09/30/2024. Remarks by
Johan Visschedijk: "A Specification for a reconnaissance aircraft issued by the British Air Ministry shortly after WW I, was declared unsatisfactory by designers of several manufacturers. A reissued Specification in 1921 was followed another one in 1922, this outlined satisfactory the general requirements for an aircraft capable of performing field operations, such as gunnery spotting, 'terrain surveillance' and unit liaison, generically termed Corps Reconnaissance Duties. For the H.G. Hawker Engineering Co. Ltd. at Kingston it resulted in an order for four prototypes.
The two-seat Corps Reconnaissance parasol monoplane design tendered by the Hawker Design Staff, under its newly appointed Chief Designer, Captain B. Thomson, was accepted and construction of a number of prototypes commenced at Hawker. Only one Duiker, as the machine was called, was completed after numerous alterations had been made to the basic configuration. Armament consisted of one Vickers gun on nose cowling and provision for one Lewis gun, however, the design loaded weight of 4,940 lb (2,241 kg) was considered unsafe during flight tests and 240 lb (109 kg) of equipment was deleted, including the armament. This aircraft, later registered J6918, was flown a number of times at Brooklands Aerodrome, Weybridge, Surry, during July 1923, by Fred P. Raynham.
(
Johan Visschedijk Collection)
The Duiker was of all-wood construction with fabric covering, featuring a swept-back parasol wing and was powered first by a 300 hp Armstrong Siddeley Jaguar fourteen-cylinder two-row air-cooled radial engine, and later by a 389 hp Bristol Jupiter IV nine-cylinder air-cooled radial engine, driving a two-blade wooden propeller. A feature of this first new aircraft built by the Hawker, was the relatively large number of proprietary items of equipment manufactured by Vickers Ltd - another occupant of Brooklands Aerodrome - for apart from the Vickers gun fitted on the nose, the wind-driven generator, undercarriage oleos with 39.37x5.91 in (1,000x150 mm wheels, stick and rudder controls, rear gun mounting and tail skid were all of Vickers' stock.
J6918 was delivered to Martlesham Heath for assessment late in 1923, but only eighteen hours flying proved sufficient to indicate that the Duiker was not suitable as a military aircraft. Apart from displaying severe aileron flutter (which resulted in a tendency for the wing to part company with the rear cabane struts) the aircraft was directionally unstable throughout the entire speed range; moreover, undamped pitching oscillations resulted when the throttle was closed. It is true that a metal wing, presumably intended to give greater torsional stiffness, was designed for the Duiker, but it was never completed.
J6918 was delivered to the RAE at Farnborough on April 15, 1924, but its fate is unknown. The other four Duikers that had been ordered, J6919, J6920, J6995 and J6996, were not completed."
