I'm going to build a Spitfire PR Mk. ID (or PR IV). Was this mark equipped with the Mk. 1 early oill filter housing, or the filter housing from a Mk. V?
My references notes that the early marks of recce Spitfires often were reengined, but mentions nothing about the oilfilter. None of my pictures gets close enough to get a clear view of the oil filter housing.
I hope there's some Spitfire experts out there!
Knud Laugesen
That's a very good question. I have looked through "Spitfire: The History" by Eric Morgan and Edward Shacklady and "Classic Warbirds: Merlin PR Spitfires" by Wojtek Matusiak. While they have lots of photos of these aircraft, in every case the oil cooler is in shadow. I had hoped that the Morgan/Shacklady book would have some engineering drawings, but no such luck.
So... here's a bit of speculation.
The first two PR.IDs were hand built, converted from fighter Mk I aircraft. The first aircraft was P9551 which was delivered on 21 September 1940. P9552 was delivered on 26 February 1941. Both aircraft had Merlin III engines as fitted to the Mk I.
The production run were designated PR.IV. They had Merlin 40 series engines, as fitted to Mk Vs, even though the first aircraft were converted from Mk Is.
Therefore I would speculate that the first two, hand-built, aircraft had the same oil cooler as the Mk I. The production aircraft probably had the Mk V type cooler. It seems pointless fitting the more powerful Merlin 40 to an aircraft if you are going to hamper it by fitting a less efficient oil cooler.
I must stress that the above is *speculation* on my part. I don't have any evidence to support it.
The first two aircraft were never rebuilt to production standard. P9551 was shot down on 2 Feb 1941 while operating from Malta while P9552 failed to return from a mission on 10 May 1941.
All the articles I've ever seen on converting Spitfire MkI's into the PR aircraft have always made the point that the oil cooler was the MkV type. There was a company in the UK who made resin conversion sets about 15 years ago, I still have some and they've all got them. I also recall an article in an IPMS mag many years ago that made this claim.
HTH
Chris
All the references I can find say that the PR.IV had a Merlin 45/46, the same engines fitted to the Mk.V.
In "Spitfire Mk.V Aces 1941-45" (Alfred Price, Osprey), the author states that the first Mk.V's were converted from Mk.I's and II's but that it was found that the Merlin 45 ran hotter and needed a new larger oil cooler. The larger cooler, with its fully circular intake, was introduced as a change on the production line and also retrofitted to all earlier Mk.V aircraft. As all the PR.IV's were produced on the Mk.V line, it seems certain that they all received the larger cooler. It is just possible, I suppose, that some PR.IV's were produced before the modification was introduced, and flew for a while with the smaller cooler.
As you say, the PR.IV grew out of the Mk.ID, which had introduced a new wing (the "D" wing) with carriage of fuel in the leading edges, deleted guns and a 14 gallon oil tank in one of the port wing gunbays. This means it didn't have the deeper nose profile associated with some PR Spitfires, as this was an alternative location for the larger oil tank, and this was true for the PR.IV as well.
Well, three of three suggest the Mk. V filter om most PR mk. IV's, so I think I'll put one om my PR. Mk. IV.
I appreciate your help!
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