The de Havilland Gyron Junior is a military

turbojet engine 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 ...

design of the 1950s developed by the

de Havilland Engine Company The de Havilland Engine Company was an offshoot of the de Havilland aircraft building company, which started life as the 'Engine Division of the de Havilland Aircraft Company' in 1926 producing the famous de Havilland Gipsy aero-engine. The co ...

and later produced 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 ...

. The Gyron Junior was a scaled-down derivative of the

de Havilland Gyron The de Havilland PS.23 or PS.52 Gyron, originally the Halford H-4, was Frank Halford's last turbojet design while working for de Havilland. Intended to outpower any design then under construction, the Gyron was the most powerful engine of its ...

Design and development

The Gyron Junior was a two-fifths flow scale version of the existing Gyron engine. It started as Project Study number 43 in 1954 and the first prototype ran in August 1955. It powered the Blackburn Buccaneer S.1 twin-engined Naval strike aircraft. The engine was rather unreliable and considered short of thrust."A Passion For Flying"Tom Eeles, Pen & Sword Books Ltd. 2008, , p.42 The later Buccaneer S.2 used the more powerful

Rolls-Royce Spey The Rolls-Royce Spey (company designations RB.163 and RB.168 and RB.183) is a low-bypass turbofan engine originally designed and manufactured by Rolls-Royce that has been in widespread service for over 40 years. A co-development version of the ...

engine. The engine had variable inlet guide vanes, as used on many other engines, necessary for accelerating from idle to high thrust. However, on the Gyron Junior, positioning of the vanes was not reliable and could cause surging which, in turn, could prevent accelerating to higher thrust levels. A possibly unique feature on this engine was valve-controlled cooling air to the turbine blades. The engine had to supply air for the aircraft's boundary layer control system and the resulting thrust loss was unacceptable. To regain the thrust the turbine temperature limit was raised by using turbine blade cooling, selected only with blowing on. In December 1970 a Buccaneer was lost after one engine surged and failed to accelerate on an overshoot and a week later another aircraft was lost after an uncontained engine failure. This last accident brought to an end the use of Gyron Junior. Two Gyron Juniors, with afterburners, were also used on the Bristol 188 Mach 2 supersonic research aircraft. The 188 was originally intended to have the

Rolls-Royce Avon The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ai ...

but the half ton lighter Gyron Junior was substituted in June 1957. This engine was one of the first with continuously variable thrust up to full reheat; others increased thrust in discrete steps. The programme was terminated early without achieving the high-speed high-temperature trials that had been intended. Limitations included poor fuel consumption of the Gyron Junior and engine surging. Fuel limitations restricted the time spent at its maximum speed, Mach 1.95, to a few minutes. This was not long enough to achieve the required stabilized temperatures in "thermal soaking" tests.

Variants

''Ref:'' ;Gyron Junior DGJ.1: (or P.S.43) ;Gyron Junior DGJ.2: (Mk.101) Interim production stage, used on Buccaneer S. Mk.1. Variable inlet and guide vane, annular manifold for flap blowing, long overall ;Gyron Junior DGJ.10:Exhibited in 1958 at Farnborough, longer than the DJG.1 ;Gyron Junior DGJ.10R: (or P.S.50) highly augmented afterburning version for the Bristol 188, dry thrust 10,000 lb, wet thrust 14,000 lb (62.3 kN). Added zero stage and two rows of variable stators. Variable nozzle with convergent, convergent/parallel or convergent/divergent configuration depending on reheat selection and aircraft speed. Overall length ;Gyron Junior DGJ.20:

Applications

Avro 732 Avro (an initialism of the founder's name) was a British aircraft manufacturer. Its designs include the Avro 504, used as a trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the del ...

: Intended application, not built * Blackburn Buccaneer S.1 : 40 aircraft built * Bristol 188 : Only 2 built *

Gloster Javelin The Gloster Javelin is a twin-engined all-weather interceptor aircraft designed and produced by the Gloster Aircraft Company. It was operated by the Royal Air Force from the mid-1950s until the late 1960s and was the final aircraft design to b ...

: Testing only, 1 production FAW Mk.1 modified *

Saunders-Roe SR.177 The Saunders-Roe SR.177 was a 1950s project to develop a combined jet- and rocket-powered interceptor aircraft for the Royal Air Force (RAF) and Royal Navy. It was an enlarged derivative of the Saunders-Roe SR.53, which was itself an exper ...

: Intended application, not built

Engines on display

A de Havilland Gyron Junior is on display at the

de Havilland Aircraft Museum The de Havilland Aircraft Museum, formerly the de Havilland Aircraft Heritage Centre, is a volunteer-run aviation museum in London Colney, Hertfordshire, UK. The Museum's mission is to preserve and communicate the de Havilland Heritage to e ...

London Colney London Colney () is a village and civil parishes in England, civil parish in Hertfordshire, England. It is located to the north of London, close to Junction 22 of the M25 motorway. It is around south-east of St Albans city centre (and within ...

Hertfordshire Hertfordshire ( or ; often abbreviated Herts) is a ceremonial county in the East of England and one of the home counties. It borders Bedfordshire to the north-west, Cambridgeshire to the north-east, Essex to the east, Greater London to the ...

. A D.H Gyron Junior is on public display at

East Midlands Aeropark East Midlands Airport is an international airport in Castle Donington, England. The airport is situated between Loughborough (), Derby () and Nottingham (); Leicester is to the south and Lincoln northeast. It serves the majority of the East ...

. Also on display at the Gatwick Aviation Museum,

Charlwood Charlwood is a village and civil parish in the Mole Valley district of Surrey, England. It is immediately north-west of London Gatwick Airport in West Sussex, close west of Horley and north of Crawley. The historic county boundary between Sur ...

Surrey Surrey () is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Greater London to the northeast, Kent to the east, East Sussex, East and West Sussex to the south, and Hampshire and Berkshire to the wes ...

, two running engines can also be found here, fitted to Buccaneer S.1, ''XN923''.Gatwick Aviation Museum - Buccaneer S.1
Retrieved: 23 February 2012

Specifications (Gyron Junior DGJ.10)

References

External links

Photo of Gyron Junior

Gyron Junior on LeteckeMotory.cz
(cs) {{Bristol aeroengines Gyron Junior Bristol aircraft engines 1950s turbojet engines