The Bristol Siddeley Orpheus was 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, an ...

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/trainer applications such as the

Folland Gnat The Folland Gnat is a British compact swept-wing 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 combat aircraft, it wa ...

and the

Fiat G.91 The Fiat G.91 is an Italian jet fighter aircraft designed and built by Fiat Aviazione, which later merged into Aeritalia. The G.91 has its origins in the NATO-organised NBMR-1 competition in 1953, which sought a light fighter-bomber (offici ...

. Later, the Orpheus formed the core of the first Bristol Pegasus vectored thrust

turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which achieves mechanic ...

used in the Harrier family.

Design and development

The engine had its genesis in a 1952 request by

Teddy Petter William Edward Willoughby "Teddy" Petter (8 August 1908, Highgate in Middlesex – 1 May 1968, Béruges) was a British aircraft designer. He is noted for Westland's wartime aeroplanes, the Canberra, the early design of the Lightning, and his la ...

Folland Folland is a surname. Notable people with the surname include: *Alison Folland (born 1978), American actress and filmmaker * Gerald Folland (born 1947), American mathematician * Henry Folland (1889–1954), British aviation engineer and aircraft de ...

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 a mathematician and jet engine engineer. He was employed first at Rolls-Royce where he worked on the earliest designs such as ...

, 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

, 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 A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion chamber is fed ...

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 driven by a single stage turbine. In 1957

NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...

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 Mutual may refer to: *Mutual organization, where as customers derive a right to profits and votes *Mutual information, the intersection of multiple information sets *Mutual insurance, where policyholders have certain "ownership" rights in the orga ...

. The winner of the competition, the

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 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, Japanese aircr ...

, HAL HF-24 ''Marut'',

HA-300 The Helwan HA-300 ( ar, حلوان ٣٠٠) was a single-engine, delta-wing, light supersonic interceptor aircraft developed in Egypt during the 1960s. At various stages, Spain and India were involved in the development program. Spain was fin ...

, and the experimental

Hunting H.126 The Hunting H.126 was an experimental aircraft designed and built by British aviation company Hunting Aircraft. The aircraft was developed in order to test the performance of blown flaps, which were commonly known in Britain as "jet flaps", At ...

and

Short SB5 The Short SB.5 ( serial ''WG768'') was a "highly unorthodox, adjustable wing"Staples K.J. British research aircraft designed by Short Brothers in response to the UK Air Ministry requirement ER.100; to provide input for the design of the Engl ...

. 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 business jet to enter service, as well as t ...

, 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, beginning with the P-38 Lightning in 1 ...

Clarence "Kelly" Johnson Clarence Leonard "Kelly" Johnson (February 27, 1910 – December 21, 1990) was an American aeronautical and systems engineer. He is recognized for his contributions to a series of important aircraft designs, most notably the Lockheed U-2 an ...

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 shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust ...

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.,

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 ...

and - as the TJ37 -

Curtiss-Wright The Curtiss-Wright Corporation is a 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 of Curtiss, Wright, and v ...

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

. ;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 ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

and

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. ;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 The HAL HF-24 Marut ("Spirit of the Tempest") was an Indian fighter-bomber aircraft of the 1960s. Developed by Hindustan Aeronautics Limited (HAL), with Kurt Tank as lead designer. The Project Engineer from HAL was George William Benjamin. It is ...

. 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

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 *

Breguet Taon Breguet or Bréguet may refer to: * Breguet (watch), watch manufacturer **Abraham-Louis Breguet (1747–1823), Swiss watchmaker **Louis-François-Clement Breguet (1804–1883), French physicist, watchmaker, electrical and telegraph work * Bréguet ...

* HAL HF-24 Marut *

Helwan HA-300 The Helwan HA-300 ( ar, حلوان ٣٠٠) was a single-engine, delta-wing, light supersonic interceptor aircraft developed in Egypt during the 1960s. At various stages, Spain and India were involved in the development program. Spain was fina ...

;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 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 revolutionary when launched i ...

hydroplane in which

Donald Campbell Donald is a masculine given name derived from the Gaelic name ''Dòmhnall''.. This comes from the Proto-Celtic *''Dumno-ualos'' ("world-ruler" or "world-wielder"). The final -''d'' in ''Donald'' is partly derived from a misinterpretation of the ...

was killed whilst attempting the water speed record on Lake Coniston in 1967. A dragster powered by an Orpheus, the "Vampire", is the current holder of the

British land speed record The British land speed record is the fastest land speed achieved by a vehicle in the United Kingdom, as opposed to one on water or in the air. It is standardised as the speed over a course of fixed length, averaged over two runs in opposite direc ...

Engines on display

Preserved Bristol Siddeley Orpheus engines are on display at Aerospace Bristol, 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 pionee ...

Coventry Coventry ( or ) is a city in the West Midlands, England. It is on the River Sherbourne. Coventry has been a large settlement for centuries, although it was not founded and given its city status until the Middle Ages. The city is governed b ...

, and at

Solent Sky Solent Sky is an aviation museum in Southampton, Hampshire, previously known as Southampton Hall of Aviation. It depicts the history of aviation in Southampton, the Solent area and Hampshire. There is special focus on the Supermarine aircraft c ...

Southampton Southampton () is a port city in the ceremonial county of Hampshire in southern England. It is located approximately south-west of London and west of Portsmouth. The city forms part of the South Hampshire built-up area, which also covers Po ...

. One is also preserved as a relic in India's first aerospace museum in Hindustan Aerospace Heritage Centre,

Bangalore Bangalore (), List of renamed places in India, officially Bengaluru (), is the Capital city, capital and largest city of the Indian state of Karnataka. It has a population of more than and a metropolitan area, metropolitan population of a ...

Specifications (Orpheus BOr.3 / Mk.803)

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 Orpheus (; Ancient Greek: Ὀρφεύς, classical pronunciation: ; french: Orphée) is a Thracian bard, legendary musician and prophet in ancient Greek religion. He was also a renowned poet and, according to the legend, travelled with J ...