# Spitfire V Versus P-40E (1 Viewer)



## MIflyer (Jul 14, 2020)

I have no idea where I found this item. I do not even recall downloading it and found it by accident today while looking for something else. In case y'all have not seen it, here it is. Some of the results of this fly-off competition are quite predictable but others are not. I wonder how a P-40F would have fared.

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## GregP (Jul 15, 2020)

Very interesting indeed, but I bet everyone would like to see the document. Thanks for sharing the results.


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## MIflyer (Jul 15, 2020)

The Spitfire V was a much better air to air fighter than the P-40E; I do not think anyone would dispute that. I don't think anyone would prefer flying P-40E to a Spit V in air to air combat. But even the E model P-40 was a vastly better fighter bomber than any mark of Spitfire, having more range, a larger bombload, built stronger, and being more resistant to ground fire. I even recall one highly experienced WWII/Korea fighter pilot saying he thought the P-40 was a better fighter bomber than the P-51, because you were much less likely to get hit in the nose radiator rather than one on the belly.

But to see them conclude that the P-40E was as good or better than the Spit V below 16,000 ft, including having a higher roll rate is surprising to me. 

It is not hard to see why the Kiwis and Aussies were fairly pleased with the P-40 in the Pacific, or that the RAF in Europe kept flying P-40's in the fighter bomber role all the way into 1945.


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## GregP (Jul 15, 2020)

The P-40 had one of the best roll rates for an American fighter. It didn't turn as well as the P-36 with the radial engine, but it also wasn't a slouch. Being built to a different standard, it was heavier and didn't climb as well as a Spitfire, but this is the first time I have seen a claim that it was as good in a dogfight at 16,000 feet and below.

This goes a long way toward explaining why P-40s in North Africa did well against Bf 109Es. They were fighting much lower than they were in the ETO. I already knew they were fighting lower, but did not suspect they were as good as a Spitfire V at those altitudes. I also am not taking that at face value, but it DOES elevate the P-40 a bit in perceived capabilities.

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## MIflyer (Jul 15, 2020)

The pilots who flew the "Clipped, Cropped, and Clapped" Spit V reported that it was the hottest thing they ever flew below 10,000 ft. Cropping the supercharger blades enabled full power to be applied at low altitudes and clipping the wingtips improved the roll rate as well as speed. Now, the P-40's were mostly set up for max performance at about 15,000 ft, that being a happy medium with a single stage single speed engine. In contrast, the A-36A had a V-1710 engine set up for max performance at about 5000 ft. Funny that no one ever seemed to try producing an LF P-40; maybe it was already good enough in that regime. 

And Fornoff, the famous Grumman test pilot, also said that the P-40 accelerated a lot faster than the F6F.

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## Kevin J (Jul 15, 2020)

MIflyer said:


> The Spitfire V was a much better air to air fighter than the P-40E; I do not think anyone would dispute that. I don't think anyone would prefer flying P-40E to a Spit V in air to air combat. But even the E model P-40 was a vastly better fighter bomber than any mark of Spitfire, having more range, a larger bombload, built stronger, and being more resistant to ground fire. I even recall one highly experienced WWII/Korea fighter pilot saying he thought the P-40 was a better fighter bomber than the P-51, because you were much less likely to get hit in the nose radiator rather than one on the belly.
> 
> But to see them conclude that the P-40E was as good or better than the Spit V below 16,000 ft, including having a higher roll rate is surprising to me.
> 
> It is not hard to see why the Kiwis and Aussies were fairly pleased with the P-40 in the Pacific, or that the RAF in Europe kept flying P-40's in the fighter bomber role all the way into 1945.


The VVS preferred the Kittyhawk to the Spitfire Vb. It had overboost too.

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## PAT303 (Jul 15, 2020)

MIflyer said:


> But to see them conclude that the P-40E was as good or better than the Spit V below 16,000 ft, including having a higher roll rate is surprising to me.



The MkV was designed as a high altitude fighter, if you want to fight low use the LF version.

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## GregP (Jul 15, 2020)

If you're going to pick and choose your Spitfire, then you might was well pick and choose your P-40. I'd try the P-40F or P-40M if you're going to use an LF Spitfire. If I could pick ANY P-40, I'd take an XP-40Q-2/3! The LF Spit might not know what hit him.

Of course, you could also choose a Spit XIV. So, we might as well just let the Mk.V and the P-40E go and accept the existing report ... maybe. Perhaps there is another report on comparative combat between two different models of Spitfire / P-40. I haven't heard of THIS one until now ... so maybe there are more?

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## wuzak (Jul 16, 2020)

GregP said:


> If you're going to pick and choose your Spitfire, then you might was well pick and choose your P-40. I'd try the P-40F or P-40M if you're going to use an LF Spitfire. If I could pick ANY P-40, I'd take an XP-40Q-2/3! The LF Spit might not know what hit him.



The LF.V was not a new model - just used a revised (low altitude) engine and changed the wing tips for the "clipped" versions.

The LF.IX was the F.IX with the Merlin 66 and it would very much be competitive with the P-40Q.

So how the battle between the LF Spitfire and P-40Q depends on which LF Spitfire.




GregP said:


> Of course, you could also choose a Spit XIV.



The XIV would be the closest contemporary Spitfire to the P-40Q, but probably 6 months to a year ahead.




GregP said:


> So, we might as well just let the Mk.V and the P-40E go and accept the existing report ... maybe. Perhaps there is another report on comparative combat between two different models of Spitfire / P-40. I haven't heard of THIS one until now ... so maybe there are more?



It is an interesting report, showing that the P-40E had difficulty gaining advantage, but could disengage from the fight using superior speed and dive ability.

Certainly the removal of the tropical filter would have evened up the speed and reduced the diving deficit.

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## Shortround6 (Jul 16, 2020)

I believe we have been over this before, the Spitfires the Australians got had Merlin 46 engines and not Merlin 45s. The Merlin 46 had a bigger impeller and worked better at higher altitudes but had around 100hp less than a standard Merlin 45 at lower altitudes. For some reason the Australians also limited the boost on the Merlin 46s to 9lbs. 
British at some point in time allowed 16lbs boost for the Merlin 46.

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## PAT303 (Jul 16, 2020)

GregP said:


> If you're going to pick and choose your Spitfire, then you might was well pick and choose your P-40.



The test used a MkV fitted with a Merlin 46, an engine specifically designed for high altitude. When the fight started at 20,000ft it was all over in 2 minutes with the Spit owning the P40, but when they started at 16,000 and 13,000ft were the 46 only produced about 1,000hp the fight was more or less equal.

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## soaringtractor (Jul 16, 2020)

GregP said:


> If you're going to pick and choose your Spitfire, then you might was well pick and choose your P-40. I'd try the P-40F or P-40M if you're going to use an LF Spitfire. If I could pick ANY P-40, I'd take an XP-40Q-2/3! The LF Spit might not know what hit him.
> 
> Of course, you could also choose a Spit XIV. So, we might as well just let the Mk.V and the P-40E go and accept the existing report ... maybe. Perhaps there is another report on comparative combat between two different models of Spitfire / P-40. I haven't heard of THIS one until now ... so maybe there are more?


Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!! The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!

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## Schweik (Jul 16, 2020)

This has been around for a while and discussed in several threads. I'd like to point out a couple of things though -

The P-40E and Spit V weren't really contemporaries in action, at least not as fighters. P-40E was being phased out mainly for the K in the Pacific (by US, Australian and NZ units) by the time the Spit V showed up. Other P-40E were up-engined to the K standard (V-1710-73). At the end of 1943 they started getting the N. In the Med there were some old P-40D and E still around when the Spit V arrived but they had been relegated to fighter bomber missions, whereas 5 of the 7 US fighter groups in the Theater used P-40 F/ L (merlin engine) and the British and Australians were using P-40K and M, with two squadrons flying the F/L. 
P-40 units (notably US 49th FG) had better luck against Zeros in the defense of Darwin, though the issues with the Spit V in that action may have been mostly maintenance related.
The P-40F/L (or most of them) greatly reduced the longitudinal stability issues mentioned in the report by extending the length of the fuselage about 3 feet.
If the P-40E shows up that well against a Spit V, you can assume that the P-40K would have a more substantial advantage down low (it had about 100 more horsepower and could be overboosted to about 300 more hp), and the P-40F /L had more HP + the additional advantage of a much higher critical altitude (about 18,000 ft vs. 12,000 for the P-40E).
The Spit could outmaneuver the P-40 but the P-40 was one of the most maneuverable Allied fighters, and could out turn the Bf 109, MC 202, and Yak 7 among others.
All versions of the P-40 were reportedly able to disengage from all Axis fighters except the Fw 190 by diving away.
Based on combat records and losses on both sides (Mediterranean Air War III and IV) the US P-40 units, flying P-40F and L, did as well as the Spitfire units against German and Italian fighters, and definitely took fewer losses than the P-38 units operating in the same areas.


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## Schweik (Jul 16, 2020)

soaringtractor said:


> Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!!



That isn't true. The merlin powered P-40's performed much better at higher altitude, which was really what mattered especially against German and (German engined) Italian fighters. That is why all the US Units used the P-40F and L in North Africa - 33rd FG, 57th F, 324th FG, 325th FG, and 79th FG, plus the 99th FS (Tuskeegee)



> The spitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!



Unless fitted to a turbocharger as in the P-38, the Allison was basically only good up to about 12,000 ft for most models, depending on the gearing. Some were good up to roughly 16,000 ft. Generally speaking the Merlin was better.

The P-40F (with the Merlin XX) had two speed supercharger and therefore two good critical altitudes. The Allison was a little better down very low but the lack of high altitude performance was a major problem (according to the USAAF among others).

Early (Allison engined) Mustangs (P-51A and A-36 dive bomber) had a poor combat record in air to air engagements, notably in China / Burma. Apparently they had an issue with the aileron which was later fixed with the B and C models. THere was only one Ace that flew Allison engined P-51s vs. I don't know how many hundreds with the P-51B and later models. There is absolutely zero doubt that the Merlin engined Mustang performed far better and had a combat record orders of magnitude better than the Allison engined ones. The Allison-Engined P-51s basically had a niche as recon planes.

Nobody is lying about the Allison engine.

You don't need to be so belligerent. The P-40 was good, but the Spitfire was a great fighter. That's just a fact.

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## pbehn (Jul 16, 2020)

soaringtractor said:


> Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!! The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!


Always nice to read someone showing their real appreciation of the Brits wisdom in ordering the Mustang MkI in the first place.


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## Schweik (Jul 16, 2020)

I apologize to the forum in the name of citizens of the United States. We aren't having a great moment right now.

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## GregP (Jul 16, 2020)

Hi Soaringtractor,

Every country in WWII was nationalistic ... ALL of them. The British were no different than we were in that regard. Not sure the British lied about anything, but their flight reports generally limited the Allison to some lower boost than was used in combat while the Merlins in their tests were boosted to what WAS used in combat. That isn't exactly a lie since the test conditions were printed in the reports.

I do not think the P-40F had lower performance than the Allison P-40s. It was very similar in performance to the Allison P-40 at 16,000 feet and below but was slightly better at higher altitude because the Merlin used, a single-stage Merlin 28/219 unit, had a larger supercharger impeller. I would have liked to have seen a 2-stage Merlin P-40 myself.

The Allison was and IS a good engine, but so is the Merlin. Different approaches to the same problem. The Allison was more robust and would hold a tune longer, but there was and IS nothing wrong with the Merlin engine ... it has a solid place in history that is inevitably a bit above the Allison in performance, especially the 2-stage units. I have a friend who overhauls Allisons and I worked with him on Allisons for several years. Great engines that spank Merlins on the tractor-pull circuit.

The biggest problem with the Allison these days is that Rolls-Royce bought the Allison rights and name, and has no interest in promoting it whatsoever. That, unfortunately, is the right of the owner.

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## MIflyer (Jul 16, 2020)

Schweik said:


> You don't need to be so belligerent. The P-40 was god, but the Spitfire was a great fighter. That's just a fact.



I think you mean "The P-40 was Zeus but the Spitfire was Jehovah."

The RAF would have lost the BoB if they'd had Hawk 81A's instead of Spitfires. On the other hand, if the RAF had a hundred or so operational Hawk 81A's together with the required pilots they could have proved to be a nasty shock to tired BF-109 pilots straggling in over France watching their Low Fuel Warning Lights instead of their tails.

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## Sid327 (Jul 16, 2020)

soaringtractor said:


> Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!! The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!




Not very biased are you...
I see you have found your way onto this forum after poisoning thousands of Youtube videos which showed anything British with your foul mouthed remarks and not only bitter but childish attitude. I wouldn't be surprised if you were the most unpopular person on Youtube and that includes your other alias usernames too.
Hopefully the administration on here are wise to what you are really like.

