Spitfire alternative history: what happens if everything "goes to plan"?

[pathology_doc]

As any deeply invested Spitfire fan knows, the intended major developments never eventuated and the history of the Spitfire was one of interim variants that did very well. The dead ends are as follows:
SPITFIRE III: Merlin 20 development with four cannon and major airframe revisions; abandoned.

SPITFIRE IV: First, single-stage Griffon variant, not proceeded with (first production Griffon Spits developed from Vc airframe). One-off re-designated Mark XX to free up Mark IV for PR variants.

SPITFIRE VIII: Non-pressurized, improved airframe arising from Mk VII; developed and served, but overshadowed in history and numbers by interim Mk IX.

SPITFIRE XXI/F.21: Redesigned wing for improved roll rate and aileron reversal speed for Griffon engine. Developed and served, but only very late and grossly overshadowed by interim Mk XIV.


Let's look at a timeline in which the Spitfire III progresses quickly to production and service. As I see it, the Griffon Spitfire has the potential to overshadow the III very quickly in performance terms, but will probably not be production-ready until the two-stage Merlin is ready to go. With the Griffon managing the low-altitude task well, the Merlin variants will be given engines scheduled more toward the high altitude bands and they will take care of this until a two-stage Griffon variant is ready to go. Thus:

My revised timeline:
Mk I, II - as OTL
Mk III - Production aircraft, possibly with LF variant with cropped two-speed Merlins giving best speeds around 5,000 and 15,000 ft.
Mk IV - Production single stage Griffon variant, essentially doing the job the XII does in the OTL but appearing somewhat sooner and appearing as a revised airframe rather than a bolt-on of the Vc.
Mk V - With the III in production and the OTL Mk V no longer necessary, this becomes the "dumping ground" mark for the PR variants.
Mk VI - Hypothesized Mk III, Merlin 20-something development with pressure cabin and supercharger speeds scheduled high (replaces VI in OTL).
Mk VII - Definitive HF Merlin variant with 60-series engine. The final variant might be the VII E or even an FR.VIIE with the .50 cal/20mm armament and a bubble canopy.
Mk VIII - Pressurized fighter variant of VII (replaces OTL Mk VII).
Mk IX - Pressurized PR variant of VIII (essentially doing what the PR.XI does in OTL).
Mk X - First two-stage Griffon variant, based on Mk VII (basically replacing the XIV in the OTL). See comment for Mk VII.
Mk XI - PR variant of X, most likely pressurized and in all likelihood identical to the OTL PR.XIX.

Here in my opinion the Revised Timeline development of the Spitfire stops. The original timeline's F.21, with the new wing and too many other changes, gets called the Supermarine Victor F.1 as IMHO it always should have done, and Supermarine gets to finish the war with a new fighter just making it into service before the conflict ends.

I have not attempted to deal with Seafire evolution, but I think it would follow similar lines to those seen IRL, since the Service favoured low-blown Merlins for maximum power near sea level. With Griffon Spitfires being introduced sooner than in the OTL, a switch to what eventually got called the Seafire XV would probably also come into service sooner. I find it interesting that the two-stage, two-speed Merlin variants never saw carrier service.

 

[Rule of cool]

I love the Mk VIII, IIUC it had significantly more fuel than the Mk IX of similar performance.

 

[Apophenia]

I love the Mk VIII, IIUC it had significantly more fuel than the Mk IX of similar performance.

Yes. According to the site quoted below, the Spitfire VIII carried 31 Imperial gallons more fuel that the Spitfire IX. This was the result of a five Imperial gallon increase in the main tanks and the addition of two small wing tanks with a total capacity of 27 Imperial gallons.

Spitfire VIII ... fuel capacity has been increased to 96 gallons in the main tank, with 27 gallons carried in the two wing tanks, making a total of 123 gallons.

-- http://www.spitfireperformance.com/spit8tac.html

The fuel capacity of the Spitfire IX is 92 gallons, 57 in the top tank and 35 in the bottom tank. This is 10 gallons more than the Spitfire VC.

