Question for Spitfire Pros

[afspret]

This is a new pic on the NAVSOURCE website that states it was taken on the hanger deck of the USS Wasp (CV-7) on 3 May 1942.  What caught my eye is the additional bulges on top of the wings near the roundels of these three Spitfire Mk. VCs, which are in addition to the normal bulges over the gun bays.  I've never noticed them before on other pics of this mark and am wondering if they were particular to the marks armed with four 20mm cannons or just this particular batch.  

[Britaholic]

There was a thread on this subject over on Britmodeller and the late Edgar Brooks commented:

This has been exercising us for some time, and we simply don't know, for sure. I think it's to do with the gun heating, since the bulges are very close to where the ammunition feeds/breeches would be on the outermost guns. The intensifier tubes, which ran through the exhausts then to the Brownings, are listed as having been designed (under mod 420) for the IIb & Vb only. If it was thought that the Vc would need the same extra heating (and that seems extrememly logical and likely,) without the intensifier tubes the heat could only come from the radiator, having first to pass through the cannon bays. By the time it reached the last .303" it's possible that the supply pipework needed to be fairly wide, to ensure enough heat was delivered, to do the job. Fatter pipe = bulged wing, at least that's my theory, and that's all it is, since, so far, I've not been able to find anything that I can use with certainty.

Edgar

The other possible explanation voiced was that it was for a modified aileron actuator.

 

Here's a link https://www.britmodeller.com/forums/index.php?/topic/234967425-spitfire-mk-vc-wing-bulge-question/

 

Cheers

 

Dennis

[afspret]

Thanks, and cheers to you as well.