[Note: search Youtube 'soaringtractor'].


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## Schweik (Jul 16, 2020)

MIflyer said:


> I think you mean "The P-40 was Zeus but the Spitfire was Jehovah."
> 
> The RAF would have lost the BoB if they'd had Hawk 81A's instead of Spitfires. On the other hand, if the RAF had a hundred or so operational Hawk 81A's together with the required pilots they could have proved to be a nasty shock to tired BF-109 pilots straggling in over France watching their Low Fuel Warning Lights instead of their tails.



Ooops my bad, fixed.


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## wuzak (Jul 16, 2020)

GregP said:


> Not sure the British lied about anything, but their flight reports generally limited the Allison to some lower boost than was used in combat while the Merlins in their tests were boosted to what WAS used in combat. That isn't exactly a lie since the test conditions were printed in the reports.



I'm sure that the boost used in tests were the recommended boost levels, which may have been exceeded on the front lines (at very low altitudes).


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## wuzak (Jul 16, 2020)

soaringtractor said:


> The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them.



That'd be why the kept Spitfire V for themselves and farmed out the P-40s to the colonies and secondary fronts.

The British (and French) considered the P-40 to be the best available fighter _from the USA_. And in production.




soaringtractor said:


> It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war.



The P-40 was produced long past its use by date, as was the Hurricane.

In any case, it was useful as an advanced trainer.

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## Schweik (Jul 17, 2020)

wuzak said:


> I'm sure that the boost used in tests were the recommended boost levels, which may have been exceeded on the front lines (at very low altitudes).



Actually that isn't true, most of the tests, at least the ones we have access to, were done at low boost of 45" Hg, vs. the approved max of 54" - 57" Hg for most Allison variants, and 60" for Merlin. Basically it was the same issue as with the Spit. Performance differed greatly depending on the amount of boost used.


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## Greyman (Jul 17, 2020)

Approved max when, is the key question I think.


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## Kevin J (Jul 17, 2020)

wuzak said:


> That'd be why the kept Spitfire V for themselves and farmed out the P-40s to the colonies and secondary fronts.
> 
> The British (and French) considered the P-40 to be the best available fighter _from the USA_. And in production.
> 
> ...


Being a bit negative, aren't we?


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## Schweik (Jul 17, 2020)

Greyman said:


> Approved max when, is the key question I think.



By mid 1942 generally


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## MIflyer (Jul 17, 2020)

A P-40E pilot in the PI wrote that when the Japanese attacked he jumped in his airplane and took off, desperately trying to get out from under the rain of bombs. He looked at his manifold pressure gauge and was horrified that it only read about 15 inches. Clearly there was something badly wrong with the engine and he figured he was sunk. But as he sped away from the airfield and climbed for altitude he was surprised to see the pressure gauge go DOWN further, eventually beginning to show a pressure in the 50's. He had shoved the throttle forward and the engine, lacking an automatic manifold pressure regulator, had responded by producing manifold pressure so high that the gauge needle went past the top end and started another trip around the dial.

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## MIflyer (Jul 17, 2020)

wuzak said:


> The P-40 was produced long past its use by date, as was the Hurricane.



In the book "They Flew Hurricanes" an RAF pilot describes his frustration with why it was so long that they got nothing but Hurricanes in the Western Desert and on Malta rather than any Spitfires. "They have five thousand Hurricanes in the U.K. and they have nothing else to do with them."

In the P-40 training manual it is stated that they no longer send P-40's overseas and they have been replaced in combat zones by P-38's, P-47's, and P-51's but that they made great trainers.

Even the Mexican and Brazilian units we equipped and sent overseas got P-47's.

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## Kevin J (Jul 17, 2020)

MIflyer said:


> In the book "They Flew Hurricanes" an RAF pilot describes his frustration with why it was so long that they got nothing but Hurricanes in the Western Desert and on Malta rather than any Spitfires. "They have five thousand Hurricanes in the U.K. and they have nothing else to do with them."
> 
> In the P-40 training manual it is stated that they no longer send P-40's overseas and they have been replaced in combat zones by P-38's, P-47's, and P-51's but that they made great trainers.
> 
> Even the Mexican and Brazilian units we equipped and sent overseas got P-47's.


The Brits need the Tornado in service in 1942 for overseas use but powered by a P&W-2800. The Aussies need the Boomerang in service in 1942 with a GE B-2 turbo in it as per the CA-14A.


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## Schweik (Jul 17, 2020)

MIflyer said:


> A P-40E pilot in the PI wrote that when the Japanese attacked he jumped in his airplane and took off, desperately trying to get out from under the rain of bombs. He looked at his manifold pressure gauge and was horrified that it only read about 15 inches. Clearly there was something badly wrong with the engine and he figured he was sunk. But as he sped away from the airfield and climbed for altitude he was surprised to see the pressure gauge go DOWN further, eventually beginning to show a pressure in the 50's. He had shoved the throttle forward and the engine, lacking an automatic manifold pressure regulator, had responded by producing manifold pressure so high that the gauge needle went past the top end and started another trip around the dial.



This became increasingly common in both the Pacific and the Med, and the Allison company responded by hardening some parts in the engine (crank shaft and crank case among others) to better endure higher pressure. Eventually they moved the normal boost limit from 45" Hg to 54" and then ultimately 57" or 60" (P-40K) but this took a while to filter back to the flight manuals, and in some cases never did. 45" became the military power setting and 57" the WEP.

It echoes changes made to official boost settings for other aircraft like the Spitfire.

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## Schweik (Jul 17, 2020)

MIflyer said:


> In the book "They Flew Hurricanes" an RAF pilot describes his frustration with why it was so long that they got nothing but Hurricanes in the Western Desert and on Malta rather than any Spitfires. "They have five thousand Hurricanes in the U.K. and they have nothing else to do with them."
> 
> In the P-40 training manual it is stated that they no longer send P-40's overseas and they have been replaced in combat zones by P-38's, P-47's, and P-51's but that they made great trainers.
> 
> Even the Mexican and Brazilian units we equipped and sent overseas got P-47's.



That depends what time period. They were still using P-40s actively on the front line in Italy, Burma, and the South Pacific in 1944. And they were still scoring victories.


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## MIflyer (Jul 17, 2020)

I believe the last RAF P-40 pilot KIA was in 1945. So they hung onto the tough old birds almost to the very end. The Dutch in the East Indies were still flying them against insurgents in 1947. The P-40 made a much better dive bomber than any mark of Spitfire. P-51 pilots flying short range ground attack missions in Korea often wished they had P-40's instead.

A friend of mine knew a WWI pilot who had worked at Allison before he went back into the service in WWII. He said that they ran the V-1710's up to 80 inches manifold pressure on the factory test stand and the only problem was that the bolts holding it down started breaking. Merlins modified for racing often use V-1710 piston rods because they are stronger. 

Funny thing was that the P-40M, built exclusively for the British Empire, was the first to incorporate an automatic manifold pressure regulator, but one of the RAF comments was that you can disable the regulator and get better performance out of it. 

And yet there are people today that will tell you that if you exceed 60 inches HG with a V-1710 or a V-1650 the whole engine will dismantle itself within seconds - or that you will gain no extra performance by overboosting it at lower altitudes..

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## Schweik (Jul 17, 2020)

60" became standard for the V-1710-73 (standard on the P-40K)

The P-40M was basically designed to be a fighter bomber and had a higher gear ratio so that it's critical altitude was up around 14k ft instead of 12k ft like the V-1710-39 on the original P-40D/E (Kittyhawk I and Ia for the Brits). But this also meant that it wasn't as safe to boost the engines so high down low, which Allison warned about in their famous memo.

The confusing thing for the British was that they designated both the P-40K and P-40M as "Kittyhawk III" but they had very different performance. The P-40K peaked at around 12,000' ft but could be boosted to 70" apparently, down around 3,000' or lower (and officially to 60" up to about 7,000 ft) whereas the P-40M was probably safest at around 57" especially down low... which is still pretty good performance but it's not quite the beast that the P-40K was. The K models were in demand and British and Australian pilots mentioned "stealing" certain Kittyhawk III's from units that had them. Bobby Gibbes described an incident in which he was piloting a "stolen" Kittyhawk III and jumping ahead of a squadron of Kittyhawk II's (P-40F) he was leading to shoot down a Bf 109 that was flying over them.

Another American pilot described in a letter to his family a running fight he had with two Bf 109s as he was fleeing back to his base, in which he managed to stay ahead of them and eventually shot one of them down by sticking to 60" Hg boost. It's unclear if he was in a P-40L or a P-40K, as his units had some K models at the time due to a shortage of the Packard-Merlin 28 engines.

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## Schweik (Jul 17, 2020)

One other point worthy of note, the RAF stopped using P-40s as front line fighters by the end of 1943, and in 1944 they were using them just as fighter bombers. They did still occasionally get victories when defending themselves against Axis attacks but the rate dropped off a lot, most of their losses were to flak. The Americans had some fighter groups that continued with P-40's in the MTO until May or June of 1944 by which time they were being replaced with P-47s and later in turn, P-51s.

The USAAF continued using P-40s in Burma until early 1945. In the Pacific they were gradually replacing them with P-38s but it took a long time, some units (I think two of the three squadrons of the 49th FG for example still had P-40s until late 1944). The Australians transitioned to Spitfire VIII in 1944 and the New Zealanders to Corsairs, but by that time they were kind of out of the fight.


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## GregP (Jul 17, 2020)

I can tell you from personal experience working in an Allison shop that 57" and 3000 rpm are conservative for the V-1710.

Tractor pull guys turn them at 4000 rpm with no damage, but most of these guys have the crankshaft with 12 counterweights. We had one guy turn his at 5000 rpm by "mistake." It is installed in a race car and he was paying attention to a scantily-dressed lady instead of his starting technique and accidentally started it at wide open throttle! Yes, it broke, but no catastrophically. They have no trouble and no damage from running at 75", but that should include a run time. I would not want to run one at 75" for 30 minutes unless I was trying to save my own life, but a burst of power at 75" for a few minutes would not be out of line.

There is nothing "delicate" about a V-1710 Allison. It is a solid, good-running engine.

The best engines in the fastest at the Reno National Championship Air Races are not really "Merlins." Yes, they have a base Merlin engine, usually a transport engine, but the parts are diverse. Most of the really fast "Merlins" use Allison V-1710 G-series pushrods, custom pistons, modern ignitions, and a host of modern engine technology to produce 3,850 hp at 3400 or 3600 rpm and 140+ inches of MAP. They can do this for about 2 - 3 laps and then need to cool down a bit or else they tend to throw a scrap iron fit.

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## Schweik (Jul 17, 2020)

I think the main issue with the WW II engines was the supercharger gear ratio. Higher ratio allowed better performance at higher altitude but it out more strain at lower altitude. Reno air races are done pretty low right?

At 70" Hg a P-40 was a beast. That is almost 40% more power than in the test in the OP.


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## pbehn (Jul 17, 2020)

A testing establishment runs the tests its clients wants them to run, to give the results they want. An aircraft testing establishment wasn't a bunch of petrol heads seeing how fast they could make things go.


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## Schweik (Jul 17, 2020)

I'm not alleging any conspiracy.


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## PAT303 (Jul 18, 2020)

Schweik said:


> This became increasingly common in both the Pacific and the Med, and the Allison company responded by hardening some parts in the engine (crank shaft and crank case among others) to better endure higher pressure. Eventually they moved the normal boost limit from 45" Hg to 54" and then ultimately 57" or 60" (P-40K) but this took a while to filter back to the flight manuals, and in some cases never did. 45" became the military power setting and 57" the WEP.
> 
> It echoes changes made to official boost settings for other aircraft like the Spitfire.



Boost pressure was governed by fuel octane/Performance number ratings not the engine it'self, hardening of parts was mainly for increased wear resistance to extend overhaul times.


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## Greyman (Jul 18, 2020)

PAT303 said:


> Boost pressure was governed by fuel octane/Performance number ratings not the engine it'self ...



Not if the aircraft had no automatic boost control -- which most US fighters were lacking in the first couple of years. 

Altitude and throttle setting (accidental or intentional) played a starring role in those cases.


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## Acheron (Jul 18, 2020)

I thought the P-40 was quite a good plane at low altitudes and just suffered a massive drop in performance at high altitudes, am I mistaken?

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## PAT303 (Jul 18, 2020)

MIflyer said:


> The pilots who flew the "Clipped, Cropped, and Clapped" Spit V reported that it was the hottest thing they ever flew below 10,000 ft.