-- http://www.spitfireperformance.com/spit9tactical.html

 

[tomo pauk]

SPITFIRE III: Merlin 20 development with four cannon and major airframe revisions; abandoned.

Aircraft revisions were minor: clipped wings (reverted to the normal wings on the 2nd prototype), and a bit re-hashed and strengthened front fuselage because of heavier engine and more fuel carried. Different weapon set-ups were discussed, including two belt-fed Hispanos, while one series of 1000 aircraft was supposed to carry the usual 8 .303 battery.

As for the alternative time line, I'd go like this:
Mk.I - as is
Mk.II - Merlin III with pressure injection carb, less draggy exhausts (as the Bf 109D and He 112B have gotten), some protection for pilot and fuel (we should hopefully get into 370+ mph range now), has drop tank facility (yes, this requires some doctrine shift in the AM and RAF)
Mk.III - as per historical aircraft + better carb + better exhausts = 390+ mph in service; drop tanks can be carried; Mk.IIIB has cannons
Mk.IV - same as Mk.III, but with Merlin 45
Both marks can have easlily removable 29 imp gal tank behind the pilot, as it was the case with historical Mk.Vs for overseas deployment. Some have the Merlin 46 or 47.
Mk.V - the 1st Griffon-powered version, the 29 imp gal tank is the fixed accesory; standard battery consists of two cannons and 4 .303s
Mk.VI - placeholder
Mk.VII - 2-stage Merlin with the LE tanks (internal fuel is now almost 150 imp gals, giving the footprint necessary for operations in the Med and Asia/Pacific)
Mk.IX - Spitfire III and IV re-engined with 2-stage Merlin engines, standard internal fuel is a bit shy of 130 gals
Mk.X - Griffon power, on what is basic Spitfire III airframe

... more later

 

[tomo pauk]

-- http://www.spitfireperformance.com/spit9tactical.html

Perhaps this Mk.IX was a prototype of some kind? 'Normal' fuel tankage of Spitfire IX was 85 (84?) gals - FWIW.

 

[Apophenia]

Perhaps this Mk.IX was a prototype of some kind? 'Normal' fuel tankage of Spitfire IX was 85 (84?) gals - FWIW.

Could be. It would also have been nice if Spitfire Performance had mentioned how that five gallon increase was achieved - ie: was it the upper or lower main tank that was changed?

 

[EwenS]

I have not attempted to deal with Seafire evolution, but I think it would follow similar lines to those seen IRL, since the Service favoured low-blown Merlins for maximum power near sea level. With Griffon Spitfires being introduced sooner than in the OTL, a switch to what eventually got called the Seafire XV would probably also come into service sooner. I find it interesting that the two-stage, two-speed Merlin variants never saw carrier service.

According to David Brown in "Seafire. The Spitfire that went to Sea"

"Adaptation of the two-stage Merlin 60-series engined Spitfires Mark IX or VIII was impractical because of foreseeable structural deficiencies which could not be overcome by strengthening which would further increase the weight of the aircraft."

So what became the Seafire XV became a combination of the basic Seafire III wings and fuselage, Spitfire XII engine installation (but naval version of the engine itself - Griffon VI), wing fuel tanks and tail (complete with retractable tailwheel and enlarged rudder) from the Mk.VIII. Numerous other changes were required, like changes to wing incidence, to tame it for the flight deck.

The Admiralty didn't need a high altitude aircraft as most of its air fighting in the first half of WW2 took place below 15,000ft. What it did need was a fast climbing interceptor for fleet defence which performed best at those heights. That was provided in the Griffon engined Seafire XV. The Firefly and US types like the Corsair & Hellcat would provide strike escort.

The Seafire XV was intended as the fleet interceptor for 1944 with a Spitfire XXI derivative intended for 1945. Development delays pushed all these plans back, with the Mk.XV only reaching the first front line squadron at the beginning of Aug 1945.

The Griffon VI also required its M-ratio supercharger clutch sorted out. It slipped causing problems on take off and landing. Between Aug 1946 and early 1947 Griffon engined Seafires were prohibited from flying from carrier decks because of this fault.

