de Havilland Goblin

The de Havilland Goblin, originally designated as the Halford H-1, is an early turbojet engine designed by Frank Halford and built by de Havilland. The Goblin was the second British jet engine to fly, after the Power Jets W.1, and the first to pass a type test and receive a type certificate issued for an aircraft propulsion turbine.[1]

Goblin
Cutaway Goblin II
Type Turbojet
Manufacturer de Havilland Engine Company
First run 13 April 1942
Major applications de Havilland Vampire
Developed into de Havilland Ghost

Although it was conceived in 1941 it remained unchanged in basic form for 13 years by which time it had evolved to the Mk. 35 export version.[2]

The Goblin was the primary engine of the de Havilland Vampire, and was to have been the engine for the F-80 Shooting Star (as the Allis-Chalmers J36) before that design switched engines due to production delays at Allis-Chalmers. The Goblin also powered the Saab 21R, Fiat G.80 and de Havilland Swallow. The Goblin was later scaled up as the larger de Havilland Ghost, with the model numbers continuing from the last marks of the Goblin.

Design and development
de Havilland Goblin at RAF Museum Cosford

Design of the engine was carried out by Frank Halford at his London consulting firm starting in April 1941.[3] It was based on the overall design pattern pioneered by Frank Whittle, using a centrifugal compressor providing compressed air to sixteen individual combustion chambers, from which the exhaust powered a single-stage axial turbine.

Compared to Whittle designs, the H-1 was "cleaned up" in that it used a single-sided compressor with the inlet at the front, and a "straight through" layout with the combustion chambers exhausting straight onto the turbine. Whittle's designs such as the Power Jets W.2 used a "reverse flow" layout that piped the hot air back to the middle of the engine, in order to "fold" it and reduce its length and to reduce the turbine entry temperature, a safeguard necessary for the turbine materials available when Whittle was designing the engines.[4] Although it eliminated the Whittle-style "folding", the Goblin was still a very compact design.

The H-1 first ran on 13 April 1942 and quickly matured to produce its full design thrust within two months. It first flew on 5 March 1943 in the Gloster Meteor, and on 26 September in the de Havilland Vampire.[5] It was around this time that de Havilland purchased Halford's company and set him up as the chairman of the de Havilland Engine Company, with the engine name changing from H-1 to "Goblin", while the new H-2 design became the "Ghost" – de Havilland jet and rocket engines were all named after spectral apparitions.

In July 1943, one of the two H-1s then available (actually the spare engine intended as a backup for the one installed in the Vampire prototype) was sent to the United States, where it was selected to become the primary engine of the Lockheed P-80 Shooting Star. This engine was fitted to the prototype P-80, which first flew on 9 January 1944. The engine was later accidentally destroyed in ground testing, and was replaced by the only remaining H-1 from the prototype Vampire.[5] Allis-Chalmers was selected to produce the engine in the US as the J36, but ran into lengthy delays. Instead, the Allison J33, developed by General Electric as the I-40 (their greatly improved 4,000 lbf (18 kN) version of the J31, itself based on Whittle's W.1), was selected for the production P-80A.

Variants
A complete Goblin engine
H.1/Goblin I
Developed about 2,300 lbf (10.2 kN) thrust (nominal thrust for prototype) and 2,700 lbf (12.0 kN) for production models.
Goblin II (DGn.2)
3,100 lbf (13.8 kN)
Goblin 3 (DGn.3)
3,350 lbf (14.9 kN)
Goblin 35
3,500 lbf (15.6 kN)
Goblin 4 (DGn.4)
3,750 lbf (16.7 kN)
Allis-Chalmers J36
Licence production in the United States by Allis-Chalmers.
Svenska Flygmotor RM1
Goblin II production in Sweden
Svenska Flygmotor RM1A
Goblin III production in Sweden

Applications

Aircraft applications
The Goblin powered DH.108 Swallow

Alternative applications

Engines on display

Goblin engines are preserved and on display at several museums including:

Survivors

As of June 2011, two Goblin-powered de Havilland Vampires remain airworthy on the British register.[6]

As of December 2014, three Goblin-powered de Havilland Vampires remain airworthy in North America. N115DH is owned by the World Heritage Air Museum.,[7] C-FJRH is operated under the Jet Aircraft Museum in Ontario, Canada.[8] and N593RH is owned by Vampire Aviation LLC.

As of November 2015, three Goblin-powered de Havilland Vampires remain airworthy in South Africa. Serial number 276 and 277 are in the SA Air Force Museum and the third is at Wonderboom Airport.

Specifications (D.H Goblin II D.Gn 27)

Data from Smith[9][10]

General characteristics

  • Type: Turbojet
  • Length: 107 in (2,700 mm)
  • Diameter: 50 in (1,300 mm)
  • Dry weight: 1,550 lb (700 kg)

Components

Performance

See also

Related development

Related lists

References

Notes
  1. Gas Turbines and Jet Propulsion, G.Geoffrey Smith M.B.E., Revised and Enlarged By F.C. Sheffield, Sixth edition 1955, Iliffe & Sons Ltd. Dorset House, Stamford Street, London, S.E.1, p.220
  2. "Aero Engines 1954..." Flight. 9 April 1954. Retrieved 26 August 2017.
  3. Smith 1946, p.94.
  4. Note; the subsequent availability of a new turbine material, Nimonic, later made this "folding" unnecessary. The "straight through" design was also adopted by the Rover Company for its B.26 engine, later produced in modified form as the Rolls-Royce Derwent.
  5. Gunston 1989, p.51.
  6. G-INFO – UK CAA database Retrieved: 24 June 2011
  8. "Archived copy". Archived from the original on 31 December 2014. Retrieved 31 December 2014.CS1 maint: archived copy as title (link)
  9. Smith 1946, p.98.
  10. Wilkinson, Paul H. (1946). Aircraft Engines of the world 1946. London: Sir Isaac Pitman & Sons. pp. 286–287.

Bibliography
  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
  • Smith, Geoffrey G.Gas Turbines and Jet Propulsion for Aircraft, London S.E.1, Flight Publishing Co.Ltd., 1946.
  • Kay, Anthony L. (2007). Turbojet History and Development 1930–1960. 1 (1st ed.). Ramsbury: The Crowood Press. ISBN 978-1-86126-912-6.
  • Wilkinson, Paul H. (1946). Aircraft Engines of the world 1946. London: Sir Isaac Pitman & Sons. pp. 286–287.
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