MkV LF's running 50 series Merlins were good for 350mph below 10,000ft.


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## Kevin J (Jul 18, 2020)

PAT303 said:


> MkV LF's running 50 series Merlins were good for 350mph below 10,000ft.


The P-40K should have been good for 344 mph at sea level and 364 mph from 5000 to 15000 feet, same as the A-36 which had dive brakes and bomb racks. You'd want to use the LF VB for close escort and dive bombing, the P-40M for medium level cover alongside the F VC.


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## MIflyer (Jul 18, 2020)

Th e P-40 was the King of Mediocrity. It was fast enough at lower altitudes to be competitive but usually not fast enough for it to be a decisive advantage. It was very maneuverable but not as good as the Spitfire, Zero, or Oscar. It had longer range than the Spitfire, Hurricane, BF-109, FW-190, but not enough to be a long range bomber escort. It was rugged and made a better ground attack airplane than Spitfire, Hurricane, BF-109, Zero, Oscar, and probably about as good as a Typhoon, but not nearly as good as a P-47D. 

It's been said that when it came to air to air fighting the Merlin Mustang never met an adversary it could not outperform in at least one critical area; the reverse was true of the P-40.

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## Kevin J (Jul 18, 2020)

MIflyer said:


> Th e P-40 was the King of Mediocrity. It was fast enough at lower altitudes to be competitive but usually not fast enough for it to be a decisive advantage. It was very maneuverable but not as good as the Spitfire, Zero, or Oscar. It had longer range than the Spitfire, Hurricane, BF-109, FW-190, but not enough to be a long range bomber escort. It was rugged and made a better ground attack airplane than Spitfire, Hurricane, BF-109, Zero, Oscar, and probably about as good as a Typhoon, but not nearly as good as a P-47D.
> 
> It's been said that when it came to air to air fighting the Merlin Mustang never met an adversary it could not outperform in at least one critical area; the reverse was true of the P-40.


2000 aerial victories for the USAAF, 800 for the Commonwealth, 250+ for the AVG, must be at least 500 for the USSR as they thought it better than the Hurricane so maybe 800 not 500. That takes its total score past the Lightning.

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## Schweik (Jul 18, 2020)

Milflyer is right in one sense: the p-40 was not world's greatest in any particular category. And on paper it looked kind of mediocre. But Kevin j is right the operational history shows that the P-40 was succeeding in every theater of the war where they used it far better than expected. That is why it remained in combat for so long even though it was supposedly so bad.

Part of the reason the strength of the Allison engine, the strength of the airframe and the maneuverability inherent in the design by Don Berlin. And the ingenuity of the pilots whose refusal to accept their fate, notably early on the Australian pilots in the Western Desert which made them some of the first to figure out how to exploit the strengths and understand the limitations of the p-40 (as well as much more famously, the AVG).

Once the advantages and disadvantages of the plane were better understood, in the Pacific, in Russia, in the western desert, and in China / Burma the p-40 was a known quantity which experienced pilots were able to exploit to do what fighters are supposed to do: shoot down enemy aircraft and bring their pilot home.

Its main advantages were very high dive speed (which could go far over the flight manual limit) good turn rate, excellent roll rate, heavy construction and armor, and good firepower. The engine turned out to be more powerful than it was rated for and the pilot exploited that.The main reason that it was successful was that p-40 pilots knew their combination of maneuverability and dive speed (or low altitude speed) made it able to disengage when the pilot really wanted to most of the time. This was true fighting against the Germans and Italians as it was against the Japanese. And that is the really key thing for a fighter. (The ability to disengage was also the main advantage of the P 51).

The really major disadvantage or Strategic flaw was it's poor high altitude performance as Acheron mentioned. That was the strategic limitation, that is why it could not escort heavy bombers and why it gave up the tactical advantage especially to the BF 109, and that is why the air force generals despised it, even though a lot of the pilots who flew it loved it

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## Schweik (Jul 18, 2020)

The high maneuverability & the ability to pour on the coal when you needed to such as by overboosting also made it easier to get those shots against a fleeing or maneuvering Target. On the other hand like a lot of fighters with wing mounted guns p-40s and trouble with jamming machine guns in the early years. That was another thing that was mostly fixed with the p40 k or f and later.

I suspect the p 40K could do better than 360 miles an hour down low if it was over boosting as high as they reported they were but nobody ever clocked it at 70 in of Mercury. Both p40 k & f /l models were reportedly able to outrun BF 109 at low altitude on several documented occasions


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## Schweik (Jul 18, 2020)

speaking of which in the test from the original post it's possible that the p-40 e they were testing with had an upgraded engine from a p 40K. The Australians began replacing a original V-1710- 39 with the v 1710-73 on some of their P-40E's in 1942.

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## Acheron (Jul 18, 2020)

If the P-40 was truely mediocre all around, then I guess it boiled down to forcing the enemy into a way of combat where is plane was sub-par and avoid types of engagements where his was above the norm? Though that was true of pretty much every aircraft I would say, though some advantages (like speed) where easier to force onto te opponent than others (like maneuverability).


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## Schweik (Jul 18, 2020)

Yes, that is true. Every fighter had it's limitations and advantages and the key to using them was figuring out what the parameters were precisely, both for your aircraft and that of your enemy. That is why the Zero became easier to face after they tested it.

With the P-40 it's just that the low to medium altitude limitation was a major problem. In particular against the Germans, the enemy would usually gain the altitude advantage and therefore the option of first attack. That is another way fighter aircraft were successful - being able to choose when and where to attack. As we know, some large percentage of attacks took place without the target even realizing they were about to get hit.

For the (RAF, initially) P-40 units in the MTO what this meant was they had to develop tactics to deal with the potential of attack from above. The Germans were free to roam around in relatively small groups - a flight of four could patrol safe from attack at 25,000 ft. And for 1941 and the first few months of 1942 they were often able to pick off Allied fighters by swooping down on them unawares and picking them off, then climbing back up out of reach. It wasn't decisive, it was a low risk means of attrition warfare, and it didn't work in escort situations - if they wanted to shoot down bombers they had to force the issue which gave the P-40s and Hurricanes a better chance to get them. But they were able to keep picking away.

To be fair to the P-40, for whatever reasons (possibly Tropical filters) Hurricanes and the early (Mk V) Spitfires also seemed to be vulnerable to this problem and were routinely attacked from above, though the Spit V was the least vulnerable of the three.

To counter this the RAF developed tactics where they would always fly in a squadron formation (no tooling around in flights of four), watch the skies very carefully and when attacked, notify the leader with a couple of clicks of the mic button, then wait for the squadron leader to call "Break Right!" or "Break Left" at just the right instant when the enemy plane was diving down, and then pour on the coal and use their sharp turn rate to wheel into the attack _as a squadron_. As in all 12-16 aircraft with their guns blazing. This would generally force the German planes to break off. If the Germans kept trying to make these diving attacks, which they sometimes did, they would eventually drop down to an E state where the Allies could meet them on an equal basis, and then it was 'game on'. But it was a tense game, and the Allied pilots had to be very patient. Any deviation from this plan meant death.

The Allies also switched tactics so as to much more aggressively target Axis air bases. This often gave them a Tactical advantage because if the German fighters _didn't _enter into a sustained engagement, Allied fighter bombers or light bombers would smash up many of the Axis aircraft on the ground. If they _did_ enter into the sustained engagement, especially climbing up from below, they no longer had an advantage and usually took losses.

In the Pacific and China it could be a similar situation as the Zero and Ki-43 also had better altitude performance, but not by such a margin and they were slower than the P-40. They also had to fly at the altitude of the bombers and for tactical success the bombers often had to come in relatively low, so fighting often took place within the performance envelope of the P-40, and the P-40 in turn could usually (though not always) still escape an engagement with a high speed dive.

When the Japanese did relatively high altitude (22-25,000 ft) level bombing then the escorting Zeros had an advantage, and if the Allies came in with a bomb run at relatively low altitude the Japanese CAP often got the first attack, which is never good. The Japanese didn't seem to be quite as well organized as the Germans. RAF and RAAF pilots returning from the Western Desert noted how the pilots in the Pacific would chatter on the radio on the way to a target, whereas in Egypt they had to keep strict radio silence until engaged.

Ultimately the P-40 did very well in China, including long after the AVG was a memory, and did well in the Pacific, where their ultimate limitation proved to be range.

Also, the other big problem with the altitude limitation was that P-40s couldn't escort the big four-engined bombers unless the latter flew at low altitude, which limited their range and made them more vulnerable so it was usually never done in Europe. It was done in the Middle East sometimes and in the Pacific where there was less flak etc.

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## Schweik (Jul 18, 2020)

Acheron said:


> If the P-40 was truely mediocre all around, then I guess it boiled down to forcing the enemy into a way of combat where is plane was sub-par and avoid types of engagements where his was above the norm? Though that was true of pretty much every aircraft I would say, though some advantages (like speed) where easier to force onto te opponent than others (like maneuverability).



Also, in general, I think it's inaccurate to say that the P-40 was mediocre all around - it certainly had mediocre climb and altitude performance, and wasn't a gold medalist in all the key categories, but it was the best the Allies had in a few key areas (like dive) and kind of second or third best (silver or bronze medalist) in several categories. It was the fastest fighter in the Pacific Theater for a long time, and probably the most maneuverable Allied fighter in that region for the first year of the war. It was arguably the second most maneuverable monoplane fighter in the MTO and probably Russia too, due to it's combination of good roll and sharp turn rate. It was the best armed Allied fighter in Russia and the Pacific as well for a long time, and the fastest Allied fighter in the Western Desert at the altitudes they were usually fighting - at least until the P-38 arrived (and the early P-38s had all kinds of problems of their own). 

So maybe another way to look at it is grade point average. Other aircraft may have had an A two important categories (climb and altitude), a B in another (speed) and a few C's and D's (like range or high speed control), whereas the P-40 has one A, a lot of Bs with one D (effective altitude). In the end the grade point average was pretty high, higher than most.

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## Acheron (Jul 18, 2020)

@Schwik thank you, that was very illuminating. A question, I read that the Red Army didn't care much for the MiG-3, because while it had better high-altitude peformance than the Yaks and Las, this was simply rarely needed on the Eastern Front. Is this true and if so, what made the difference on the Eastern Front to other theaters of war?


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## Schweik (Jul 18, 2020)

It's true and in part it is because the MiG-3 had a very large and heavy engine, which didn't generate much power down low. So it wasn't so much that it was better at high altitude, it was also not very good at low altitude. Specifically it was way too slow down below 5,000 ft. It couldn't outrun or escape German fighters and sometimes couldn't catch German bombers either. The MiG-3 was also kind of twitchy even by the standard of Soviet aircraft at the time, and didn't turn too well, so without a speed advantage it was basically in trouble.

Most of the fighting on the Russian Front was at low altitude mainly because the combat was primarily Tactical, meaning in direct support of the ground fighting. The main part of the Soviet Air Force, the VVS, was the Frontal Aviation force, meaning the planes which fought right over the Front. The Germans did _some_ significant Strategic and Operational raids against the Russians particularly early in the war but they didn't have the kind of heavy high altitude bombers the US had and they too concentrated their efforts on the front line The most important German aircraft for the war-effort was the Stuka, which was a low altitude plane that dived down lower still to drop bombs (as a dive bomber). The longer ranged and higher flying Ju 88 was also used a lot in the dive bombing role, especially early in the war.

The most important Soviet aircraft conversely was the Il-2 attack plane, which was even more of a low altitude bird which came in strafing, shooting rockets and dropping bombs and bomblets. That is the weapon they used against German tanks and armored vehicles.

So in both cases, the fighters go where the bombers go. The other reason for the lower altitude combat was the weather. Something like 8 or 9 months out of the year depending which part of the gigantic front line you are talking about, there was often a fairly low cloud ceiling which prevented high flying planes from seeing the battlefield or lower flying aircraft.

The German fighters, particularly the Bf 109, were pretty good at both high and low altitude, though they were probably at their best up pretty high (~20' feet).

The Soviet fighters like the LaGG-3 and later La 5, the Yak -1, Yak -7, Yak -9 and later the Yak 3 were all basically low altitude fighters, best below 15,000 ft.

This was also true of the P-40s, P-39s and Hurricanes they got in pretty large numbers from the Anglo-Americans.

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## PAT303 (Jul 18, 2020)

Kevin J said:


> The P-40K should have been good for 344 mph at sea level and 364 mph from 5000 to 15000 feet,



Should have been or was?.


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## PAT303 (Jul 18, 2020)

Schweik said:


> the p-40 was not world's greatest in any particular category



The P40 and Spit MkV were equal in the sense of they were good enough to hold the line but not good enough to turn the tide, it took better aircraft to gain a decisive win in regards to gaining control of the air.