 

[Justo Miranda]

Some Mk. III info

 

[Justo Miranda]

Post-2

 

[Justo Miranda]

Post-3

 

[pathology_doc]

According to David Brown in "Seafire. The Spitfire that went to Sea"
(clipped)

Thanks for that background.

Some Mk. III info

I think I've either read or possibly even own the (English-language) books all this comes from, but thank you for condensing and summarizing it here.

 

[pathology_doc]

Justo, which book is 090.jpg from? I think it's one I've been looking for for a very long time and couldn't remember the title of. I'd read it ages ago in Manchester Public Library when I was visiting there, and of all the photocopies I took from it, the important one I forgot to take was the front cover.

 

[Justo Miranda]

Justo, which book is 090.jpg from? I think it's one I've been looking for for a very long time and couldn't remember the title of. I'd read it ages ago in Manchester Public Library when I was visiting there, and of all the photocopies I took from it, the important one I forgot to take was the front cover.

Images 087,088,089 and 090 were scanned from a very popular book about the Spitfire, but sadly I don't remember the title.

 

[pathology_doc]

but sadly I don't remember the title.

Dammit!

If anyone knows, post it here because I want to find myself a copy - for nostalgic reasons if nothing else. Those performance tables were so neatly laid out, and IIRC they incorporated data for rare marks such as the mysterious F.XIII!

 

[Rule of cool]

What would the combat outcomes be of the 'proper' types being used instead of the interims? Were there any battles involving the MkIX for example where the MkVIIIs extra 50% fuel would have provided a significant advantage?

 

[Justo Miranda]

What would the combat outcomes be of the 'proper' types being used instead of the interims? Were there any battles involving the MkIX for example where the MkVIIIs extra 50% fuel would have provided a significant advantage?

Schweinfurth

 

[Justo Miranda]

Dammit!

If anyone knows, post it here because I want to find myself a copy - for nostalgic reasons if nothing else. Those performance tables were so neatly laid out, and IIRC they incorporated data for rare marks such as the mysterious F.XIII!

I only borrow the best books (I can't buy them all) and then have the odd habit of returning them, I think it was one of two:



https://www.fleurfinebooks.com/product/17661/Spitfire

https://www.amazon.com/Spitfire-History-Eric-B-Morgan/dp/0946219486

 

[pathology_doc]

I think it was one of two

The book I read existed in 1995, so I don't think it was Flack's work if 1996 was the publishing date. I vaguely remember a blue cover.

I own the big Spitfire encyclopaedia and I'm pretty sure it's not that.

 

[Rule of cool]

Schweinfurth

The USAAF raids in 1943?

 

[Justo Miranda]

The USAAF raids in 1943?

If the Spitfires escorting the bombers had been able to penetrate further into the Reich's airspace to relieve the exhausted Thunderbolts that were running low on ammunition, many American battle damage bombers that were shot down by German fighters over France and Holland would have been able to return.

 

[tomo pauk]

What would the combat outcomes be of the 'proper' types being used instead of the interims? Were there any battles involving the MkIX for example where the MkVIIIs extra 50% fuel would have provided a significant advantage?

The long-range Spitfires might've helped the USAAF 1943 ETO campaign (ie. after the decision to bomb the targets in Germany proper, and before Merlin Mustang arrived), 1942-43-44 MTO campaign, and during the whole Pacific war.

MKVIII carried about 30% more fuel than the Mk.IX, 120 vs. 84/85 gals. My mooting wrt. LR Spitfires always includes both Mk.VIII and IX carrying the 29 imp gal tank behind the pilot (as it was the case with 'self-deploying' Mk.Vs in the MTO).Meaning that Spit VIII carries total of around 150 imp gals of internal fuel, to the joy, for example, of 8th AF bomber crews - make sure that LR Mk.VIIIs are deployed in the ETO - and to the anger & sorrow of LW fighter pilots.

