"Which Wartime Spitfires Mounted 4 X 20mm Cannon?" Topic

My usual go-to sources have all failed me, so I appeal to the resident experts: Which wartime models of the Spitfire mounted 4 X 20mm cannon, and what success and history did this armament rig have?

I know that post-war, the wing of the Spitfire XIX was re-designed to mount 4 X 20mm, and other post-war Spitfire marks featured this rig, but I'm asking specifically about wartime Spitfires.

I know that the Spitfire prototype was originally designed to mount 4, later 8 X .30 MG, and this became the classic Battle of Britain Spitfire I. I know that during the BoB, RAF pilots demanded 20mm cannon to match the Bf-109, and so the Spitfire IB was designed, with 1 X 20mm and 2 X .30 MG in each wing. Spitfires with the 8 X .30 MG armament were re-designated Spitfire IA, and this A = 8 X .30 MG vs. B = 2 X 20mm + 4 X .30 MG nomenclature was continued through the Spitfire II, Spitfire V and later wartime marks.

It was difficult to fit even one 20mm cannon into the thin, delicate Spitfire wing. The engineers had to cover the cannon breech with a blister in the Spitfire IB. It doesn't look like a second 20mm could possibly fit. The wing blisters and the long cannon tubes made for easy visual identification of B model vs. A model Spitfires in all marks.

One set of sources tells me that a 'C' wing was designed for the Spitfire V, capable of mounting either the A or B weaponry. Did the C wing carry the blister as a standard feature, regardless of the weapons mounted? (I have some white metal Spitfire models showing the wing blisters but no gun tubes. Is this a bug or a feature?)

I'm told that maintenance crews sometimes stripped part of the armament from Spitfire Vs, to reduce weight and boost performance, and some pilots preferred the lighter-armed planes, with just 2 X 20mm or just 4 X .30 MG. I believe that story, unless you tell me it wasn't so.

What puzzles me is drawings I see (never photos) of Spitfire Vs with, clearly, 4 X 20mm cannon, two in each wing. Some of the drawings show an over-size wing blister covering the breeches of two cannon. All of the drawings show subjects in the Mediterranean theater, mostly Malta Spitfires. The planes are identified as Spitfire VCs.

What gives? Wasn't a Spitfire nC a Spit with the 'universal' C wing? Was there an officially designed manufactured and designated C model Spitfire that mounted 4 X 20mm? Was this a field expedient? Was it successful? Was it continued through later wartime Spitfire marks, especially the VII and the IX?

I'm aware of the Spitfire IXE variant with 2 X 20mm and 2 X .50 MG, one of each in each wing, built to USAAF requirements. I understand that version. Please explain to me about the 4 X 20mm cannon.

Do tell.

I hope this helps…

"In October 1941 the Mk Vc appeared. This used the universal "c" wing developed for the Mk III, which could carry either eight machine guns, four 20mm cannon or two cannon and four machine guns. The two cannon/ four machine gun combination was most common, as the four cannon version was significantly heavier, reducing performance."

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Spot on – the Vc was a V with the universal wing, on which the blister was standard (the point of the wing was that it could accommodate all standard weapon fits, so it was bulged to cater for the 20mm breaches, regardless of what armament actually went in – you could fit all Brownings [although the drawings I've seen only indicate bays for 2 on each wing – I don't think an 8-gun .303 armament was possible], all 20mm, or the usual 4 Brownings and 2 cannon, without needing to change the wing.) The bulge on each wing did have space for both cannon – the trick is that they were staggered, so the feed for the inboard cannon is in front of the feed for the outboard one, not alongside it.

This had the capacity to be fitted with 4x 20mm, (ie. what would be a "C" armament in Hurricane parlance) but the weight was usually deemed excessive, and 2x 20mm and 4x .303 was the usual fit, meaning the Vb and Vc *normally* had the same armament, just in different wings. The Vc had more ammo though (120 rpg for the 20mm vs 60 in the Vb) and the capacity was there to fit the 4x 20mm if desired, although it was pretty rarely utilised. One of the surviving airworthy Spits is actually a Vc flown in the 4 cannon configuration.

Dom.

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PS – The Malta depictions for 4-gun Spitfire Vc are correct but briefly so – HMS Eagle delivered a batch in that configuration, but they seem to have quite quickly had the outboard 20s stripped out and Brownings added for a "b" configuration.

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I found this useful:
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Thank you gentlemen. My mind is at rest. I can identify all the little lead Spitfires I have in my inventory and have a painting binge planned.

I don't have the reference to hand, but one of the South African squadrons was noted as unusually favouring four Hispanos on their Vcs in Italy in 43-44. Off the top of the head think it was either 2 SAAF or 4 SAAF Sqn.

As Dom says, the aircraft flown off Eagle to Malta were fitted with four Hispanos, but were rerigged on arrival for the two Hispano and four Browning configuration. The explanation I have seen is that it was the easiest way to establish an initial stockpile of Hispano spares on the island.