Spitfire Mk III

According to wiki, the Spitfire Mk III was not produced in order to allow for the Merlin XX to be used in the Hurricane Mk II. Is this true? Had the Spitfire III instead been chosen, what would the effects have been in 1940-1941? How would the Luftwaffe react to a 400+ mph Spitfire in late 1940 or early 1941? What effects would the lack of the Hurricane Mk II have, especially in subsidiary theatres?

I think the answer is in the question or is alluded to. Producing the MkIII would have given a better Spitfire but fewer of them and the Hurricane would have been completely outclassed elsewhere.

pbehn said:

I think the answer is in the question or is alluded to. Producing the MkIII would have given a better Spitfire but fewer of them and the Hurricane would have been completely outclassed elsewhere.

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Right, but was that assumption correct? What would it really have looked like?

Why not at least build a limited number of Mk IIIs while still building Hurricane Mk IIs? You could have 30% Spit Mk III, 70% Spit Mk V, 60% Hurricane Mk II, and 40% Hurricane Mk I. Send the old Hurricanes to North Africa and Asia where they could thump outdated Italian and Japanese aircraft while having a ferocious fighter force at home.

SpicyJuan11 said:

Right, but was that assumption correct? What would it really have looked like?

Why not at least build a limited number of Mk IIIs while still building Hurricane Mk IIs? You could have 30% Spit Mk III, 70% Spit Mk V, 60% Hurricane Mk II, and 40% Hurricane Mk I. Send the old Hurricanes to North Africa and Asia where they could thump outdated Italian and Japanese aircraft while having a ferocious fighter force at home.

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If you do that your 30% and 70% is of a much smaller number than just MkVs, they hadnt started with the MIII as a production model but had a lot of MkII fuselages already made. Making two types in one factory means less overall. The LW was already stating operations in N Africa and Malta as the issue was being discussed. To do as you suggest means having 4 types in production and 5 types in service

SpicyJuan11 said:

What would it really have looked like?

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Exactly the way it turned out.

The modifications that were the MkIII eventually became incorporated in some but not all late model Spitfires.

SpicyJuan11 said:

Right, but was that assumption correct? What would it really have looked like?

Why not at least build a limited number of Mk IIIs while still building Hurricane Mk IIs? You could have 30% Spit Mk III, 70% Spit Mk V, 60% Hurricane Mk II, and 40% Hurricane Mk I. Send the old Hurricanes to North Africa and Asia where they could thump outdated Italian and Japanese aircraft while having a ferocious fighter force at home.

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Japanese Zeros beat Mark V tropical Spitfires over Australia 28 Spitfires shot down to 4 Zeros lost after the Zeros flew 500 miles one way. Sending old Hurricanes to thump "outdated" japanese aircraft will only get lots of British pilots dead and make lots of Japanese aces

pinsog said:

Japanese Zeros beat Mark V tropical Spitfires over Australia 28 Spitfires shot down to 4 Zeros lost after the Zeros flew 500 miles one way. Sending old Hurricanes to thump "outdated" japanese aircraft will only get lots of British pilots dead and make lots of Japanese aces

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Sending aircraft to the other side of the world means that by the time they get there they are automatically one "generation" behind. Sending your replaced aircraft abroad means they are two generations behind.

SpicyJuan11 said:

Right, but was that assumption correct? What would it really have looked like?

Why not at least build a limited number of Mk IIIs while still building Hurricane Mk IIs? You could have 30% Spit Mk III, 70% Spit Mk V, 60% Hurricane Mk II, and 40% Hurricane Mk I. Send the old Hurricanes to North Africa and Asia where they could thump outdated Italian and Japanese aircraft while having a ferocious fighter force at home.

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The Spitfire III had many changes to the airframe, not just the engine, to tidy it up aerodynamically. The Spitfire II production would not be as rapid, or soon, as the Mk V.

I suppose a Mk V+ could have been built as an interim - a Mk V airframe (basically a Mk II airframe), adapted for the Merlin XX.

