Authored By Dan Alex (Updated: 4/29/2015):
Origins of the Siskin can be traced back to the RAF Specification Type 1 requiring the development of a capable single-seat fighter to utilize the overly optimistic ABC Dragonfly radial piston engine of 320 horsepower - a product of ABC Motors Limited ("ABC" standing for "All-British engine Company"). The Dragonfly found its own origins as a product developed in the latter years of World War 1. The powerplant proved optimistic in that it promised to deliver excellent performance to push a new generation of fighters to all-new heights. Unfortunately, the Dragonfly proved quite unreliable and temperamental and performed at levels well below the advertised numbers. The engine was ultimately cancelled when all of its deficiencies could not be ironed out in whole.
The Siskin grew out of the Siddeley-Deasy S.R.2 Siskin aircraft designed by Major F.M. Green. Green served as chief engineer at the Royal Aircraft Factory and had now become a part of the Siddeley-Deasy Motor Car Company. Not limited to the production of motor vehicles, the Siddeley-Deasy brand also delved into manufacture of engines and aircraft. The company was based out of Coventry and was founded by Henry Hugh Peter Deasy. While Deasy left in 1908, J D Siddeley came aboard and changed the company name to Siddeley-Deasy. From there, the company would gradually morph into the Armstrong Whitworth Aircraft firm (known formally as the Sir W.G. Armstrong Whitworth Aircraft Co. Ltd after their 1920 merger with Armstrong Whitworth) and became responsible for a large portion of Siskin production thereafter.
The initial Siskin of all-wood construction flew with the ill-fated Dragonfly engine for the first time in May of 1919. The aircraft itself proved a capable mount though the engine left much to be desired. As a result, the Armstrong Siddeley Jaguar of 325 horsepower was selected to replace the Dragonfly in future flights of the Siskin. The new Siskin went airborne on March 20th, 1921.
By this time, the British Air Ministry had made a decision to pursue all-metal fighters for their future needs - the fear being that another war could spell shortages of wood and thusly affect the capability of wood-based fighter production in the UK. As such, the Siskin was redesigned in 1923 to incorporate an all-metal aluminum alloy internal frame. The new design was affixed the designation of Siskin III and flown on May 7th, 1923. The Royal Air Force (RAF) took notice and ordered six such systems for evaluation. Tests were conducted in January of 1924 and proved quite promising to the point that the Siskin III was officially accepted into service with the RAF. The Siskin became the RAFs first all-metal fighter and saw a first-run production total of 64 examples for RAF.
In all, the Siskin existed in only a handful of variants. There were the three Siddeley Deasy S.R.2 Siskin developmental aircraft which was followed two civilian Siskin II prototypes - the second becoming the prototype fighter model. The series took a change for the better with the arrival of the Siskin III, now an all-metal design, of which 64 were produced for the Royal Air Force.