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## Schweik (Jul 18, 2020)

I don't think aircraft quality alone can do that. It's a combination of quality, numbers, tactics & logistics. The Me 262 was better than every Allied fighter in most respects, but it couldn't win the war.

For all their flaws, the Spit V, P-38 and P-40 F/L, along with a host of bombers & fighter bombers, had already turned the tide in the Med by the time the better fighters like the Spot IX and the P-47 arrived.

Because needless to say, as great as they were, the Bf 109, MC 202, and Fw 190 had flaws too


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## rochie (Jul 19, 2020)

soaringtractor said:


> Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!! The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!


terrible race us British, I'm almost ashamed

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## Just Schmidt (Jul 19, 2020)

soaringtractor said:


> Remember........ the P40 F used the Packard built V1650-1 merlin with the 2 speed supercharger and it did NOT perform as good as the Allison version did !!!! The shitfire Mk V and the P40 E matched up in time line, produced at about the same time and this proves why the Brits thought the P40 was the BEST AVAILABLE fighter of the time when they came to North American to see IF North American would build the {40 for them. It also would explain why 14,000 p40's were built in WWII and kept in production right to close to the end of the war. People, especially the brits like to bad mouth the Allison engine but mostly out of embarassment,as for its time it matched and exceeded the merlin in performance especially 20,000 ft and below. the only advantage the merlin 20 had was the second higher speed for the supercharger, realizing too the merlin was only slightly better above 20,000 ft. why the Merlin in the P40 F made NO performance gain over the merlin 20,000 ft and lower. Allison put out more power down low. and the Mustang Mk I & II was faster than the P40 !!!!! These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!



Evidently the Allison was the only ww2 vintage engine that could sustain multiple exclamation marks throughout a whole post. Must be due to its superior turbo-supermarker...

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## Kevin J (Jul 19, 2020)

rochie said:


> terrible race us British, I'm almost ashamed


I must agree about the Shitfire V bit though. Too little, too late.


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## rochie (Jul 19, 2020)

Kevin J said:


> I must agree about the Shitfire V bit though. Too little, too late.


For what ?


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## Kevin J (Jul 19, 2020)

rochie said:


> For what ?


Because it was outclassed by the Bf 109F.


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## PAT303 (Jul 19, 2020)

Kevin J said:


> Because it was outclassed by the Bf 109F.



They were like the Mk11 and Emil, one was better at some things, the other better at others, it wasn't until the MkIX came to being that there was a clear winner.


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## Kevin J (Jul 19, 2020)

PAT303 said:


> They were like the Mk11 and Emil, one was better at some things, the other better at others, it wasn't until the MkIX came to being that there was a clear winner.


Spitfire I/II combated Bf 109F-1/2 but inferior. Spitfire Vb/c combated Bf109F-4 but inferior. Spitfire IX outclassed Bf 109G.


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## Schweik (Jul 19, 2020)

Kevin J said:


> Spitfire I/II combated Bf 109F-1/2 but inferior. Spitfire Vb/c combated Bf109F-4 but inferior. Spitfire IX outclassed Bf 109G.



I think that gets exaggerated - keep in mind, Spit V was around for a long time and there were different subtypes with different configurations. The late model Vc matched up pretty well to a 109F-4, not in every respect but in enough of them to matter.


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## Schweik (Jul 19, 2020)

Spit Va or early b with 60 rounds per cannon and a weaker engine was vulnerable to a 109F but the Franz was around for a pretty long time too and the Spit kept being improved in little ways and there were different variants. The LF models with a Merlin 50M were quite fast down low & had the better roll rate.


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## Kevin J (Jul 19, 2020)

Schweik said:


> Spit Va or early b with 60 rounds per cannon and a weaker engine was vulnerable to a 109F but the Franz was around for a pretty long time too and the Spit kept being improved in little ways and there were different variants. The LF models with a Merlin 50M were quite fast down low & had the better roll rate.


The Spitfire Vb production models and Bf 109F-4 get introduced at the same time. By the time the Vc is introduced so is the Bf 109G-2. Its always the Vb compared against the F-2. This is not the correct comparison of versions. The Fw 190a is blamed for terminating the France Air Offensive. Its the Bf 109F that defeats the RAF in 1941.


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## Schweik (Jul 19, 2020)

well in the med it took a little while for the g's to get down there and they don't seem to have done a whole lot better anyway. Spit VC were fighting 109f4 and 109 g2 in 1942 and into 43 and they were not getting owned. There were different conditions in different theaters, I think the channel had its own unique challenges.


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## Schweik (Jul 19, 2020)

By 1943 it's G4's and maybe a few g6s. but my point was that if you look at that rather neglected but still quite important theater, by the time the spitfire Mark 9s get there the Germans have already been basically forced out of North Africa. The p-47 didn't arrive until they were already in Italy. The fighters that won that battle were basically the spit 5, the merlin p-40, and the p-38. older p-40s in hurricanes as well but as fighter bombers.


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## Kevin J (Jul 19, 2020)

Schweik said:


> By 1943 it's G4S and maybe a few g6s


The RAF was getting owned in both 1941 and 42 by the Luftwaffe.


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## Schweik (Jul 19, 2020)

I would say that in the med by the second half of 42 it had drawn even & by the end of 42 the raf was definitely winning.


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## Kevin J (Jul 19, 2020)

Schweik said:


> I would say that in the med by the second half of 42 it had drawn even & by the end of 42 the raf was definitely winning.


Yes, but through shear numbers.


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## SaparotRob (Jul 19, 2020)

Kevin J said:


> Yes, but through shear numbers.


A win is a win.

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## Schweik (Jul 19, 2020)

I think that shorthand is not quite right either. The DAF actually had more of a numerical advantage in 1941 & early 42 when they were losing. If you count the Italians the Axis were built up to.pretty close to numeric parity in fighters during the last 6 months before Tunisia fell. The Italians in particular were suffering from fuel shortages though.
A lot of the air battles were also fairly even because the Germans would concentrate their forces. I'll see if I can find some examples.

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## tomo pauk (Jul 19, 2020)

Schweik said:


> I think that shorthand is not quite right either.
> ...



What is a 'shorthand'?


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## Schweik (Jul 19, 2020)

That they won through sheer numbers that's what I mean by shorthand.

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## Schweik (Jul 19, 2020)

it's one of those historical soundbyte things that gets repeated to make it more manageable to tell the story but they're not always accurate


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## Schweik (Jul 19, 2020)

Ok so here is an example, took MAW II down from the shelf, first page I opened it up to 22 October 1942, almost smack in the middle of the book. It's a pretty good example.

DAF fighters escorted RAF medium bombers on several raids through the day.

First in the morning, 12 Kittyhawk Is from 4 SAAF Sqn escorted 18 Bostons on raids against Axis airfield in Daba, encountering Bf 109s from II. and III./JG 27
10:45 18 American B-25s were escorted by 6 x Kittyhawk Is from 450 Sqn RAAF, 10 x Kittyhawk Is from 3 RAAF and 10 from 260 RAF
11:00 Spit Vs from 145 Sqn, Kittyhawk IIIs from 112 Sqn, and P-40Fs from the US 66th FS (probably about 20 aircraft in total) flew a fighter sweep ('de-lousing') over daba. They were engaged by a total of 17 Bf 109s from II./JG 27, III./JG 53, and II./JG 27. 
12:15 another fighter sweep from nine Spits from 92 Sqn, 12 Kittyhawk IIas from 260 Sqn encounered Bf 109s from III./JG 27
11:00 15 x Macchi 202s from 9 and 10 Gruppi flew interception to engage the formation of Bostons.
11:35 11 x Macchi 202s from 4 Stormo, engaged Spitfires at 23,000 ft.
12:00 8 x Macchi 202s from 10 Gruppo engaged Spitfires
At an unstated point in the afternoon 238 Sqn RAF(Hurricanes) flew escort for a Tac-R mission.

*Allied forces making claims or taking losses:*
250 Sqn RAF (Kittyhawk III)
66 Fighter Sqn, 57th FG USAAF (P-40F)
145 Sqn RAF (Spit Vb)
260 Sqn RAF (Kittyhawk IIa)
450 Sqn RAAF (Kittyhawk III)
3 Sqn RAAF (Kittyhawk I)
601 Sqn RAF (Spit Vc)
92 Sqn RAF (Spit Vb and Vc)
238 Sqn RAF (Hurricane II)
4 SAAF Sqn (Kittyhawk I)

*Axis forces*
5./JG 27 (Bf 109F-4)
7./JG 27 (Bf 109F-4 trop)
8./JG 27 (Bf 109F-4)
Stab II./JG 27 (BF 109G-2 trop)
7./JG 53 (Bf 109F-4Z)
8./JG 53 (Bf 109F-4Z)
9./JG 53 (Bf 109F-4Z)
1./SchG 2 (Bf 109F-4)
4.(H)/12 (Bf 109F-4)

73 Sq 18 Gr 4 St (MC.202)
90 Sq 19 Gr 4 St (MC.202)
91 Sq 10 Gr 4 St (MC.202)
96 Sq 9 Gr 4 St (MC.202)
97 Sq 9 Gr 4 St (MC.202)

*Claims were *
DAF 7 X Bf 109 + probables and damaged
Axis 4 x P-40, 2 x P-46, 1 x B-25, 6 x Spitfires (the Italians claimed all the Spitfires) (12 fighters and 1 bomber)

*Actual losses were*
4 x Bf 109s shot down or crash landed after air combat, 2 x Bf 109s lost to Flak, 1 x MC 202 shot down, (5 fighters lost in air to air combat)
2 x Kittyhawk III, 2 x KIttyhawk I, 1 x Spit Vb, and 1 x B-25. Two Kittyhawk IIa were also badly damaged by 109s but landed at their own base (5 fighters +1 bomber lost).

Estimating the number of German and Allied fighters based on the number of units, all of which were lower than normal due to all the fighting, but the Germans had a bit fewer per squadron.

~ 40 -50 Bf 109 (mostly F-4 with a few G-2) and 34 MC 202 = Roughly 75 fighters
~ 25-30 Spit V, 30-35 Kittyhawk II or III, 15-20 Kittyhawk I, and 8-10 Hurricane II = Roughly 85 fighters

So as you can see, the odds were fairly even, as were the results. It's hard to say whether Kittyhawks or Spit V accounted for the enemy losses, but it wasn't extremely one sided. The Allies had a slight numerical advantage but roughly 30% of their forces, about 15 or 20 Kittyhawk I and 8-10 Hurricane II were definitely second string aircraft. Only the later model Kittyhawks and Spitfires could hold their own against the 109s - notice those were the ones sent on the 'de-lousing' missions.

Also worth pointing out, the 109s were almost all Franz.

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## Schweik (Jul 19, 2020)

I left out 112 Sqn RAF they were flying Kittyhawk III


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## GregP (Jul 19, 2020)

In the Reno Air Races a few years back (seems like 2010 or 2011), in the Bronze Final, a stock P-40 outran a stock F4U-1D. All he did was bump the rpm to 3200 and push a little extra MAP. The F4U-1D was running full bore and they were essentially side-by-side with the P-40 in front a bit for several laps. Just FYI.

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## Schweik (Jul 19, 2020)

Wow no kidding. That's actually kind of amazing. I wonder what specific type of 'stock' P-40 it was and what engine. I never heard much about war time pilots increasing RPM in the Anglo-American sphere but some of the Soviet pilots mentioned doing that, though they said it caused the engines to burn out quicker.

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## GregP (Jul 19, 2020)

There is a momentary toggle switch on the P-40 instrument panel. Once in constant-speed mode, if you push it upward, the rpm goes up by 200 and you release it and it returns to center. If you push it downward and release it, the rpm goes down by 200 rpm. On the day in question, the density altitude was probably above 6,500 feet and the P-40E was fast. 

It was essentially a stock P-40E that belongs to John Paul and was being flown by his son at the time. His machine is about as "stock" as it gets, and flies regularly.

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## MIflyer (Jul 19, 2020)

A key factor in the P-40's success in the Western Desert was numbers. They had sent Hurricanes in mere dribs and drabs to the Middle East but when the Hawk 81A Tomahawks arrived it was in squadron and wing strength. Those airplanes were not needed to defend the U.K. and they felt free to use them in numbers. The Germans in the theater were almost always heavily outnumbered after that. The Hurricane PR guys even went over to the new Tomahawk units and asked to coordinate their efforts to enable the P-40 fighter sweeps to give them some support.

