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The Hawker Hornbill was a fighter aircraft designed in 1925-26 that combined impressive performance figures with an awkward cockpit design that contributed to its failure to enter production. The Hornbill was designed in response to Air Ministry Specification 4/24, and the first version of the aircraft was designed by George Carter. The aircraft had to be built around the Rolls-Royce Condor III inline engine, and it would be this engine that gave the original Hornbill its distinctive feature. The Condor engine was an inverted 'V' inline engine, and Carter designed a streamlined cowling that fitted tightly around the 'V', with a central gully between the two rows of cylinders. The Hornbill was a single bay biplane with streamlined 'V' struts between the wings. The pilot was placed just below a cut-out section in the trailing edge of the upper wing. The original Hornbill made its maiden flight in July 1925, and went to Martlesham Heath to be assessed in December (at this stage it was unarmed, as the Condor III was not designed to be used with synchronisation gear). The aircraft's performance was good, but it tended to over-cool, risking damage to the engine.
In February 1926 the Hornbill was returned to Hawker for modifications. At this stage Carter was replaced by Sydney Camm. Under Camm the Condor III was replaced with a Condor IV. The split engine cowling was smoothed out and given a flat top to replace the gully. The original wing radiators were replaced with a semi-circular radiator placed under the fuselage. The aircraft was then returned to Brooklands for trials, still without a gun.
After making an appearance at the RAF Display at Hendon in July 1926 the modified Hornbill returned to Martlesham Heath for a full service assessment and comparative tests against the Armstrong Whitworth Siskin IIIA. The Hornbill was faster up to 21,000ft, but its performance fell off badly above that altitude, and its service ceiling was much lower than that of the Siskin. The well streamlined engine cowling and forward fuselage meant that the cockpit was too small - a normal sized pilot would be unable to reach the cocking handling of the Vickers gun, and a large pilot would be unable to bail out. The aircraft was also too directionally unstable. The aircraft was not judged suitable for military service. The single Hornbill prototype was purchased for the RAE, where it was used in experiments with automatic wing slats, and remained on charge until February 1932 (and in use until May 1933).
Engine: Rolls-Royce Condor IV
Power: 698hp
Crew: 1
Wing span: 31ft 0in
Length: 26ft 7 1/4in
Height: 9ft 8in
Empty Weight: 2,975lb
Loaded Weight: 3,769lb
Overload Weight: 3,820lb
Max Speed: 187mph at sea level
Cruising Speed: 140mph
Service Ceiling: 22,700ft
Range: 200 miles
Armament: One fixed forward firing Vickers Mk 2 gun