I am not sure that the resources were there for Supermarine to develop and build the Mk III and MK V at the same time.

pbehn said:

Sending aircraft to the other side of the world means that by the time they get there they are automatically one "generation" behind. Sending your replaced aircraft abroad means they are two generations behind.

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Any generation of Hurricane is inferior to a Zero. The Hurricane never bested the Zero or KI43 in any setting.

pinsog said:

Any generation of Hurricane is inferior to a Zero. The Hurricane never bested the Zero or KI43 in any setting.

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Oh I know, I was just speaking of a general principle.

The Spitfire V was supposed to be an interim, fitting the Merlin 45 to the Spit II fuselage and doing so meant more Spitfires as an expediency measure until something better coming along. Spitfire production was just branching out by the end of 1940 so as mentioned, putting the Merlin 45 into an existing airframe already on the production line was quicker than spending time developing the III. It's also worth noting that in late 1939 the first proposal for putting a Griffon into a Spitfire was put forward and a year later Supermarine wrote a letter to the Air Ministry stating that the Griffon engined Spitfire was going to be called the Mk. IV and in February 1941 a contract was offered to build one.

The Mk.III having been dropped in favour of putting those Mk.II airframes sitting on the production line to use was overtaken by events at any rate, as with the arrival of the Fw 190 scaring the RAF, although the Bf 109F proved itself superior to the Mk.V already, the decision to fit a 'High Altitude' 60 Series two-speed, two-stage supercharged Merlin to the Mk.V airframe as an interim produced the Mk.IX later in 1941, with plans to put the Mk.VIII into production as the next major Spitfire mark to be built. While all this was going on though, the Mk.IV was undergoing trials for production and a year later it was introduced as the first production Griffon engined Spitfire, the Mk. XII.

The Spitfire V was produced preferentially to the Spitfire III because the Mk III was not ready and the Bf 109 F, with far superior performance to the Spitfire I and II at high altitude, was already in service.

The engine used in the Mk V Spitfire was not a Merlin XX but the Merlin RM 5S, later designated Merlin 45, which was based on the Merlin XX but had the low altitude blower deleted to facilitate production. It was a Rolls Royce promise to supply 300 of these engines by 1 March 1941 (and another 200 by 1 April) without disrupting Merlin XX production which was a factor in the decision to abandon the Spitfire III and adopt the Spitfire V.

In a way what you proposed actually happened but later. Stonas post shows why they did what they did. Putting the XX in a Spitfire Mk III gets you a few Mk IIIs and a lot of poor Hurricanes.

When the two stage supercharger became available this was put in the MkIII prototype frame but again to maximise production the interim Mk IX was made. However they did produce lower numbers of the VII and VIII which were what the Mk III should have been, these were intended for use in the far east but at first went to Malta.

The Hurricane II and Spitfire V thing may have been set up before the 109F showed up.
The Hurricane I was having trouble with 109E so building more Hurricane I's through fall and winter of 1940 was not a recipe for success.
Late 109Es got DB601N engines which is going to increase difficulties for the Hurricane I's unless some sort of major improvement is done (Merlin XIIs probably won't cut it)

Shortround6 said:

The Hurricane II and Spitfire V thing may have been set up before the 109F showed up.
The Hurricane I was having trouble with 109E so building more Hurricane I's through fall and winter of 1940 was not a recipe for success.
Late 109Es got DB601N engines which is going to increase difficulties for the Hurricane I's unless some sort of major improvement is done (Merlin XIIs probably won't cut it)

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I am sure it did, even without any improvement in the 109 the Hurricane was down on performance, over Kent a Hurricane pilot knew as long as he didnt get shot down his adversary would eventually have to break off. Exactly the opposite on the other side of the Channel, but a Hurricane couldnt break off and get away.

A Hurricane could lose a Bf 109 on its tail in a slow tight turn. A Bf 109 couldn't follow through as at too tight a turn the Bf 109's slats on the uppermost wing would snap out. This tended to prevent the '109 from turning in tighter and spoiled the pilot's aim. The Hurricane was a superior close-in dogfighter to the '109, but, all things being equal, by the end of 1940 it was being left behind performance-wise by both homegrown and foreign fighters.

