spitfire Mk XII question

[hacker]

Ok reading up on the Mk XII it was first based on the Mk V airframe then later on the Mk VII. Now the Mk V it been said in everything l read that it was modified to take the Griffin engine. Now besides the obvious new nose my question is did they develop a new engine bearer and firewall or did they just use the existing ones that came with the Mk V?

Also is there any pictures of this installation?

[Test Graham]

Despite incorect assumptions based on the appearance of the tail, all Mk.XIIs were neither Mk.Vs nor Mk.VIIIs but Mk.XIIs, with differences from both. Yes, the Griffon required a new engine bearer to take the additional length, weight and power, so everything forward of the front tank frame was new. The main fuselage was also new in structural detail, possibly (I'm not sure here) having the introduction of flush rivetting. The wings were Mk.Vc, as modified for the Griffon cooling. Some of the tails were as fitted to Mk.V and others as to Mk.VIII, but the latter was actually known to Supermarine as the Mk.XII tail: it is just that they were more familiar to writers on Mk.VIIIs when the time came to publish the type.

[Edgar]

The engine bearers, for the XII, were identical (apart from the overall length) to those of the XIV:-

There's a general misconception that because a serial no. is in a sequence of a particular Mark, it means that it started life as said Mark, and was converted; well, it ain't necessarily so. In contract B19713/39, there was an order (the 7th.) for 500 Vc, which were eventually built as P.R.IV, VI, VII, IX, XI & XII, of which EN221-238/601-637 comprised the XII. The 10th order, for 426 Vc, was eventually built as VII, VIII, IX, X, XI, & XII, of which MB794-805/829-863/875-882 comprised the XII.

When flush rivetting was introduced, the XII was specifically included.

Edgar

[Andrew Jones]

The wings were Mk.Vc, as modified for the Griffon cooling.

I have read that the radiator and oil cooler specified for the Mk XII were the "MkV tropical types ", if this was the case, would the wings need modifying ?.

[Test Graham]

I think I've seen that said too, but was uncertain. I do not know what was done in detail, but am sure that the Griffon would have required more cooling than the Merlin 45. If the tropicalised version of the system was sufficient then a redesign would certainly have been avoided, yes.

[Edgar]

The radiator had the same frontal area as the tropical V, so, presumably, had the slightly bulged housing; the oil cooler was the same as the standard II & V.

Edgar