When the Palm Sunday Massacure occurred they had four squadrons of USAAF Warhawks escorted by RAF Spitfires that attacked 90 Ju-52's escorted by BF-109's. They shot down 59 Ju-52's and 16 BF-109's while losing only 6 P-40's. The RAF escorting Spitfire losses were actually greater, I think. So there you have it. A overwhelming force of P-40's escorted by Spitfires did a great job - but the Warhawks had to be escorted by better air to air fighters for that to occur. I guess that is "learning how to use the airplane effectively."

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## Schweik (Jul 19, 2020)

Yeah but there are a few flaws with that argument. 

The "Palm Sunday Massacre" though not an unusual incident (there were at least half a dozen such wipeouts of German transports that took place by various types of fighters) it wasn't the typical P-40 mission in that Theater.

Many of the missions flown by those US P-40 units were beyond the range of the Spitfires. 

Typical mission flown was with P-40's flying top cover for older P-40's or Hurricanes, or for B-25's, Maryland's or Baltimore's. It's a myth that Spitfires always or even usually flew top cover for Kittyhawks.

Many of these missions were flown on days when Spitfires were not even flying. I broke this down for Oct 1942 on this forum. I'll find it & link it.

There was never a time when there were more P40's in Theater than Hurricanes. There were plenty of Hurricanes. They just couldn't be used in the same way.

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## Schweik (Jul 19, 2020)

Ok here is the post, it's all the combat data (via Mediterranian Air War) with claims and losses for both sides for October 1942, during the height of El Alemein. A couple of things are worth pointing out:

You'll notice that Spitfire units made claims on only 15 days during the month, whereas P-40 units of one type or another made claims on 25 days. Hurricane units made claims on 4 days. To me this is an indicator that A) P-40s were bearing the brunt of the fighting, and B) they were not being protected by Spitfires most of the time.

US P-40 units claimed 29 victories and lost 6 (3 shot down and 3 crash landed)
RAF P-40 units claimed 35.5 victories and lost 36 (about half were older model P-40s)
Spitfire units claimed 35 victories and lost 11 (10 shot down and 1 crash landed)
Total P-40 unit claims were 53.5, of which 32.5 were from late model P-40s (Kittyhawk II and II) and 11 were from early model (Kittyhawk I or Tomahawk).

Hurricanes IIc units claimed 12 (4 fighters and 8 bombers) and lost 19 (17 shot down and 2 crash landed)

The Germans themselves reported losing 11 fighters to P-40s, 2 shot down by Spitfires, and 1 shot down by a Hurricane. The rest did not indicate who got them.

*The Axis lost 81 aircraft *(62 shot down, 19 crash landed, of which 44/19 were fighters)
The Germans lost 41 x Bf 109s in total (34 shot down and 7 crash landed, of which 10 were G model, 28 were F model, and 3 were E model Jabos)
The Italians lost 18 MC 202s (10 shot down and 8 crash landed) plus 10 CR 42 fighter bombers (6 shot down and 4 crash landed).
The Germans also lost 15 bombers and 3 transports

T*he Anglo-Americans lost 90 aircraft *(73 shot down, 17 crash landed, of which 6 bombers were lost - of the fighters 39 P-40s were shot down and 14 crash landed)

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## Tkdog (Jul 19, 2020)

So, you’re going to go out and shoot down some Nazi transports. You have Spitfires and P-40s. Why would you not use them both? It’s a very high priority target and the fighters are there. At which point using them in a way that plays to to their strengths is fairly obvious. 

Too much time is spent on this plane is better than that plane. They were happy to have both of them and would have taken more of each. They figured out tactics for using them and they learned as they went. There really wasn’t a choice.

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## Schweik (Jul 20, 2020)

I agree with you generally, I do think however it's worth delving into the actual record sometimes to correct long standing myths and find out what actually happened. Ultimately, which aircraft is better is often meaningless, and is only decisive at the extremes. All military aircraft had their strengths and weaknesses. Looking at the performance of the pilots of Finland shows that tactics and training, and understanding the strengths and limitations of your own aircraft compared to those of your opponent can all matter more than the actual aircraft being used - at least to a point.

Part of where the human element came into play is where designers and engineers, military leaders, pilots and crew chiefs figured out how to push the limits to best exploit the strengths of the aircraft avialable to them, and the weaknesses of their opponents.

The region and conditions where combat takes place also matter a lot. Adapting to those conditions was another huge challenge. An aircraft which could bring victory in one Theater often struggled in another and vice versa.

And of course for those of us fascinated by WW 2 aircraft, it can be fun to delve into all of these complexities.

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## Schweik (Jul 20, 2020)

GregP said:


> There is a momentary toggle switch on the P-40 instrument panel. Once in constant-speed mode, if you push it upward, the rpm goes up by 200 and you release it and it returns to center. If you push it downward and release it, the rpm goes down by 200 rpm. On the day in question, the density altitude was probably above 6,500 feet and the P-40E was fast.
> 
> It was essentially a stock P-40E that belongs to John Paul and was being flown by his son at the time. His machine is about as "stock" as it gets, and flies regularly.



You might find this account interesting: Bf-109 vs P-40


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## Schweik (Jul 20, 2020)

MIflyer said:


> A key factor in the P-40's success in the Western Desert was numbers. They had sent Hurricanes in mere dribs and drabs to the Middle East but when the Hawk 81A Tomahawks arrived it was in squadron and wing strength. Those airplanes were not needed to defend the U.K. and they felt free to use them in numbers. The Germans in the theater were almost always heavily outnumbered after that. The Hurricane PR guys even went over to the new Tomahawk units and asked to coordinate their efforts to enable the P-40 fighter sweeps to give them some support.
> 
> When the Palm Sunday Massacure occurred they had four squadrons of USAAF Warhawks escorted by RAF Spitfires that attacked 90 Ju-52's escorted by BF-109's. They shot down 59 Ju-52's and 16 BF-109's while losing only 6 P-40's. The RAF escorting Spitfire losses were actually greater, I think. So there you have it. A overwhelming force of P-40's escorted by Spitfires did a great job - but the Warhawks had to be escorted by better air to air fighters for that to occur. I guess that is "learning how to use the airplane effectively."



So Operation Flax, of which the Palm Sunday massacre was part, took place in April 1943.


If you look at March 1943 you'll find (in Mediterranean Air War) that US P-40 fighter units engaged with and defeated German Bf 109 equipped units and Italian MC 202 and MC 205 equipped squadrons several times and got the better of them. On several specific occasions during March 1943 there were no other Allied aircraft involved. In some other cases there were Spitfires around but they claimed less aircraft shot down than the total number of Axis aircraft lost.
*23 March 1943 (USAAF 79 FG vs. JG 77 & JG 51) 2 Bf 109s lost to P-40's / 0 P40s lost
24 March 1943 (USAAF 33 FG vs. JG 77) 2 Bf 109s lost (+4 lost for 'unknown reasons')/ 1 P-40 lost
29 March 1943 (USAAF 33 FG vs. JG 77) 6 Bf 109 lost (4 destroyed +2 crash-landed) and 3 He 111's and 1 Ju 88 / 2 P-40's lost (1 to AA)
31 March 1943 (USAAF 33 FG vs. JG 77) 6 Bf 109 lost (3 destroyed +3 crash-landed) and Ju 87 lost to P-40 / 1 P-40 lost*

There was another similar spate of action in July 1943 in which US units were fighting Axis fighters beyond the range of the Spits on several days:

*July 8 1943 (US 324th FG vs. JG 77 and JG 53 and Italian 150 Gr CT) 5 x German Bf 109G-6 lost and 1 x Italian Bf 109G lost / 3 P-40s lost
July 22 1943 (US 325th FG vs. Italian 22 and 51 Stormo) 4 x MC 205 shot down, (+ 2 x 205 'shot up by P-40s') 3 x MC 202 & 1 X D.520 shot down , Ca 309 shot down / 2 x P40 lost
July 26 1943 (US 325th FG vs. JG 53 and Italian 51 Stormo) 2 x Bf 109G shot down, 1 x MC 205 (+1 205 'shot up by fighters') / 0 P-40s lost
July 30 1943 (US 325th FG vs. JG 77) 6 x Bf 109G Shot down***** / 1 P-40 shot down*


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## Vincenzo (Jul 20, 2020)

That the P-40 was successfull versus the 109 in MTO is a myth

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## PAT303 (Jul 20, 2020)

MIflyer said:


> A key factor in the P-40's success in the Western Desert was numbers.



I feel the problem the Bf109 had against the P 40 was the same problem the MkV had against the FW 190, they were medium/high level fighters that were used at the later two's low altitude.


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## MIflyer (Jul 20, 2020)

If the 56th had been flying Spit V and IX that day they would have scored even higher kills - assuming the Spits had enough fuel to hang around. They needed the Spits as top cover because the P-40 could not hack it. Some 109's made it down to try to get the P-40's off the JU-52's, no doubt tried to turn with a P-40, and got clobbered. The Spits scored far fewer kills, and none of the Ju-52's because they were totally engaged with keeping the 109's busy.

If that top cover had been P-40's instead of Spits the American losses would have been far greater and the kills far fewer, even though they had 40 to 60 fighters.


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## fubar57 (Jul 20, 2020)

This is from a 2011 book, "P-40 Warhawk vs Bf 109 MTO 1942 - 44" by Carl Molesworth...

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## Schweik (Jul 20, 2020)

fubar57 said:


> This is from a 2011 book, "P-40 Warhawk vs Bf 109 MTO 1942 - 44" by Carl Molesworth...
> 
> View attachment 589034
> 
> ...



I have the same book, it's a good one. But comparing those two lists is a little misleading for a couple of reasons -

The Allied Aces listed there only include the American pilots.
The Americans were only active in relatively small numbers and some only for a few months, compared to as much as 3 years for the Commonwealth pilots.
Those German Aces scored most of their victories against British or Commonwealth pilots flying older model planes
Many of their victories (for example of Marseilles) made claims for P-40s when they actually got Hurricanes.


Here is a partial list of Commonwealth Aces who flew the P-40 (there are 23 more):

*No / Name / Total / P-40 / Nation*
1 Neville Duke 27 UK (8-10 in KIttyhawk and Tomahawk)
2 Clive Caldwell 26 20 Aus
3 Billy Drake 24.5 13 UK
4 James Francis “Stocky” Edwards 19 12 Can
5 R J C Whittle 11 11 Aus
6 Keith Truscott 17 Aus
7 John Lloyd Waddy 15 11 Aus (first 12 kills in P-40, more in Spitfires)
8 Andrew “Nicky” Barr 12.5 Aus
9 Peter Turnbill 12 Aus (5 kills on P-40 in Med, 3 kills in Pacific)
10 Geoff Fiskin 11 NZ
11 Bobby Gibbes 10.5 Aus
12 N Bowker 10 9 UK
13 D W Golding 8 8 SA
14 E C Saville 8 8  SA
15 J E Frost 14 7 SA
16 M S Hards 7 7 UK
17 A C Bosman 8 6 SA
18 A C Cameron 6 6 Aus
19 O V Hanbury 10 6 UK
20 R M Leu 6 6 UK
21 Wilfred Arthur 10 Aus (4 kills in one sortie in Med, also fought in
Pacific)

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## Schweik (Jul 20, 2020)

MIflyer said:


> If the 56th had been flying Spit V and IX that day they would have scored even higher kills - assuming the Spits had enough fuel to hang around. They needed the Spits as top cover because the P-40 could not hack it. Some 109's made it down to try to get the P-40's off the JU-52's, no doubt tried to turn with a P-40, and got clobbered. The Spits scored far fewer kills, and none of the Ju-52's because they were totally engaged with keeping the 109's busy.
> 
> If that top cover had been P-40's instead of Spits the American losses would have been far greater and the kills far fewer, even though they had 40 to 60 fighters.



I don't know what you base that on, since I've pointed out something like 10 days of battle where the P-40s were flying top cover, as they usually were, no Spitfires were in the battle area, and yet they shot down far more German planes than they lost.

For some people it's an article of faith.


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## Schweik (Jul 20, 2020)

Vincenzo said:


> That the P-40 was successfull versus the 109 in MTO is a myth



Again, that sounds more like the voice of faith than based on any actual data.

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## Schweik (Jul 20, 2020)

Circling back to the Spitfire for a moment, I would put it like this.

The original very broad Spitfire legend is that it dominated the Bf 109 and won the Battle of Britain. When we drill down a little deeper into the data we find that the early Spit (I and II) was pretty evenly matched with the 109E, but that the 109 suffered a bit more from the Tactical situation of having to fly escort (and sometimes ill conceived close escort) and often near the limits of their operational range, as well as going against an integrated air defense with radar. We also know that Hurricanes shot down most of the German bombers.

