single ABC Dragonfly radial engine, which was installed on the nose in a streamlined cowling. To regulate the engine's temperature, each individual cylinder had its own cooling channel. Armament consisted of a pair of Vickers machine guns mounted directly in front of the pilot. The Siskin made its first flight in May 1919. While the initial aircraft was powered by the intended Dragonfly engine, it would only deliver rather than the expected . Despite early promise, the Dragonfly was disastrous, being less powerful, unreliable, and prone to overheating while excessive vibration resulted in crankshaft failures after only a few hours of use. Despite the engine, the Siskin displayed generally good properties, possessing favourable stability and handling characteristics, along with performance that could outmatch its direct rivals for RAF orders. Redesign In 1919, Siddeley-Deasy merged with Armstrong Whitworth, with the aviation interests becoming Armstrong Whitworth Aircraft. Siddeley-Deasy had inherited the design of the RAF 8 fourteen-cylinder radial engine and its designer Sam D. Heron. By 1920, this engine, as the Jaguar, had been developed sufficiently to replace the Dragonfly. A prototype Siskin fitted with a Jaguar flew on 20 March 1921. Air Ministry officials were impressed but urged Armstrong Whitworth to continue developing the aircraft as only an all-metal design would be acceptable to the Royal Air Force (RAF). During 1922, Air Ministry Specification 14/22 was issued for an all-metal single-seat high performance landplane. The Siskin was submitted leading to an order for a single Jaguar-powered prototype. Aside from the engine change, Major Green redesigned it with an all-metal structure, as the Siskin III. The all-metal Siskin was the start of the British transition to metal for military aircraft. Into production On 13 October 1922, an initial contract for three production aircraft was placed, and a follow-on order for a further six followed on 26 January 1923, including a single two-seat variant. The Siskin III made its first flight on 7 May 1923. A comprehensive evaluation was conducted, during which the ailerons were tapered to prevent them jamming, as happened during one test flight. Shortly thereafter, Armstrong Whitworth commenced construction of the production standard Siskin, the first of which were delivered to the Royal Air Force (RAF) in January 1924 for flight trials on No. 41 Squadron. The fighter was constructed with a composite wood and aluminium frame, covered in doped linen fabric. Following the orders from the RAF, Armstrong Whitworth