The de Havilland Gyron Junior was a military turbojet engine 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.

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 th ...

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 The Bristol 188 is a British supersonic research aircraft built by the Bristol Aeroplane Company in the 1950s. Its length, slender cross-section and intended purpose led to its being nicknamed the "Flaming Pencil".

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 ...

but the half ton lighter Gyron Junior was substituted in June 1957. This engine was one of the first in the world to have infinite variation of thrust right up to full reheat; other manufacturers increased thrust in discrete steps. The program 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

, 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

* Blackburn Buccaneer S.1 : 40 aircraft built *

: Only 2 built *

Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster na ...

: 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 expe ...

: 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, England. The collection is built around the definitive prototype and restoration shops fo ...

London Colney London Colney () is a village and civil parish in Hertfordshire, England. It is located to the north of London, close to Junction 22 of the M25 motorway. It is near St Albans and part of the St Albans District. At the time of the 2001 census ...

Hertfordshire Hertfordshire ( or ; often abbreviated Herts) is one of the home counties in southern England. It borders Bedfordshire and Cambridgeshire to the north, Essex to the east, Greater London to the south, and Buckinghamshire to the west. For gov ...

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

East Midlands Aeropark East Midlands Airport is an international airport in the East Midlands of England, close to Castle Donington in northwestern Leicestershire, between Loughborough (), Derby () and Nottingham (); Leicester is () to the south and Lincoln () no ...

. 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 northwest of London Gatwick Airport in West Sussex, close west of Horley and north of Crawley. The historic county boundary between Surre ...

Surrey Surrey () is a ceremonial county, ceremonial and non-metropolitan county, non-metropolitan counties of England, county in South East England, bordering Greater London to the south west. Surrey has a large rural area, and several significant ur ...

, 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