Then the Spit V and Bf 109F arrived, with the Fw 190 not long after, and once again the conventional wisdom was that the Spit V was inferior.

The Franz was a major improvement over the Emil. It was far better streamlined, had a significantly more powerful engine, had more ammunition and (arguably) more accurate guns. From what I understand they got the leading edge slats working properly in the F model.

The Spit V was also a big leap forward but it was initially plagued with a number of minor flaws and issues. The guns were prone to jamming and the cannons only had 60 rounds each, and they could sometimes freeze at high altitude. The carb would still flood with a negative G push-over. The Merlin 45 engine though more powerful than the Merlin II or III on the Spit Mk I, was not up to it's full potential. And in the Med they had a lot of problems with the Tropical filters.






When the British started trying to fly provocation raids over the Channel, they were reversing roles and were now the ones facing an integrated air defense. This was a big part of the problem. But initially it's clear the _early_ Spit V was inferior to the 190 and a bit so compared to the 109F-2

But the Bf 109F and the Spit were both around for a long time. The Franz came out in 1941 but it was still being used at least in the Med all through 1942 and even in 1943. The Spit V lasted even longer, still equipping some units in 1944.

The F went basically from the F-2 to the F-4, improving from a 15mm cannon to a much more deadly 20mm. They improved the engine power by about 100-150 hp.






But the Spit V improved even more. They got the 130 octane fuel and increased the allowed boost, and put in engines with more horsepower - it went from ~ 1,200 hp to routinely up to 1,585 at high boost. Rate of climb and acceleration improved. Dive was faster because there was no carb cutout with the Bendix carb. They fixed most of the problems with the air filter. They replaced the drum based cannon with belt fed cannon that gave twice as much ammunition and reduced the tendency to jam. They improved heating systems to keep the guns from freezing. They made specialized LF and HF versions. And they improved their tactics - it took a while to start using the finger four / pairs system in the MTO for whatever reason, even though it was already done in the BoB, but once they were doing that and a lot of other things in the Med, it made a difference. They got better and more reliable radios.











A Spitfire LF Mk Vc with a Merlin 50 or 50M, (let alone a 55M though those came later) was a pretty dangerous aircraft and definitely could hold it's own anything the Axis had in the MTO Theater. The IX was still better, but the late model Vc was clearly on par with an MC 202 or the 109F-4 and didn't seem too bothered going up against a 109G-2 or G-4 either.






I would argue that the P-40 history in the Med was kind of similar. The Tomahawk arrived and brought success to the DAF. It was dominant over the G.50, MC 200 and Bf 110, and could hold it's own with the 109E. It's arrival hurried the replacement of the 109E with the F. The F was superior to the early P-40s (both Tomahawk and Kittyhawk) and took a heavy toll from winter of 41/42 through the first few months of 42. The early Kittyhawk had a 1,050 hp engine and many of the same problems as the Spit - wing guns jamming, engine running below full potential, bad tactics and so on.






But the British, Australians, South Africans and Americans flying the P-40 got the new high octane gas and started increasing the boost. They adopted pairs and formation tactics. Curtiss made improvements to the guns which reduced jamming, and lengthened the fuselage to improve high speed stability. The newer V-1710-73 Allison Engines could go up to 1550+ HP down low, and the V-1650 Packard-Merlin engined variants were good for 1,350-1,400 hp and raised the performance ceiling by 8,000 ft. That is when the tide started to change with those units as well.

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## buffnut453 (Jul 20, 2020)

Schweik said:


> I have the same book, it's a good one. But comparing those two lists is a little misleading for a couple of reasons -
> 
> The Allied Aces listed there only include the American pilots.
> The Americans were only active in relatively small numbers and some only for a few months, compared to as much as 3 years for the Commonwealth pilots.
> ...



Minor nitpick but Fisken only had 5 kills while flying P-40s.

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## Schweik (Jul 20, 2020)

buffnut453 said:


> Minor nitpick but Fisken only had 5 kills while flying P-40s.



Thanks I'll adjust my notes on that. I think he got several with the Buffalo too.


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## Schweik (Jul 20, 2020)

Does anyone know when the Spitfire got constant speed props?


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## Greyman (Jul 20, 2020)

Roughly June / July 1940.


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## PAT303 (Jul 20, 2020)

All front line Spitfires got a field modification involving fitting De Havilland CS props starting in June 1940, the Rotol CS prop had bee fitted since 1939 but required changes to the Merlin to fit it so limited it's use.

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## Reluctant Poster (Jul 20, 2020)

Schweik said:


> Circling back to the Spitfire for a moment, I would put it like this.
> 
> The original very broad Spitfire legend is that it dominated the Bf 109 and won the Battle of Britain. When we drill down a little deeper into the data we find that the early Spit (I and II) was pretty evenly matched with the 109E, but that the 109 suffered a bit more from the Tactical situation of having to fly escort (and sometimes ill conceived close escort) and often near the limits of their operational range, as well as going against an integrated air defense with radar. We also know that Hurricanes shot down most of the German bombers.
> 
> ...


The Spitfire V never had a Bendix carb


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## Schweik (Jul 20, 2020)

Merlin 50 & 55 did I believe


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## Reluctant Poster (Jul 20, 2020)

Schweik said:


> Merlin 50 & 55 did I believe


They did not. 
Merlin 50 Diaphram type carburetor. Rolls Royce developed.
Merlin 55 R.A.E. Anti g type carburetor 
Both of these were modified SU carburetors. The diaphragm feed was abandoned in favour of the R.A.E. modification. To quote Lumsden: “These trials resulted in a retrospective modification on all Merlins fitted with S.U. carburettors.”
Rolls Royce Piston Aero Engines - a designer remembers figures 90 and 91 illustrate the SU carburetor and the SU carburetor with anti g modification developed in conjunction with RAE Farnborough respectively.


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## Shortround6 (Jul 20, 2020)

Schweik said:


> We also know that Hurricanes shot down most of the German bombers.


Well, there were a lot more Hurricanes in service so that did tend to affect the scoreboard. 



Schweik said:


> The Merlin 45 engine though more powerful than the Merlin II or III on the Spit Mk I, was not up to it's full potential.


In part due to the Fuel and in part due to the fact that the MK V and it's engines were in production for along time, Mk Vs first show up in the Spring of 1941 and the last are built in the summer of 1943(?). The P-40 didn't stand still either. The first P-40D being delivered May 7th 1941 and by the summer of 1943 Curtiss was building P-40N-5s. 



Schweik said:


> The early Kittyhawk had a 1,050 hp engine


Typo? 1150hp? 



Schweik said:


> But the Spit V improved even more. They got the 130 octane fuel and increased the allowed boost, and put in engines with more horsepower - it went from ~ 1,200 hp to routinely up to 1,585 at high boost.


The 1585hp engines were the ones with the cropped impellers. the 1585hp was at 2750ft (no ram) at 18lbs boost. The standard Merlin 45s were eventually approved for 16lbs boost and either 1515hp at 11,000ft or 1470hp at 9250 depending on exact model and carburetor. The 1200hp figure was at a bit above 18,000ft. 
Question on the Spit MK V is when the units in the field went from 9lbs boost to 12lbs and then when they changed from 12 to 15/16lbs boost. 
I don't know if the cropped impeller was an interim solution. As in if it was allowed higher boost first and then the full size impeller engines were allowed to use the high boost later? 

The cropped impeller engines made 45hp more for take-off at 3000rpm and 12lbs boost than the full size impeller engines.

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## Schweik (Jul 20, 2020)

Reluctant Poster said:


> They did not.
> Merlin 50 Diaphram type carburetor. Rolls Royce developed.
> Merlin 55 R.A.E. Anti g type carburetor
> Both of these were modified SU carburetors. The diaphragm feed was abandoned in favour of the R.A.E. modification. To quote Lumsden: “These trials resulted in a retrospective modification on all Merlins fitted with S.U. carburettors.”
> Rolls Royce Piston Aero Engines - a designer remembers figures 90 and 91 illustrate the SU carburetor and the SU carburetor with anti g modification developed in conjunction with RAE Farnborough respectively.



Ok I'm going by Wikipedia which is always a little risky. It says:

Merlin 50 - *Merlin 50* series was first to use the Bendix Stromberg "negative-g" carburettor.[10][18][19] 

Their first source is this which says: "*Merlin 50 series */ Similar to Merlin 45. Majority of production engines *fitted with anti-G carburettor*."
Their second source is this book - but I can't read what it says because it's behind a paywall.
Their third source is this which says "The only difference between a Merlin 45 and 50 *is the fitting of a "negative g" carburettor *and a fuel de-aerator on the latter engine, and these are unlikely to have a marked effect on performance. "


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## Schweik (Jul 20, 2020)

Shortround6 said:


> Well, there were a lot more Hurricanes in service so that did tend to affect the scoreboard.
> 
> 
> In part due to the Fuel and in part due to the fact that the MK V and it's engines were in production for along time, Mk Vs first show up in the Spring of 1941 and the last are built in the summer of 1943(?). The P-40 didn't stand still either. The first P-40D being delivered May 7th 1941 and by the summer of 1943 Curtiss was building P-40N-5s.
> ...



You are right, I transposed the number from the Tomahawk which was 1040 for takeoff. The V-1710-39 on the P-40D / E was initially rated for 1,150 hp at 42" Hg, then this was changed (I think in April 1942) to 1,240 hp for takeoff at 45.5" Hg (5 minute rating) and then later around June or July 1942 (probably with the newer engines with the strengthened cam shaft etc.) bumped up to 1,470 hp at 56" Hg (5 minute rating).

The V-1710-73 on the P-40K was 1,325 hp at 51" Hg for takeoff and 1,550 hp at 60" Hg WEP (5 minutes at Sea Level) with military power back down to the 1,150 hp rating at 42"



> The 1585hp engines were the ones with the cropped impellers. the 1585hp was at 2750ft (no ram) at 18lbs boost. The standard Merlin 45s were eventually approved for 16lbs boost and either 1515hp at 11,000ft or 1470hp at 9250 depending on exact model and carburetor. The 1200hp figure was at a bit above 18,000ft.
> Question on the Spit MK V is when the units in the field went from 9lbs boost to 12lbs and then when they changed from 12 to 15/16lbs boost.
> I don't know if the cropped impeller was an interim solution. As in if it was allowed higher boost first and then the full size impeller engines were allowed to use the high boost later?
> 
> The cropped impeller engines made 45hp more for take-off at 3000rpm and 12lbs boost than the full size impeller engines.



There are a couple of references to the LF types in MAW, with kind of a hint that they were 'hot', but they usually don't specify that much detail, typically they just say Spit Vb or Vc or sometimes they only say Spit V

Do you know the answer about the pressurized carb?


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## Shortround6 (Jul 20, 2020)

The Book "The Merlin in Perspective" by Alec Harvey-Bailey lists the different carbs used on Merlin engines but gives model number. No way of knowing if one of the later ones is a Bendix _type _under a different name or licence

However.
Merlin 45................A.V.T. 40/193 or 214 carburetter. 
Merlin 45M............same with stronger boost control spring. Mod 615
Merlin 46................same with larger chokes.
Merlin 47...............same as Merlin 46
Merlin 50...............A.V.T. 40/ 214 carburetter
Merlin 50M..........same with stronger boost control spring. Mod 615
Merlin 55..............A.V.T. 40/ 216 carburetter
Merlin 55M..........as Merlin 55.

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## Schweik (Jul 20, 2020)

I couldn't find anything under "A.V.T. 40/ 214 carburetter" or _carburetor_


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## Shortround6 (Jul 20, 2020)

Using the spelling in the book


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## Schweik (Jul 21, 2020)

I figured... never seen that one though


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## Schweik (Jul 21, 2020)

Anyway do you agree or disagree with my contention that the 1943 Spit V was far more formidable than a 1941 Spit V?

Whether or not it was an LF variant is a secondary factor, it could be good if fighting low as was often the case in N/A, and the LF had that dynamite roll rate, but it may be giving up the altitude advantage to the Luftwaffe. Presumably you could use both types though.

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## buffnut453 (Jul 21, 2020)

Schweik said:


> Thanks I'll adjust my notes on that. I think he got several with the Buffalo too.



All his other kills (6 in total) were in the Buffalo.

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## PAT303 (Jul 21, 2020)

Shortround6 said:


> Question on the Spit MK V is when the units in the field went from 9lbs boost to 12lbs and then when they changed from 12 to 15/16lbs boost.


Merlin 45's were cleared for 16psi boost @3,000rpm in July '42, 18psi in Feb '43, MkV LF's with Merlin 50's 18psi boost @ 3,000rpm May '43.