Shortround6 said:

The Hurricane II and Spitfire V thing may have been set up before the 109F showed up.

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There's a little bit of futzing of timelines in different sources I've looked at regarding this. According to Morgan and Shacklady in the Spitfire bible the decision to discontinue the Mk.III came about after the realisation that the new Messerschmitt that was being encountered had superior altitude performance to the Spit I and II and that the Merlin XX had a low altitude supercharger and was complex to produce, so the newer variant the RM 5S as mentioned earlier, the Merlin 45, which had better altitude performance to be installed in existing production airframes was the preferred option to counter the new aircraft.

Other books I've read offer the Bf 109F not being encountered by the RAF until March and April 1941, around which time it entered squadron service, which tends to support the theory that the Spit V decision had been made before the Bf 109F was first encountered... But... According to Radinger and Otto, a couple of the first production Bf 109F-1s were put into service for the purpose of evaluation in October 1940, well before the type entered squadron service, and saw combat, which might explain the encounters that Morgan and Shacklady mention.

Verney, the Director of Technical Development of the Air Ministry had a meeting in mid-November 1940 where he said the following: "one combat report suggested that the new Bf 109 could get to 38,000 feet when the Spitfire laboured to reach 36,500 feet [still higher than a P-39 a year later! My interjection ]." By the very end of December 1940, Sholto-Douglas had stated that he believed that the newer Merlin 45 should be reserved for Spitfire production over the Merlin XX, but it wasn't until following trials at Boscombe Down with a Spitfire Mk.I fitted with a Merlin 45 that the decision was made to cancel the Spitfire III and concentrate on the production of the newly designated Spitfire V that used existing airframes on the production line, rather than develop an entirely new variant.

Of course, as I mentioned earlier, there was a bit of development work going on in the background too, which meant that between the end of 1940 and the end of 1942 three distinct lines of Spitfire development were happening that kept the aircraft relevant throughout the rest of the war. These were, 1. the development of what was intended only as an interim in the Mk.V but eventually was numerically one of the most mass-produced variants of the Spitfire, 2. the developments of the different marks following the decision to fit the 60 Series Merlin to the type, and 3. the fitting of the Griffon to the airframe. With all this going on the Mk.III has been superseded by events.

nuuumannn said:

There's a little bit of futzing of timelines in different sources I've looked at regarding this. According to Morgan and Shacklady in the Spitfire bible the decision to discontinue the Mk.III came about after the realisation that the new Messerschmitt that was being encountered had superior altitude performance to the Spit I and II and that the Merlin XX had a low altitude supercharger and was complex to produce, so the newer variant the RM 5S as mentioned earlier, the Merlin 45, which had better altitude performance to be installed in existing production airframes was the preferred option to counter the new aircraft.

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The Merlin XX in FS gear had a slightly higher FTH than the 45 at the same boost.

The 45 had to compromise the FTH to avoid sacrificing too much lower altitude performance. The XX could have the FS gear FTH that little higher because it could use MS gear for lower altitude performance.

The V was the II with the Merlin 45. The III required much more modification, due to the longer Merlin XX plus several aerodynamic improvements - many of which made it into production with the Mk VII/VIII and Mk XIV.

wuzak said:

The V was the II with the Merlin 45. The III required much more modification, due to the longer Merlin XX plus several aerodynamic improvements - many of which made it into production with the Mk VII/VIII and Mk XIV.

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This I know, I've read the book. The first Vs off the production line were Mk.I airframes fitted with Merlin 45s. The entire progress of the Spitfire airframe through that crucial time period between the end of 1940 and end of 1942 was based on the progression of marks through existing airframes, the I and II airframes becoming the V, the V fitted with the 60 Series Merlin became the IX and features from the III in the VII and VIII fitted with the Merlin 60 series, with the VIII becoming the basis of the Griffon engined XIV, while the Mk.IV prototype became the Griffon engined Mk.XII prototype...