Learned colleagues. Looking at the recent restorations of both Spitfire P9374 and N3200 i have seen two very large bulges on the top of the engine cowlings above the exhausts. Can anyone tell me the reason for them as i have checked many period 1940 images of the same area and the bumps mentioned were tiny and more streamlined back then. [ATTACH=CONFIG]238480[/ATTACH]
By: One of the Few - 18th June 2015 at 20:14
That makes a lot of sense Edgar thank you. The larger compressor would be used today on a restoration hence a larger bulge than what would have been on a MkI fitted with a Merlin III in 1940.
By: Edgar Brooks - 18th June 2015 at 19:53
The position of that bulge matches where the compressor was fitted; on early Marks it was a “B.T.H. Type AV” (whatever that means,) which was quite small. According to Vickers, it was replaced by a “Heywood” compressor in March 1942, which, in a drawing, appears to jut up higher than the earlier type. On later Marks, this needed a fairing to allow cooling air around it. Maybe today’s compressor also needs extra space, hence the larger bulge.
The Coffman starter bulge was low down on the starboard engine cover, just behind the propeller.
By: Arabella-Cox - 18th June 2015 at 19:51
The blister covers the Heywood compressor.
The Coffman L4 starter is below the exhaust stubs on the right side. Cartridge breech is lower and adjacent to the rear of the engine. See fig.
DAI
By: One of the Few - 18th June 2015 at 18:59
Robert the period pictures from 1940 show the same smaller teardrop style covering on the MkI`s as well, so i wonder why the new recreations have such large and bulged coverings.
By: Robert Whitton - 18th June 2015 at 18:35
P9374 and N3200 are both 1a’s and as far as I am aware the 11’s has a teardrop to cover the coffman cartridge starter to replace the electric one. K9942 at Cosford is configured as an early Mk1 but has the same teardrop.
But hopefully the Spitfire experts will be along soon.
By: mike currill - 18th June 2015 at 17:56
An interesting question to which I would also like to know the answer. I imagine they cover some ancillary item or its associated drive.
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June 18, 2015 at 5:39 pm