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## PAT303 (Jul 21, 2020)

Schweik said:


> Anyway do you agree or disagree with my contention that the 1943 Spit V was far more formidable than a 1941 Spit V?



Against the FW190 the '41 version was outclassed, by '43 the Anton pilot needed to have is brain in gear, what made his job even worse was the Mk IX looked the same except for being 9'' longer, and both had reliable belt fed Hispano's loaded with SAPI rounds.

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## wuzak (Jul 21, 2020)

PAT303 said:


> Against the FW190 the '41 version was outclassed, by '43 the Anton pilot needed to have is brain in gear, what made his job even worse was the Mk IX looked the same except for being 9'' longer, and both had reliable belt fed Hispano's loaded with SAPI rounds.



And there was also the Mk XII in 1943. Also looking similar to the V, at least from a distance.

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## Reluctant Poster (Jul 21, 2020)

Schweik said:


> I couldn't find anything under "A.V.T. 40/ 214 carburetter" or _carburetor_


Once again I point to Figure 91 of Rolls Royce Piston Aero Engine by A A Rubbra. it is a “TYPE AVT 40 ANTI-g”. It is an “SU carburettor with anti-G modification developed in conjunction with R.A.E. Farnborough.”
From the same book: “To deal with this problem a negative ”G” carburettor was designed which provided a diaphragm controlled fuel supply to the carburettor as a replacement for the normal float and needle. This proved unsuccessful in service trials and an anti “G” version of the S.U. carburettor (91) was developed, with modified valving in the float chamber. This worked satisfactorily and was in use to the end of the war on both single and two stage engines.”
In references you provided the only mention of Bendix is the Wiki article. Ant -g does NOT automatically mean Bendix.

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## Schweik (Jul 21, 2020)

As long as it works in negative G it's basically the same outcome right?


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## Reluctant Poster (Jul 21, 2020)

Schweik said:


> As long as it works in negative G it's basically the same outcome right?


I really don’t care if it had warp drive all I care about is that it wasn’t a Bendix

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## MIflyer (Jul 21, 2020)

The negative G problem with the Merlin featured a "Lean Cutout" and a "Rich Cutout."

When the nose was shoved over the fuel in the carb float chamber rose to the top, and therefore could not be sucked into the engine. This was fixed by putting a standpipe in the float chamber giving a path for the engine to inhale the fuel from the top of the float chamber.

After positive G was regained the float chamber had become full of fuel during the negative G period, resulting in an excessively rich mixture and another loss of power, typically evidenced by a burst of black smoke coming out of the exhaust. This was fixed by putting an orifice in the fuel line that limited the amount of fuel that could get into the float chamber.

In contrast, the Bendix Pressure Carb commonly used on US high power engines was completely different and injected fuel into the center of the mechanical supercharger inlet so it was a form of "Throttle Body Injection" and was immune to the G load situation. The British eventually adopted the Bendix carb, seen below on a V-3420.

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## Reluctant Poster (Jul 21, 2020)

Reluctant Poster said:


> I really don’t care if it had warp drive all I care about is that it wasn’t a Bendix


I should apologize. That answer was flippant When I see an error I have to correct it, it is my nature.
I do agree that the SU negative problems were solved and that the later Spitfire Vs were much improved. In fact the Seafire III powered by the Merlin 55 was fully competitive to the end of the war.

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## Schweik (Jul 21, 2020)

Reluctant Poster said:


> I really don’t care if it had warp drive all I care about is that it wasn’t a Bendix



All I care about is did it work.


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## Schweik (Jul 21, 2020)

PAT303 said:


> Against the FW190 the '41 version was outclassed, by '43 the Anton pilot needed to have is brain in gear, what made his job even worse was the Mk IX looked the same except for being 9'' longer, and both had reliable belt fed Hispano's loaded with SAPI rounds.



At 1,500+ HP down low and clipped wings for a superlative roll rate + less drag, Spit LF Mk Vc is pretty dangerous for a 190 I think.

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## Schweik (Jul 21, 2020)

Also going to the belt fed guns meant smaller bulges on the wings which was also less drag


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## Greyman (Jul 21, 2020)

The belt-fed Hispano Spitfire actually heralded the larger bulges of the 'C' wing that were to accommodate the four-cannon option.

Later when it was decided the four-cannon wing was essentially never used -- covers with smaller bulges were manufactured. But to your point I do believe these '43/44 panels were smaller than even the initial '41 panels.

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## Clayton Magnet (Jul 21, 2020)

Schweik said:


> The Spit V was also a big leap forward


Was it though? The Mk.V was the definitive low point of the Spitfires career, with the Australian Mk.V's (Merlin 46, hastily fit tropical filters, malfunctioning cannons) experience over Darwin being the bottom.
I love the Spitfire, but that configuration seems like almost a worst case scenario.

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## Schweik (Jul 21, 2020)

Clayton Magnet said:


> Was it though? The Mk.V was the definitive low point of the Spitfires career, with the Australian Mk.V's (Merlin 46, hastily fit tropical filters, malfunctioning cannons) experience over Darwin being the bottom.
> I love the Spitfire, but that configuration seems like almost a worst case scenario.



They had trouble in Russia too with the Spit V. Clearly it made a bad first impression.

But yeah this is how i see it. Putting cannons in the Spit was a fairly big engineering leap, as was the new engine (IMO). But any time you make significant changes you have an adjustment period. Spit V was kind of rushed into action before the shakeout was done (because it had to be) - and at the end of a very long supply chain all problems get exaggerated. Same thing happened incidentally with the early P-40s, especially the P-40E. They had trouble in the Philippines and Java just getting them flying. The Australians lost like twice as many getting their first batch of Kittyhawks into the combat area as they did in action. There are a lot of little details that have to be sorted out - like what throttle setting to use in combat!

However, as noted, the Spit V was around for a long time. Clearly at some point it became rather more dangerous and effective. I think the big threshold was when the guns became more reliable. In MAW you can see that initially the Spitfire units were maybe suffering a bit but by the end of 1942 it seems like they had sorted a few things out and were taking a toll. As were the later model Kittyhawks.

Darwin was a bit later than that but it was 13,000 km from London. A lot can go wrong across that distance, and did.


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## Juha3 (Jul 21, 2020)

Schweik said:


> They had trouble in Russia too with the Spit V. Clearly it made a bad first impression...



Soviets had their problems but their experiences were not entirely negative. I'm busy now, so only a quote from _Spitfires over the Kuban_ by Igor Zlobin © Tranlsation by James F. Gebhardt ©
(the numbers are showing how the Soviets saw the results, and remember that most Soviets really liked P-39s, 3 of their 5 top scorers got most of their kills while flying Airacobras)

*Table 1. Combat work of the 216th SAD from 1–10 May 1943*​
Regiment-------Number of aerial---Downed enemy-----Damaged enemy------Soviet losses
-------------------engagements--------aircraft---------------aircraft--------------Destroyed---Aircraft did not---Pilots
---------------------------------------(bombers + fighters)-------------------------aircraft----------return
16 GIAP (P-39)----20-------------------24-(8 + 16)-----------9------------------------1----------------2-------------3
57 GIAP (Spitfire)-23-------------------30-(15 + 15)---------10------------------------4----------------3-------------3
42 GIAP (Yak-1)----2--------------------1----------------------------------------------------------------1--------------1

​

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## Schweik (Jul 21, 2020)

I read the article Spitfires over the Kuban, and I agree it wasn't an unmitigated disaster but nor was it the rousing success they were expecting. Also I think different P-39 units in various regions had rather wildly different rates of success if I remember correctly. 

I wouldn't say the Spit V was more successful for the Russians than the Kittyhawk was.


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## Reluctant Poster (Jul 21, 2020)

Schweik said:


> I read the article Spitfires over the Kuban, and I agree it wasn't an unmitigated disaster but nor was it the rousing success they were expecting. Also I think different P-39 units in various regions had rather wildly different rates of success if I remember correctly.
> 
> I wouldn't say the Spit V was more successful for the Russians than the Kittyhawk was.


The Spitfires were refurbished Vb‘s and they had the higher altitude 46 where a cropped 45 would have been more appropriate

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## Clayton Magnet (Jul 21, 2020)

Schweik said:


> However, as noted, the Spit V was around for a long time. Clearly at some point it became rather more dangerous and effective


The Mk.V started life a half step behind to begin with. Perhaps in hindsight it was the best available decision to develop the model minus the Merlin XX, but it is more romantic to imagine the Fw 190 like performing Mk.III following the Mk.II into service in 1941.


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## Kevin J (Jul 21, 2020)

Clayton Magnet said:


> The Mk.V started life a half step behind to begin with. Perhaps in hindsight it was the best available decision to develop the model minus the Merlin XX, but it is more romantic to imagine the Fw 190 like performing Mk.III following the Mk.II into service in 1941.


End 1940 we're expecting a German invasion in 1941, we don't know about the Bf 109F nor the Fw 190a. So we needs lots of fast climbing interceptors fast ready for a Summer invasion. The Spitfire Vb means we don't have to change the production lines. It's a quick fix.

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## Mike Williams (Jul 21, 2020)

Shortround6 said:


> The standard Merlin 45s were eventually approved for 16lbs boost and either 1515hp at 11,000ft or 1470hp at 9250 depending on exact model and carburetor. The 1200hp figure was at a bit above 18,000ft.
> 
> Question on the Spit MK V is when the units in the field went from 9lbs boost to 12lbs and then when they changed from 12 to 15/16lbs boost.


+12 was cleared for take-off from the get go on the Merlin 45. Rating of Merlin RM5S (Merlin 45), January 1941:




Spitfire V Type sheet from July 1941:



Merlin XLV - Operational Limitations, July 1941:

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## Juha3 (Jul 21, 2020)

Reluctant Poster said:


> The Spitfires were refurbished Vb‘s and they had the higher altitude 46 where a cropped 45 would have been more appropriate



At least with 57 GIAP their Spit Vbs were powered by both Merlin 45s and 46s. That most Spit Vbs sent to the USSR had Merlin 46s maybe was one of the main reasons why they ended up serving with the PVO, that also solved the problems related to poor airfield surfaces.

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## Mike Williams (Jul 21, 2020)

This document shows that +16 was approved by January 1942, whereas this report dated Nov. 42 and based on testing taking place from July - Sept. 42 notes "The operational limitations of the Merlin 45 have been increased, the use of 3000 R.P.M. and +16 lb/sq.in. boost being now permitted for periods not exceeding 3 minutes during combat."

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## Vincenzo (Jul 21, 2020)

i suspect that this http://www.wwiiaircraftperformance.org/merlin-ratings_3jan42.jpg is from 3rd january '43


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## Reluctant Poster (Jul 21, 2020)

Vincenzo said:


> i suspect that this http://www.wwiiaircraftperformance.org/merlin-ratings_3jan42.jpg is from 3rd january '43


I don’t believe so. It states the Merlin 61 is for production in summer 1942.
also it lists the Merlin 30 by 1943 it was replaced by the 32

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## Mike Williams (Jul 21, 2020)

Interestingly this chart for the Merlin 46 & 47 dated 27 March 1942 shows the +12 take off rating as well as the +16 Emergency rating.






These un-dated Operational Notes for Pilots on Merlin 46 Engines show the +12 take-off and climb rating.


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## Shortround6 (Jul 21, 2020)

So we basically have Spitfire MK Vs with 3 different armament setups, A number of different engines even if most of them were operated at the same performance levels if allowed to use the same boost. and we can throw in two different wing tips (but only on later Vbs and Vcs, late 1942?) 

The P-40*E* has no change in armament, two possible engines (pre and post Dec 1941) and possible different max boost allowances based on engine (date of manufacture).This last is conjecture on my part, in any case the P-40K took over from the P-40E on the production lines in May of 1942. 

Please note that it took months to get US fighters to the war zones. In some cases US fighters, like some/many P-40s, went to British modification centers before being shipped on to final destinations/war zones so first planes out the factory door are months away from first combat. 
The first modification center was at the _Tomahawk _school at Cunliffe-Owen Aircraft which by Nov 1941 was responsible for repairs to RAF Tomahawks, Bristol Blenheims and Lockheed Hudsons. The Kittyhawks were added. 
Scottish Aviation at Prestwick also assembled and modified many Kittyhawks and another modification (assembly) center was Air Service Training Center Hamble near Southampton which also worked on early P-39s and Mustangs. 

My conjecture comes from Allison changing the crankshaft in the Allison engines in Dec of 1941. The new crankshaft was stronger and much more fatigue resistant. This is what allowed the engines in the P-40Ks to be rated at 1325hp for take-off. I believe that many late build P-40Es may have had these crankshafts. 
I don't doubt that the older engines (all -39 engines) could be run at the high boost settings, the question might be for how long or how many times? 
Official US approval for WEP settings was around 3/4 of a year after the change in the crankshafts?

