De Havilland DH77
The sole example of the De Havilland DH77, showing the closely-cowled Napier engine and wide undercarriage track.
The De Havilland Aircraft Company DH77 was built to Air Ministry Specification F.20/27, which called for a single seat interceptor fighter of short-range with exceptional climb and manoeuvrability.
After 1926, De Havilland military prototype designs (including the DH77) were outsourced to W.G. Carter, Chief Designer at Gloster Aircraft Co Ltd  who had worked in very close collaboration with De Havilland engine designer, Major Frank Halford. This was a purely commercial decision as the time, the De Havilland Design Team were concentrating solely on civilian aircraft types.
Construction of the DH77 was initiated as a private venture, without any form of government or airline funding, and the light-weight prototype was designed around the novel Napier Rapier engine. This specification sought a 'short-range, fast-climbing interceptor', capable of high-altitude operation whilst carrying a minimum of equipment.
The Rapier light-weight engine was designed with four sets of cylinders arranged in an ‘H’ configuration and driving two crankshafts, geared together to provide final drive to the propeller. This arrangement resulted in minimum frontal area, albeit with an increase in complexity.
When tested, the DH77’s performance proved to be inferior to the heavier (and considerably more powerful) Hawker Hornet biplane, which offered a higher speed and a better rate of climb.
The DH77 was a diminutive aircraft by comparison and its empty weight was low at 1,655 lb, compared with the Hawker Hornet at 2,409 lb. Armament comprised two Vickers guns faired into the fuselage sides. Unusually for aircraft of this size and type, an all-moving tail-plane was fitted, designed to provide excellent control power and to ensure good spin recovery characteristics.
Despite its comparatively low-power, a clean maximum speed of 204 mph was achieved at 10,000ft, reducing to some 185 mph with a full military load.
The sole prototype was taken into RAF charge (as J9971) for test and evaluation and the first flight took place on 11th July 1929. 
The aircraft was further trialed at Martlesham Heath from 12th December 1929 before being delivered into service at The Royal Aircraft Establishment (RAE) at Farnborough on 8th December 1932, where it underwent additional testing. 
Eventually, it was returned to Martlesham Heath where sadly, it remained until June 1934.
The Hawker Hornet was selected for production and it entered RAF service as the Hawker Fury.


De Havilland DH77
A fine air to air photograph of the De Havilland DH77.



Powerplant One 301 hp Napier Rapier I 
Span 32 ft 2 in
Maximum Weight 2,279 lb
Capacity & Armament Pilot and two Vickers machine guns
Maximum Speed 203 mph at 10,000ft (unladen); 182 mph with full military load


Numbers Built

Number built                       Single prototype only J9971                                                             



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