10 Foot Diameter Turrets?
 

To pass the time while dutifully locked down I’ve been re-reading the Putnam book The British Bomber Since 1914. In discussing the B.1/39 specification which eventually led to the Halifax, it quotes one of the requirements as four Hispano 20mm cannon in dorsal and ventral turrets, with a turret weight of 1,460 lb and a diameter not exceeding 10 feet.



A spot of Googling suggests that a gunner and a loader in each turret was planned, but a 10 foot diameter turret seems a bit unlikely to me. Four 20mms firing at a beam attack might have given the pilot a bit of a problem too. Any thoughts?

Just think of the weight of the ammunition too. How heavy is a single 20mm cannon shell? Four cannon in each turret, there would be nothing left for a bomb load.

Forget the weight, drag and C of G were bigger concerns. C of G being the reason I believe it was a non starter.

Pre-dated by the Boulton Paul P.92, which only ever flew as a half-scale prototype, but which was designed to meet the F.11/37 specification for a turret armed fighter aircraft. As designed the turret itself was a shallow dome, 13 ft in diameter, built into a thickened centre wing section and mounting four 20 mm cannon. The contract for the two full-scale prototypes was cancelled in May 1940, but the half-scale prototype that was ordered in May 1939 was completed and flew in early 1941. Wikipedia notes that while specification F.11/37 was suspended, the idea of a four cannon turret was relevant to B.1/39.

Looking at the photo on Wiki, it could do well in the "ugliest aircraft" category.