 

[Rule of cool]

I wouldn't consider the Mk VIII a long range fighter, medium range maybe, but if the small tanks give about 450 miles range (150 radius) the Mk VIII might have 250 miles radius. That said, that could provide the first and last legs of an escort relay, and keep the longer range US fighters to fly out to 250 miles at the most efficient flight regime and push the 'total' escort radius out somewhat.

 

[airman]

Well, The Spitfires I could be updated to III and after to IV version. Spitfire VII used in Egypt, Libia and Asia and replaced by IX versions.

 

[tomo pauk]

I wouldn't consider the Mk VIII a long range fighter, medium range maybe, but if the small tanks give about 450 miles range (150 radius) the Mk VIII might have 250 miles radius. That said, that could provide the first and last legs of an escort relay, and keep the longer range US fighters to fly out to 250 miles at the most efficient flight regime and push the 'total' escort radius out somewhat.

See here for Mk.VIII having the 1265 mile range with 90 imp gal drop tank (=210 gals total) and after the allowance of 24.5 gals is subtracted. Perhaps 400-450 mile radius, call it 400 to be on the conservative side?

Note that I've suggested that additional fuel tank of 29 gals is also installed. Spitfire was getting about 5 miles per gallon in cruise, for another 145 miles of range. We might get to 450 mile radius, even while being conservative. Can cover more than well the raids above Ruhr, and above Hamburg.

 

[red admiral]

There's plenty of bits on how to increase Spitfire range to be similar to P-51 that seem very doable based on the historical mods across the various Mks e.g. Here

But the RAF wasn't trying to make a long range escort day fighter to operate with 8th AF, having earlier switched to night bombing and got good at this (NB it did make long range night fighters). I think the biggest change would need to be one of RAF day fighters switching to 8th AF escorts earlier as a wider strategy, and Supermarine managing to rapidly implement these changes - probably into a Mk IX mod? Which might mean forgoing the Griffon Spitfires?

Historical priorities always favoured the shorter term power and performance increases rather than longer term mods like longer range. Which sort of brings us back to the start of this thread.

 

[tomo pauk]

Historical priorities always favoured the shorter term power and performance increases rather than longer term mods like longer range. Which sort of brings us back to the start of this thread.

Once past the BoB, with Luftwaffe blunted, and especially later with the need for long range fighters in MTO, Asia and Pacific, there was enough of 'drivers' for the LR Spitfire. Unfortunately, it took until late 1944 for the LR (= has a lt of fuel) Spitfire - as well as Tempest - to materialize, by what time the American-made LR fighter were available by many months now. And in quantity, while the Allies were already well set in France.

 

[NOMISYRRUC]

Link to the Opening Post.

Does goes to plan include things like Supermarine completing its first contract (for 310 Spitfires) on time and the Castle Bromwich factory delivering its first aircraft on time?

 

[Rule of cool]

Something I just thought of is how long it took for the RAF deploy the Spitfire overseas, not until Mk Vs were deployed to Malta in March 1942.

IIUC the OP premise is that the Mk III with the Merlin 20 and 4 x 20mm cannon goes into service; does it provide the RAF with enough of an edge at home and NW Europe that the RAF is confident enough to send Spitfires to Malta earlier? If so, what impact would this have on the campaigns from that point forward?

 

[Calum Douglas]

Aircraft revisions were minor: clipped wings (reverted to the normal wings on the 2nd prototype), and a bit re-hashed and strengthened front fuselage because of heavier engine and more fuel carried. Different weapon set-ups were discussed, including two belt-fed Hispanos, while one series of 1000 aircraft was supposed to carry the usual 8 .303 battery.

