Miles Master

The Miles M.9 Master was a British two-seat monoplane advanced trainer designed and built by aviation company Miles Aircraft Ltd. It was inducted in large numbers into both the Royal Air Force (RAF) and Fleet Air Arm (FAA) during the Second World War.

The Master can trace its origins back to the earlier M.9 Kestrel demonstrator aircraft. Following the failure of the rival de Havilland Don as a satisfactory trainer aircraft, the RAF ordered 500 M9A Master advancer trainers to meet its needs. Once in service, it provided a fast, strong and fully aerobatic aircraft that functioned as an excellent introduction to the high performance British fighter aircraft of the day: the Spitfire and Hurricane. Throughout its production life, thousands of aircraft and various variants of the Master were produced, the latter being largely influenced by engine availability. Numerous Masters were modified to enable their use as glider tows. The Master also served as the basis for the Miles Martinet, a dedicated target tug adopted by the RAF.

Perhaps the most radical use of the aircraft was the M.24 Master Fighter. Armed with six .303 in machine guns, it was intended to function as an emergency fighter during the Battle of Britain; this model did not ultimately see combat. Ordinary trainer models could also be fitted with armaments, including a single .303 in Vickers machine gun and eight bombs, albeit intended for training purposes only. Beyond the British air services, other nations also chose to adopt the Master, including the South African Air Force, United States Army Air Force (USAAF), Irish Air Corps, Royal Egyptian Air Force, Turkish Air Force, and the Portuguese Air Force. While thousands of Masters were manufactured, no complete examples have been preserved.

Background
The M.9A Master I was based on the M.9 Kestrel trainer that was first demonstrated at the Hendon Air show in July 1937, although this aircraft never entered production. The M.9 Kestrel, powered by a single Rolls-Royce Kestrel XVI V-12 engine, capable of generating up to 745 hp (555 kW), could attain a maximum speed of 296 mph (477 km/h). The British Air Ministry had previously selected the rival de Havilland Don to meet Specification T.6/36, which called for an advanced trainer aircraft; however, this aircraft would prove to be a failure. Still requiring an aircraft to perform the duties intended for the Don, the RAF placed a large order for 500 examples of a modified version of the Kestrel, designated M.9A Master, at a cost of £2 million.

Upon receipt of this order, Miles had the prototype M.9 rebuilt into a representative prototype for the Master. Alterations included the installation of a lower-powered (715 hp (535 kW)) Kestrel XXX engine, of which there were large surplus stocks available, along with extensive revisions to the airframe, which involved the adoption of a new cockpit canopy, a modified rear fuselage and tail, along with the repositioning of the radiator from underneath the nose to the underside of the wing's centre-section. These modifications came at the cost of a significantly reduced maximum speed over the M.9; despite this, the Master was a relatively fast and manoeuvrable trainer. According to aviation periodical Flight International, Miles had designed the Master to fulfil their vision of an effective trainer aircraft being one that could match the performance of, and possess similar characteristics to, that of the frontline RAF monoplane fighters of the day, these being the Supermarine Spitfire and the Hawker Hurricane.

Into flight
On 31 March 1939, the first true production Master I conducted its maiden flight. According to Flight, the first production examples were being delivered during late July of that year. The Master had entered RAF service just prior to the start of the Second World War Eventually, 900 Mk. I and Mk. IA Masters were constructed. This total included 26 built as the M.24 Master Fighter which were modified to a single-seat configuration, and armed with six .303 in machine guns for use as an emergency fighter; this model never saw any combat use.

When production of the Kestrel engine ceased, a new variant of the Master was designed that used an air-cooled Bristol Mercury XX radial engine, capable of producing 870 hp (650 kW), instead. Thus configured, on 30 October 1939, the first M.19 Master II prototype made its first flight; 1,748 aircraft were eventually built. After the Lend-Lease programme provided a supply of engines from the United States to Britain, a third variant of the Master, designated M.27 Master III, was designed, which was powered by the American-built Pratt & Whitney Twin Wasp Junior, a two-row radial engine that could generate 825 hp (615 kW). A total of 602 Master IIIs were constructed.

In a typical trainer configuration, the Master was equipped to carry eight practice bombs, plus a single .303 in Vickers machine gun that was mounted in the front fuselage. During 1942, it was decided to have the wings of all variants clipped by three feet (c. one metre); this modification reduced the stress imposed upon the wings while also increasing the aircraft's manoeuvrability.