Supermarine Types 312 and 327

This design – Type 327 – was originally submitted as a tender to F.18/37 with 12 Brownings. 6 were mounted in each wing outboard of the nacelles. It was rejected as not offering any performance advantage over the Tornado/Typhoon that would justify using two Merlins, although it did get to mockup stage.

It was later, speculatively submitted as cannon fighter under Supermarine Spec. 460 dated 26/8/38. The 3-view posted by Mark 12 is from this Spec Document (i.e of the later, cannon armed version). The main changes were that 6 Hispanos were now mounted in the wing roots and the wing mounted airbrakes of the original version were deleted. The cannon were drum fed, but with the drums mounted somewhat remotely from the cannon, ammunition being fed from one to the other via duct made from some unspecified “flexible” material.

Basic Data for the cannon , Merlin powered version were given by Supermarine as:
Span: 40 ft
Gross wing area: 304 Sq ft
Length 33.5 ft
Fuel capacity 170 gallons
AUW: 11312 lbs (8769 lbs Tare)
Max Speed 465 at 22k and 423 at 15k
Service Ceiling 40k
Take off (zero wind) was given as 409 yds

Performance with optionanal Taurus power was slightly lower.

This design was also not much liked for much the same reasons, but with the additional one that the armament installation was seen as being impractical. There were also concerns about Supermarines ability to get it into production in a reasonable timeframe.

Type 327 shares some design features with the (earlier) Whirlwind: leading edge radiators (which may have looked pretty, but were almost certainly less aerodynamically effective than well designed conventional ones), full width Fowler flap and even the routing of the exhaust pipes through the nacelles to exit at the tail of the nacelle in the oil cooler outlet duct.

Type 327 is a very different beast to the Type 312 which was Supermarine’s tender to the F.37/35 Spec which led ultimately to the Whirlwind. 312 was Peregrine-powered twin and with a tailwheel undercarriage. (Supermarine also submitted a cannon-armed Sptfire) A prototype of the Type 312 (L6593) was ordered but later cancelled to allow Supermarine to concentrate on productionising the Spitfire and designing the B.12/36 Heavy Bomber for which the Supermarine Type 316-418 were seen as the most promising contenders (rather than the Stirling which ultimately won te production order)

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