As for the alternative time line, I'd go like this:
Mk.I - as is
Mk.II - Merlin III with pressure injection carb, less draggy exhausts (as the Bf 109D and He 112B have gotten), some protection for pilot and fuel (we should hopefully get into 370+ mph range now), has drop tank facility (yes, this requires some doctrine shift in the AM and RAF)
Mk.III - as per historical aircraft + better carb + better exhausts = 390+ mph in service; drop tanks can be carried; Mk.IIIB has cannons
Mk.IV - same as Mk.III, but with Merlin 45
Both marks can have easlily removable 29 imp gal tank behind the pilot, as it was the case with historical Mk.Vs for overseas deployment. Some have the Merlin 46 or 47.
Mk.V - the 1st Griffon-powered version, the 29 imp gal tank is the fixed accesory; standard battery consists of two cannons and 4 .303s
Mk.VI - placeholder
Mk.VII - 2-stage Merlin with the LE tanks (internal fuel is now almost 150 imp gals, giving the footprint necessary for operations in the Med and Asia/Pacific)
Mk.IX - Spitfire III and IV re-engined with 2-stage Merlin engines, standard internal fuel is a bit shy of 130 gals
Mk.X - Griffon power, on what is basic Spitfire III airframe

... more later

"minor".

This is really not true, the Mk-III had 100,000 man hours on design, in terms of the hours expended on a single Mark, this is exceeded ONLY by the original entire aircraft Mk1 (340,000 hours) and the Mk21 (170,000 hours).

Minor was something like the Mk II, which had 10,000 hours.

It had retractable rear wheel, very different wings, and boundary layer bypass radiators like the 109F.

 

[Dagger]

Justo, which book is 090.jpg from?

It is from "The Spitfire Story" by Alfred Price.

 

[tomo pauk]

This is really not true, the Mk-III had 100,000 man hours on design, in terms of the hours expended on a single Mark, this is exceeded ONLY by the original entire aircraft Mk1 (340,000 hours) and the Mk21 (170,000 hours).

Minor was something like the Mk II, which had 10,000 hours.

Thank you.
Mind you, British have had the Mk.III as an actual, flying prototype by mid 1940, so that and other expense seems to be working out.

It had retractable rear wheel, very different wings, and boundary layer bypass radiators like the 109F.

About the wing, from 'Spitfire' by Morgan & Shacklady, pg. 128 (my emphasis in bold):
Wing surface: The wing area is slightly reduced without interfering with the main structural members, except at the tip where the area is removed.

Preceding page notes that "... and the wings had a 3.5 ft section removed from each tip ... " [when compared with the Mk.I that also the N3279 was supposed to be, before modified into the Mk.III, being removed from the production line at Woolston prior to that]. Freeman wanted that the last 200 Mk.Is off the production lines are to be brought to the 'Superiority Spitfire' - nickname of the Mk.III.
The N3279 was later outfitted with 'normal span wings, as requested by Dowding'. Dowding was worried that squared wing tips will have the pilots mixing up the Mk.III with Bf 109E, and he also wanted a bit lower wing loading for the Mk.III.

We can compare that with what was changed on the Bf 109 from E into F in the same time - a really new wing, new cooling system, new tail without external bracing for horizontal stabilizer, retractable tailwheel, all new nose, ability to carry and reliably use the motor cannon - these are just the plainly visible things.

 

[pathology_doc]

It is from "The Spitfire Story" by Alfred Price.

ADD TO CART.

Amazon had a used copy going for relatively cheap. It also had a placeholder for a much older edition, with a cover picture that looks significantly like the one I saw in Manchester.

It's on the way.

 

[EwenS]

Something I just thought of is how long it took for the RAF deploy the Spitfire overseas, not until Mk Vs were deployed to Malta in March 1942.

IIUC the OP premise is that the Mk III with the Merlin 20 and 4 x 20mm cannon goes into service; does it provide the RAF with enough of an edge at home and NW Europe that the RAF is confident enough to send Spitfires to Malta earlier? If so, what impact would this have on the campaigns from that point forward?

Firstly, at the end of 1940 it was believed that Fighter Command needed 80 single engined day fighter squadrons to defend the UK in case the Luftwaffe came back for a second BoB. From 60 in Feb 1941 it peaked at 74 in Sept, before transfers overseas reduced the numbers back to 70 in Jan 1942.

Those figures hide 2 things.
1. Many squadrons formed on Hurricanes in 1941
2. Many squadrons re-equipped with Spitfires in 1941.

