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Supermarine B.12/36 (Type 316)

United Kingdom (1937)
Picture of Supermarine B.12/36 (Type 316) Heavy Bomber Prototype

This Supermarine bomber project was, itself, ended by German bombs dropped on the production facility in September of 1940.


Detailing the development and operational history of the Supermarine B.12/36 (Type 316) Heavy Bomber Prototype.  Entry last updated on 8/16/2016. Authored by Staff Writer. Content ©www.MilitaryFactory.com

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.
By mid-August of 1937, Supermarine had delivered a mockup model for official review and the design was becoming promising enough to continue pursuit - particularly in light of foreign air powers finding considerable successes with their own four-engined heavy bomber types - up to this point the Royal Air Force held an affinity for less-complex bomber workhorses usually driven by a pair of engines. The death of lead engineer R.J. Mitchell (1895-1937) from cancer in June of 1937 proved a devastating setback for the program which still hoped to garner complete support from the Air Ministry going forward and Supermarine's preoccupation with Spitfire production only served to push the Type 317 program back even further.

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.

The Type 317 was designed to support a crew of six. Power was to be served from 4 x Bristol Hercules HE 1.5M series air-cooled radial piston engines developing 1,330 horsepower each. Dimensionally, the aircraft carried a wingspan of 97 feet and a length of 73.5 feet. Its service ceiling was estimated at 32,000 feet. Defensive armament amounted to 8 x 0.303in (7.7mm) machine guns located along various danger zones about the aircraft - at least two would be showcased at the nose and the tail. Internally, the bomb bay was cleared for carrying up to 7 x 2,000lb bombs or similar loads.






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed Rating
Hi: 400mph
Lo: 200mph
    This entry's maximum listed speed (329mph).

    Graph average of 300 miles-per-hour.
Relative Operational Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Supermarine B.12/36 (Type 316)'s operational range (on internal fuel) when compared to distances between major cities.
Aviation Era Impact
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Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
2
2


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
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Supported Mission Types:
Air-to-Air
Interception
Unmanned
Ground Attack
Close-Air Support
Training
Anti-Submarine
Anti-Ship
Airborne Early Warning
MEDEVAC
Electronic Warfare
Maritime/Navy
Aerial Tanker
Utility/Transport
Passenger Industry
VIP Travel
Business Travel
Search/Rescue
Recon/Scouting
Special Forces
X-Plane/Development
National Flag Graphic
National Origin: United Kingdom
Service Year: 1937
Classification Type: Heavy Bomber Prototype
Manufacturer(s): Supermarine - United Kingdom
Production Units: 2
Global Operators:
United Kingdom (cancelled)
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Supermarine B.12/36 (Type 316) model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
6


Dimension
LENGTH


Feet
73.49 ft


Meters
22.4 m


Dimension
WIDTH


Feet
97.01 ft


Meters
29.57 m


Dimension
HEIGHT


Feet
21.98 ft


Meters
6.7 m


Weight
EMPTY


Pounds
38,581 lb


Kilograms
17,500 kg


Weight
LOADED


Pounds
59,007 lb


Kilograms
26,765 kg

Installed Power - Standard Day Performance:
4 x Bristol Hercules HE 1.5M air-cooled radial piston engines developing 1,330 horsepower each.

Performance
SPEED


Miles-per-Hour
329 mph


Kilometers-per-Hour
530 kph


Knots
286 kts


Performance
RANGE


Miles
3,679 mi


Kilometers
5,920 km


Nautical Miles
3,197 nm


Performance
CEILING


Feet
31,972 ft


Meters
9,745 m


Miles
6.06 mi


Performance
CLIMB RATE


Feet-per-Minute
800 ft/min


Meters-per-Minute
244 m/min

Armament - Hardpoints (0):

PROPOSED, DEFENSIVE (Never Fitted):
8 x 0.303in (7.7mm) machine guns in multiple defensive positions including the nose and tail.

PROPOSED OPTIONAL:
7 x 2,000lb conventional drop bombs or similar load.
Visual Armory:

Graphical image of an aircraft medium machine gun
Graphical image of an aircraft conventional drop bomb munition
Variants: Series Model Variants
• 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.