de Havilland Gyron Junior

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Gyron Junior
de Havilland Gyron Junior at the de Havilland Aircraft Heritage Centre
Type Turbojet
Manufacturer de Havilland Engine Company
First run August 1955[1]
Major applications Blackburn Buccaneer
Bristol 188
Number built 89
Developed from de Havilland Gyron

The de Havilland Gyron Junior was a military turbojet engine design of the 1950s developed by the de Havilland Engine Company and later produced by Bristol Siddeley. The Gyron Junior was a scaled-down derivative of the de Havilland Gyron.

Design and development[edit]

The Gyron Junior was a two-fifths output scaling down of the Gyron, starting as Project Study number 43 in 1954; the first prototype Junior ran in August 1955.[2]

Only a little more widely used than the Gyron, it did at least enter serial production for the Blackburn Buccaneer S.1 twin-engined Naval strike aircraft. However it was never a successful engine in service. The Buccaneer S.1 was criticised for being underpowered and the later and more numerous S.2 used the more powerful Rolls-Royce Spey instead.

Twin Gyron Juniors, with afterburners, were also used to power the Bristol 188 Mach 2 supersonic research aircraft. The Rolls-Royce Avon had been considered, but only the Gyron Junior was used in practice. The program was a disappointment, if not a failure, and was terminated early without achieving all of the high-speed high-temperature trials that had been intended. The limitation was the poor fuel consumption of the Gyron Junior and surging from the intakes. This could have been solved with Avons and the successful English Electric Lightning intake design, but the Avro 730 project that the 188 was a research aircraft for had been dropped as a result of the 1957 Defence White Paper which cancelled many manned aircraft designs under development as they were expected to be rendered obsolete by guided missiles. Only Mach 1.95 was achieved for a few minutes, endurance at any speed was so restricted by fuel limits that it was impossible to study the long-term "thermal soaking" of a supersonic airframe, as intended.



Gyron Junior DGJ.1
(or P.S.43)
Gyron Junior DGJ.2
Interim production stage, used on Buccaneer S. Mk.1.[3] Variable inlet and guide vane, annular manifold for flap blowing, 121 in (3.1 m) long overall
Gyron Junior DGJ.10
Exhibited in 1958 at Farnborough, longer than the DJG.1[4]
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 191 in (4.9 m)[5]
Gyron Junior DGJ.20


40 aircraft built[6]
Only 2 built
Testing only, 1 production FAW Mk.1 modified[7]
Intended application, not built

Engines on display[edit]

A de Havilland Gyron Junior is on display at the de Havilland Aircraft Heritage Centre, London Colney, Hertfordshire.

Also on display at the Gatwick Aviation Museum, Charlwood, Surrey, two running engines can also be found here, fitted to Buccaneer S.1, XN923.[8]

Specifications (Gyron Junior DGJ.10)[edit]

Data from Gunston.[1] Jane's All the World's Aircraft 1962-63[3]

General characteristics

  • Type: Single-spool after-burning turbojet
  • Length: 102.9 in (2.61 m)
  • Diameter: 41.1 in (1.04 m)
  • Dry weight:


  • Compressor: 7-stage axial flow with Variable Inlet GuideVanes (VIGV)
  • Combustors: Annular compustion chamber with 13 spill-type burners
  • Turbine: Two-stage axial flow
  • Fuel type: Aviation kerosene
  • Oil system: Pressure spray/splash with scavenging


  • Maximum thrust: 10,000 lbf (44.48 kN) dry, 14,000 lbf (62.28 kN) wet at sea level, 20,000 lbf (88.96 kN)+ at M2.5+ at 36,000 ft (10,972.8 m)
  • Overall pressure ratio: (DGJ.1)6.4:1[1]
  • Air mass flow: (DGJ.1)12.3 lb (5.6 kg)/sec[1]
  • Turbine inlet temperature: (DGJ.1)1,200 °C (2,190 °F)[1]
  • Power-to-weight ratio:

See also[edit]

Related development
Comparable engines
Related lists


  1. ^ a b c d e f Gunston, Bill (1989). World Encyclopaedia of Aero Engines. Wellingborough: Patrick Stephens. p. 52. ISBN 1-85260-163-9. 
  2. ^ Flight "Aeroengines 1960"
  3. ^ a b c d Taylor, John W.R. FRHistS. ARAeS (1962). Jane's All the World's Aircraft 1962-63. London: Sampson, Low, Marston & Co Ltd. 
  4. ^ "A New Gyron Junior" (PDF), Flight, August 1958 
  5. ^ "Aeroengines 1960", Flight, 18 March 1960 
  6. ^ Jackson, A.J. (1968). Blackburn Aircraft since 1909. London: Putnam Publishing. p. 494. ISBN 0-370-00053-6. 
  7. ^ James, Derek N. (1971). Gloster Aircraft since 1917. London: Putnam Publishing. pp. 322, 326, 370. ISBN 0-370-00084-6. 
  8. ^ Gatwick Aviation Museum - Buccaneer S.1 Retrieved: 23 February 2012

External links[edit]