvements to the compressor, rated at , replaced earlier marks used in G.91s. ;Mk.805: de-rated to , powered Fuji T1F1 prototype and T-1A production aircraft, as well as the Hunting H.126 jet-flap research aircraft. ;FIAT 4023: Mk.803 engines Licence built by FIAT. ;FIAT 4023: Mk.803 engines Licence built by FIAT with added fire detection system.


Applications

;Aircraft * Armstrong Whitworth AW.171 * Breguet Taon *
Fiat G.91 The Fiat G.91 is a jet fighter aircraft designed and built by the Italian aircraft manufacturer Fiat Aviazione, which later merged into Aeritalia. The G.91 has its origins in the NATO-organised NBMR-1 competition started in 1953, which sough ...
*
Folland Gnat The Folland Gnat is a British compact swept-wing subsonic aircraft, subsonic fighter aircraft that was developed and produced by Folland Aircraft. Envisioned as an affordable light fighter in contrast to the rising cost and size of typical comb ...
*
Fuji T-1 The Fuji T-1 Hatsutaka was Japan's first jet-powered trainer aircraft. Its first flight was in January 1958. A total of 66 T-1 planes were built.Simpson 2001, p.246 It was retired in March 2006. Design and development After World War II, Japan ...
*
HAL HF-24 Marut The HAL HF-24 Marut ("Maruts, Spirit of the Tempest") is an Indian jet Fighter aircraft, fighter aircraft developed and manufactured by Hindustan Aeronautics Limited (HAL) during the 1960s and early 70s. The Marut was designed by the German ae ...
*Hawker P.1126 * Helwan HA-300 * Hunting H.126 * Short SB5 ;Other applications Orpheus engines, numbers 709 (destroyed by FOD in testing) and 711 (running) powered the
Bluebird K7 ''Bluebird K7'' is a jet engined Hydroplane (boat), hydroplane in which Britain's Donald Campbell set seven world water speed records between 1955 and 1967. ''K7'' was the first successful jet-powered hydroplane, and was considered revoluti ...
hydroplane in which
Donald Campbell Donald Malcolm Campbell, (23 March 1921 – 4 January 1967) was a British speed record breaker who broke eight absolute world speed records on water and on land in the 1950s and 1960s. He remains the only person to set both world land a ...
was killed whilst attempting the
water speed record The world unlimited water speed record is the officially recognised fastest speed achieved by a water-borne vehicle, irrespective of propulsion method. The current unlimited record is , achieved by Australian Ken Warby in the ''Spirit of Austra ...
on
Lake Coniston Lake Coniston (21 February 1991 – 29 May 2014) was an Irish-bred, British-trained Thoroughbred racehorse and sire (horse), sire. After being sold as a yearling (horse), yearling for 22,000 guinea (coin), guineas he was sent to be trained in E ...
in 1967. A dragster powered by an Orpheus, the "Vampire", is the current holder of the British land speed record.


Engines on display

Preserved Bristol Siddeley Orpheus engines are on display at
Aerospace Bristol Aerospace Bristol is an aerospace museum at Filton, to the north of Bristol, England. The project is run by the Bristol Aero Collection Trust and houses a varied collection of exhibits, including Concorde ''Alpha Foxtrot'', the final Concorde ...
, at the
Midland Air Museum The Midland Air Museum (MAM) is situated just outside the village of Baginton in Warwickshire, England, and is adjacent to Coventry Airport. The museum includes the ''Sir Frank Whittle Jet Heritage Centre'' (named after the local aviation pi ...
,
Coventry Coventry ( or rarely ) is a City status in the United Kingdom, cathedral city and metropolitan borough in the West Midlands (county), West Midlands county, in England, on the River Sherbourne. Coventry had been a large settlement for centurie ...
, and at
Solent Sky Solent Sky (previously known as the Southampton Hall of Aviation) is an aviation museum in Southampton, England. The museum depicts the history of aviation in Southampton, the Solent area and Hampshire. There is a focus on Supermarine, the air ...
,
Southampton Southampton is a port City status in the United Kingdom, city and unitary authority in Hampshire, England. It is located approximately southwest of London, west of Portsmouth, and southeast of Salisbury. Southampton had a population of 253, ...
. One is also preserved as a relic in India's first aerospace museum in Hindustan Aerospace Heritage Centre,
Bangalore Bengaluru, also known as Bangalore (List of renamed places in India#Karnataka, its official name until 1 November 2014), is the Capital city, capital and largest city of the southern States and union territories of India, Indian state of Kar ...
.


Specifications (Orpheus BOr.3 / Mk.803)


See also


Notes


References


External links


Flight Global online archive - Detailed description of the Orpheus, November 1957.


a 1959 ''Flight'' article {{Bristol aeroengines 1950s turbojet engines
Orpheus In Greek mythology, Orpheus (; , classical pronunciation: ) was a Thracians, Thracian bard, legendary musician and prophet. He was also a renowned Ancient Greek poetry, poet and, according to legend, travelled with Jason and the Argonauts in se ...