So the Spitfire / Hurricane mix went from 22 /38 in Feb 1942 to 58 / 12 in Jan 1942. That is an awful lot of extra Spitfires needed for Fighter Command, regardless of model, and not accounting for any losses in 1941. Unless somehow Fighter Command somehow changed its mind about the number of squadrons required. It was Aug / Sept 1941 before the British Chiefs of Staff felt confident enough that an invasion wasn't going to happen in 1941 and confident enough to release forces for the MIddle East (1 infantry division and 7 Hurricane squadrons left Britain intended for the Middle East in late 1941 for example).

Malta
The Luftwaffe attacks on Malta came in phases, driven largely by what was going on elsewhere. So there had been a lull between April & Oct 1941 during which Hurricane II had proved adequate for the task of defending the island. The Luftwaffe offensive against Malta restarted in Dec 1941 in an effort to reduce the effect that ships, aircraft and submarines based there were having on Axis supply convoys. And the Luftwaffe were now using the Bf109F which outperformed the Hurricane II. IIRC the Governor of Malta reported to Churchill in Jan 1942 the dire situation the island was in and the need for Spitfires. By mid-Feb there were few servicable fighters on the island.

The first Spitfires were dispatched from Britain on 16 Feb 1942, transferred to Eagle at Gibraltar and flown off to Malta on 7 March 1942.

Details of aircraft deliveries to Malta can be found here

The Supply of Malta 1940-1942 by Arnold Hague

At the same time Spitfire squadrons were embarking for the Middle East. For example 92 & 145 left Britain on 11 Feb and reached Egypt, via the Cape, on 16 April. But there were delays in getting enough Spitfires to them to make them fully operational immediately due to diversions to Malta.


Conclusion
I doubt having Mk.III Spitfires available in Britain instead of Mk.V makes any difference to the numbers game.

As for Malta & the Med, the driving factor seems to have been the arrival of the Bf109F which was outperforming the Hurricane II. And that didn't show up until late 1941.

So no, I don't see Spitfires being released from the UK any earlier without some other change on the Luftwaffe side.

 

[Rule of cool]

That's a great explanation and the numbers are inarguable, but what about the vibe? As you state FC went from a Hurricane dominant force in early 41 to a Spitfire dominant force by by early 42, however these relative squadron numbers reflect an assessment of need. What if that assessment meant that the ratio of Spitfires didn't need to be quite so high, instead of 58:12 by early 42 they assessed that getting there by mid 42 to free up some(a handful, say 3?) sqns for Malta in that same shipment of the infantry division and 7 Hurricane sqns? 3 Spitfire sqns on Malta at the start of the Luftwaffe assault could be a godsend and be a small risk for British security.

 

[EwenS]

The wartime policy saw the following order of priority:-
1. Home Front (without it the war in other theatres is lost)
2. Middle East (determined to be second from Aug 1941)
3. Far East (which got virtually nothing until after 8 Dec 1942 - 7 Dec for the USA)

The fighter threat in West was the Bf109F from late 1940 and the emerging Fw190 from Aug 1941 (which already out performed the Spitfire V let alone the Hurricane II). As I noted the Bf109F threat emerged later in the Med. So where is the greatest need for Spitfires?

Your plan means changing the carefully thought out Govt policy, not just that of the Chiefs of Staff or Fighter Command. And it is not just a question of sending say 3 squadrons overseas. You also need to continue to supply them with new aircraft to keep them operational. Look how many Spitfires were flown from carriers to Malta in 8 months in 1942 - 384.

That infantry division & about 4 of those Hurricane squadrons ended up diverted to the Far East as the war there broke out while they were in transit. 1.5 went by carrier to Malta before Ark Royal was sunk while the other 1.5 ended up in Egypt via a flight across Africa from Takoradi because there was no carrier to transport them to Malta.

By early 1942 the whole pattern of the war has changed. The Allies can be happier that with Lend Lease supplies flowing, and Hitler having been stopped at Moscow, the USSR was not going to collapse, as was believed possible in summer 1941 (at which point the Axis threat would have turned back to Britain). The idea that Spitfires could be sent overseas in 1941 relies purely on hindsight because the perceived threats in summer 1941 didn't emerge.