Specification B.12/36 was issued by the British Air Ministry in 1936 to cover a new, all-modern, four-engined heavy bomber for use by the Royal Air Force (RAF). Three designs came from this initiative which was eventually fulfilled by the Short "Stirling" (detailed elsewhere on this site). The other two submissions were the ultimately-abandoned Armstrong Whitworth B.12/36 and the Supermarine B.12/36, the latter which produced the related Type 316, Type 317, and Type 318 forms.
Supermarine went down in World War 2 history as the makers of the classic "Spitfire" fighter series and added a navalized form through its "Seafire" development. However, large aircraft types were not out of its design, development and construction scope and proven by the many flying boats the company put out prior to the conflict. Against the details of their proposed "Type 316" to fulfill Specification B.12/36, Supermarine was contracted for two prototypes in 1937.
The Air Ministry sought a four-engined type with a maximum bomb load of 14,000lb and a range out to 2,000 miles. Conversely, engineers could opt for a longer-endurance design of 3,000 mile range with a reduced internal bomb load of 8,000lb. Cruising speeds would reach at least 230 miles per hour when flying at about 15,000 feet and turrets would be featured for local defense against enemy fighters. Beyond its service as a heavy bomber, the airframe should also prove suitable for service in the transport role. Drive power was also given some leeway for either Bristol (Hercules) or Rolls-Royce (Merlins) were under consideration for finalized bomber production forms. This produced the "Type 317" (Hercules-powered) and the "Type 318" (Merlin-powered) variants. In the end, the Merlin-powered variant was given up for good - no doubt those engines badly needed in other more important types like Spitfire fighters.
Nevertheless, work on the prototypes continued but it was in a September 1940 Luftwaffe air raid that the future of the Type 317 was settled - German bombs landed squarely on the production facility which rendered the still-incomplete bomber prototypes a total loss. After a quick status review, the program was cancelled in full during November of 1940, bringing about an end to the promising venture and heavier reliance on the Short Stirling and other heavy bomber types that would soon join the RAF inventory.
As finalized, the Type 317 carried a large-area monoplane wing with rounded, tapered tips. The mainplanes were seated ahead of midships. The cockpit was added in stepped fashion, overlooking the nose, with excellent views of each engine pair found along the wing leading edges. The engines were housed in streamlined nacelles for maximum aerodynamic efficiency. The nose was slightly glazed to provide vision for the bombardier and a nose-mounted gun position. The fuselage then tapered rearwards and another gun position was located at the extreme end of the tail. The tail unit itself comprised a horizontal plane unit with rudders affixed at the edges, completing a "twin rudder" appearance common to many aircraft of the period. The undercarriage was of a conventional "tail dragger" arrangement with the main legs double-tired.
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(OPERATORS list includes past, present, and future operators when applicable)
✓Ground Attack (Bombing, Strafing)
Ability to conduct aerial bombing of ground targets by way of (but not limited to) guns, bombs, missiles, rockets, and the like.
✓Transport
General transport functionality to move supplies/cargo or personnel (including wounded and VIP) over range.
✓X-Plane (Developmental, Prototype, Technology Demonstrator)
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.
Length
73.5 ft (22.40 m)
Width/Span
97.0 ft (29.57 m)
Height
22.0 ft (6.70 m)
Empty Wgt
38,581 lb (17,500 kg)
MTOW
59,007 lb (26,765 kg)
Wgt Diff
+20,426 lb (+9,265 kg)
(Showcased structural values pertain to the base Supermarine B.12/36 (Type 316) production variant)
Installed:
4 x Bristol Hercules HE 1.5M air-cooled radial piston engines developing 1,330 horsepower each.
(Showcased performance specifications pertain to the base Supermarine B.12/36 (Type 316) production variant. Performance specifications showcased above are subject to environmental factors as well as aircraft configuration. Estimates are made when Real Data not available. Compare this aircraft entry against any other in our database or View aircraft by powerplant type)
PROPOSED, DEFENSIVE (Never Fitted):
8 x 0.303in (7.7mm) machine guns in multiple defensive positions including the nose and tail sections.
PROPOSED OPTIONAL:
7 x 2,000lb conventional drop bombs (or similar) load.
Supported Types
(Not all ordnance types may be represented in the showcase above)
Hardpoint Mountings: 0
B.12/36 - Air Ministry Specification
Type 316 - Original proposed bomber form by Supermarine evolving to become the Type 317/Type 318 offerings.
Type 317 - Bristol Hercules-engined form eventually to serve as the production-quality model.
Type 318 - Rolls-Royce Merlin-engined form eventually dropped from consideration.
Ribbon graphics not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective aerial campaigns / operations / aviation periods.
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United Kingdom (cancelled)
