The Supermarine B.12/36 was a British prototype four-engine heavy bomber design that was destroyed by enemy action before completion during the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

Design and development

In 1936 the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

issued specification B12/36, its first for a four-engined heavy bomber for the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

. Supermarine, among others, were invited to tender a design. Supermarine's design, the Type 316, was a single-spar, mid-wing aircraft; the leading edge was swept back but the trailing edge was straight. Bombs were carried in both the wings and the fuselage and defensive armament was in three turrets. Of the different powerplants suggested for the Type 316, there were three of more than 1,000 hp (746 kW): the

Rolls-Royce Merlin The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litres (1,650 cu in) capacity. Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was late ...

, the Bristol Hercules radial engine and the

Napier Dagger The Napier Dagger was a 24-cylinder H-pattern ''(or H-Block)'' air-cooled engine designed by Frank Halford and built by Napier before World War II. It was a development of the earlier Napier Rapier. Design and development The H-Block has a ...

. The aircraft's estimated maximum speed was between and the estimated cruising speed was . The estimated operating ceiling was around and range was . The different proposals were considered by the Air Ministry in late 1936. The 316 was initially low down in the list of preferred designs behind Vickers,

Boulton Paul Boulton Paul Aircraft Ltd was a British aircraft manufacturer that was incorporated in 1934, although its origins in aircraft manufacturing began earlier in 1914, and lasted until 1961. The company mainly built and modified aircraft under co ...

and Armstrong Whitworth but by January 1937 it had been selected as the preferred choice. Both the Air Ministry and Supermarine initiated changes to the design, giving it a larger wing area and a twin tail unit. This revised design was the Type 317 and two prototypes with Hercules engines were ordered on 22 March 1937. The Short S.29 was considered as a backup but re-design work was requested and in June the Air Ministry decided to order prototypes of that also. The death of the 316's chief designer R. J. Mitchell had made the Supermarine design riskier. To offer the greater use of possible engines, Supermarine continued with design work for a Merlin engined version – the Type 318. In July 1937 Supermarine were told to stop work on the 318 to concentrate on the 317. While still under construction, the two prototypes and the construction plans were effectively lost when the Supermarine Works at

Woolston Woolston may refer to: Places United Kingdom * Woolston, Cheshire, a village and civil parish in Warrington * Woolston, Devon, on the list of United Kingdom locations: Woof-Wy near Kingsbridge, Devon * Woolston, Southampton, a city suburb in Ham ...

was bombed by the ''

Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...

'' on 26 September 1940. The Air Ministry formally cancelled the order in November. The Short S.29 was accepted into service as the Short Stirling and was the principal British four-engine heavy bomber until eclipsed by the

Handley Page Halifax The Handley Page Halifax is a British Royal Air Force (RAF) four-engined heavy bomber of the Second World War. It was developed by Handley Page to the same specification as the contemporary twin-engine Avro Manchester. The Halifax has its orig ...

and Avro Lancaster, both coming out of specification B13/36 for a twin-engined bomber.

Notes and references

RJ Mitchell. A life in aviation
accessed 13 March 2008 * Buttler, Tony ''British Secret Projects: Fighters & Bombers 1935-1950'' Midland Publishing.

External links

{{DEFAULTSORT:Supermarine B.12 36 1930s British bomber aircraft B.12 36 Mid-wing aircraft