NA had built about 138 Mustangs for the British in 1941 and another 84 in both Jan and Feb so how long it took the better crankshafts to work their way through the supply chain and into the Mustang Is I have no idea. 


We really have to be careful as to which Spitfire V we are comparing the P-40*E *or later versions of the P-40.


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## Shortround6 (Jul 21, 2020)

Mike Williams said:


> Interestingly this chart for the Merlin 46 & 47 dated 27 March 1942 shows the +12 take off rating as well as the +16 Emergency rating.
> 
> View attachment 589238
> 
> ...




It's a mystery as to why the Australians were operating the Melrin 46s at a 9lb boost limit at the time of the test.


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## Schweik (Jul 21, 2020)

Shortround6 said:


> So we basically have Spitfire MK Vs with 3 different armament setups, A number of different engines even if most of them were operated at the same performance levels if allowed to use the same boost. and we can throw in two different wing tips (but only on later Vbs and Vcs, late 1942?)
> 
> The P-40*E* has no change in armament, two possible engines (pre and post Dec 1941) and possible different max boost allowances based on engine (date of manufacture).This last is conjecture on my part, in any case the P-40K took over from the P-40E on the production lines in May of 1942.



The P-40E (Kittyhawk 1A) was basically a slightly modified *P-40D* (Kittyhawk I), of which 600 made, which was basically only in use by the British who got about 560 of them between April and September of 1941. The US got about 40 and deverted maybe of those 20 to Canada. They were in action with the DAF in Egypt by January 1942. The P-40D represetned the big change from the P-40B and C by shortening the nose and putting the big guns in the wing. The early P-40Ds had two guns in each wing, but probably most of them had the traditional three guns in each wing like the P-40E. They were plumbed for an external fuel tank or a bomb on the centerline.

There were 2500 *P-40E */ Kittyhawk IA built, with most of them (about 1,500) again going to the British, a few hundred were sent to Java and the Philippines shortly before being destroyed largely on the ground by the IJA and IJN, as well as about 300 which arrived too late so were diverted into the hands of the Australians* (but some of those sank in their crates inside transport ships on the way). A (to me) unknown number were sent to New Zealand, but probably no more than 100, and another 300 or so to the 23rd FG (former AVG) in China. The British also sent probably a couple of hundred to the Russians though some of those only after they had been used (and a little worn out) in the Middle East. They originally had the same engine (V-1710-39) as the P-40D but some were actually re-engined in the field or at maintenance depots with the V-1710-73, though that may have only been done in Australia / New Guinea. Later run P-40E had two wing hard points and the centerline external fuel tank /r bomb hard point. They were able to carry up to three 250 lb bombs or more rarely, two 500 lb bombs for short hops. About halfway through the production run they changed the method of ammunition storage which reduced stoppages during high G maneuvers.

The last variant in this closely related sub group is arguably the* P-40K */ Kittyhawk III - About 1,300 were made. 600 were sent to China (most ending up with the 23 FG but some also with CATF). 192 were sent to England with most of those ending up in the Middle East. 42 were sent to Australia, 22 to New Zealand and 25 were given or sold to Brazil, with most of the remaining 400 or so going to various units in the Pacific, and a few dozen being used briefly by the 57th FG in the MTO. At least 110 were sent to Russia from the US, possibly the British sent some of theirs as well. The K had a different ("rotary valve") cooling system and was given first a fin, then a lengthened tail (by 20") to improve stability. They had some kind of improved exhaust stacks. They used a different version of the M2 browning and like the late run E model had a different method of ammunition storage which reduced stoppages during high G maneuvers. They could routinely carry three 500 lb bombs and on occasion carried two 1,000 lb bombs for short missions.



> My conjecture comes from Allison changing the crankshaft in the Allison engines in Dec of 1941. The new crankshaft was stronger and much more fatigue resistant. This is what allowed the engines in the P-40Ks to be rated at 1325hp for take-off. I believe that many late build P-40Es may have had these crankshafts.
> 
> I don't doubt that the older engines (all -39 engines) could be run at the high boost settings, the question might be for how long or how many times?
> Official US approval for WEP settings was around 3/4 of a year after the change in the crankshafts?



Apparently in Australia they fitted several P-40E with V-1710-73

Allison also sent replacement engines which were probably midway in performance / toughness between -39 and -73. As you know there were at least two different modifications made to the crank shaft and they also made a change to the crank case and some other parts.

The official approval for the change in boost was lagging behind field conditions, but those were by British / Commonwealth units anyway for the most part over whom USAAF policies didn't matter so much. No US units flew P-40D or E in the Med. The need for overboosting wasn't as urgent in the Pacific though they did it there too of course (as noted in the infamous Allison memo).

* the Australians promptly lost about half of these during training accidents and in landing accidents while ferrying them in several flights from Southern Australia to the Darwin area and then Port Morseby.

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## PAT303 (Jul 22, 2020)

Clayton Magnet said:


> Was it though? The Mk.V was the definitive low point of the Spitfires career, with the Australian Mk.V's (Merlin 46, hastily fit tropical filters, malfunctioning cannons) experience over Darwin being the bottom.
> I love the Spitfire, but that configuration seems like almost a worst case scenario.



Have to agree with this, the '41 era MkV's didn't really offer anything over the Mk11 to be honest, the Mk111 on the other hand would have been the best fighter in the world bar none if it was adopted. Likewise the Australian MkV's were a whole new misery, low boost engines in worn out air frames flown by novice pilots using outdated tactics, they were lucky the Japanese gave up.


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## PAT303 (Jul 22, 2020)

Shortround6 said:


> It's a mystery as to why the Australians were operating the Melrin 46s at a 9lb boost limit at the time of the test.



The RAAF didn't raise the boost pressure until February 1943, and only to 12psi, all RAF Merlin 45 and 46's had been cleared for 16 psi in July 1942.


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## Vincenzo (Jul 22, 2020)

Reluctant Poster said:


> I don’t believe so. It states the Merlin 61 is for production in summer 1942.
> also it lists the Merlin 30 by 1943 it was replaced by the 32



it states that the Merlin 61 "already being tested for 66 1/2 inch..." in january '42? the production started in march


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## Reluctant Poster (Jul 22, 2020)

Vincenzo said:


> it states that the Merlin 61 "already being tested for 66 1/2 inch..." in january '42? the production started in march


Prototypes


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## Vincenzo (Jul 22, 2020)

Reluctant Poster said:


> Prototypes



and you use prototypes, practically hand built, for test the over boost to use on mass production engine, this is strange, but i'm not a technician
however all would be easy if we know the title and the collocation of the original document


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## Clayton Magnet (Jul 22, 2020)

PAT303 said:


> Have to agree with this, the '41 era MkV's didn't really offer anything over the Mk11 to be honest


So, in summary, if one wanted to make a Spitfire look as bad as possible against a contemporary, one would use the precise arrangement as in the original post? It is a wonder that they decided to even retract the gear

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## MIflyer (Jul 22, 2020)

Note that the report points out that the Spitfire suffered from having to use the Vokes tropical filter, which added drag and also reduced engine performance. Besides, it was incredibly ugly!

The Merlin used an updraft carb, which meant the air flowed from the bottom of the carb upwards. The British arranged the air intake of both the Spitfire and Hurricane to feed air to the carb with a minimum of hindrance, thereby enabling additional pressure to the engine from the ram air effect. The first noteworthy thing that Sir Stanley Hooker did at RR was pint out that from the theory standpoint the angles used in that installation were less than optimum.

But that meant the engine installation on the Spitfire and Hurricane had no air filter and so one had to be added externally.

In contrast the V-1710 used a downdraft carb, with air entering from the top, and so the air going to the carb had a ways to go to get there - and filters could be installed in that intake duct. Both the P-40M/N and P-51A had provisions for air filters and the Merlin Mustangs continued that feature when they had to move the intake duct to the bottom of the cowl.

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## Reluctant Poster (Jul 22, 2020)

Vincenzo said:


> and you use prototypes, practically hand built, for test the over boost to use on mass production engine, this is strange, but i'm not a technician
> however all would be easy if we know the title and the collocation of the original document


AFDU was running tactical trials with Spitfire IX No.BS.543 equipped with a Merlin 66 against Mustang X No. AM.203 fitted with a Merlin 65. Test results are dated 9th February 1943. The Mustang was being tested with the Merlin 65 at 18 inches boost in May 1942.

also the original document states “ Sabre IV in Typhoon II. Due for production in September 1942.” The paper was written in 1942.


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## Vincenzo (Jul 22, 2020)

Reluctant Poster said:


> AFDU was running tactical trials with Spitfire IX No.BS.543 equipped with a Merlin 66 against Mustang X No. AM.203 fitted with a Merlin 65. Test results are dated 9th February 1943. The Mustang was being tested with the Merlin 65 at 18 inches boost in May 1942.
> 
> also the original document states “ Sabre IV in Typhoon II. Due for production in September 1942.” The paper was written in 1942.



The first Mustang fly with a Merlin was in October '42, a Mustang X so i've many doubt that a Mustang can be test a Merlin65 in May '42


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## varsity07840 (Jul 22, 2020)

Schweik said:


> The P-40E (Kittyhawk 1A) was basically a slightly modified *P-40D* (Kittyhawk I), of which 600 made, which was basically only in use by the British who got about 560 of them between April and September of 1941. The US got about 40 and deverted maybe of those 20 to Canada. They were in action with the DAF in Egypt by January 1942. The P-40D represetned the big change from the P-40B and C by shortening the nose and putting the big guns in the wing. The early P-40Ds had two guns in each wing, but probably most of them had the traditional three guns in each wing like the P-40E. They were plumbed for an external fuel tank or a bomb on the centerline.
> 
> There were 2500 *P-40E */ Kittyhawk IA built, with most of them (about 1,500) again going to the British, a few hundred were sent to Java and the Philippines shortly before being destroyed largely on the ground by the IJA and IJN, as well as about 300 which arrived too late so were diverted into the hands of the Australians* (but some of those sank in their crates inside transport ships on the way). A (to me) unknown number were sent to New Zealand, but probably no more than 100, and another 300 or so to the 23rd FG (former AVG) in China. The British also sent probably a couple of hundred to the Russians though some of those only after they had been used (and a little worn out) in the Middle East. They originally had the same engine (V-1710-39) as the P-40D but some were actually re-engined in the field or at maintenance depots with the V-1710-73, though that may have only been done in Australia / New Guinea. Later run P-40E had two wing hard points and the centerline external fuel tank /r bomb hard point. They were able to carry up to three 250 lb bombs or more rarely, two 500 lb bombs for short hops. About halfway through the production run they changed the method of ammunition storage which reduced stoppages during high G maneuvers.
> 
> ...



I seriously doubt that the 23rd FG received that many P-40Es and P-40Ks.


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## Reluctant Poster (Jul 22, 2020)

Vincenzo said:


> The first Mustang fly with a Merlin was in October '42, a Mustang X so i've many doubt that a Mustang can be test a Merlin65 in May '42


Indeed. I read the date notation in American format (m/d/y) rather than English (d/m/y). The tests started in December 1942.
That still doesn’t change the fact that 5e memo was written In 1942.


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## Schweik (Jul 22, 2020)

varsity07840 said:


> I seriously doubt that the 23rd FG received that many P-40Es and P-40Ks.



23rd Fighter group had _mostly_ P-40E and P-40Ks. Most of their Aces flew P-40K, according to the Osprey book.

Some of the P-40E and Ks sent to China went to Chinese units (Chinese American composite group squadrons, 3rd and 5th FG), some went to India to the US 51st FG, and a few apparently to the 81st FG though maybe after already being used by the 23rd.


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## Schweik (Jul 22, 2020)

Does anyone have a link to the original report of the test from the OP? I thought i had a link but I can't find it.


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## Reluctant Poster (Jul 22, 2020)

Reluctant Poster said:


> Indeed. I read the date notation in American format (m/d/y) rather than English (d/m/y). The tests started in December 1942.
> That still doesn’t change the fact that the memo was written In 1942.


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## Vincenzo (Jul 22, 2020)

Reluctant Poster said:


> Indeed. I read the date notation in American format (m/d/y) rather than English (d/m/y). The tests started in December 1942.
> That still doesn’t change the fact that 5e memo was written In 1942.


do you know title and collocation of the memo?


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## Reluctant Poster (Jul 22, 2020)

MIflyer said:


> Note that the report points out that the Spitfire suffered from having to use the Vokes tropical filter, which added drag and also reduced engine performance. Besides, it was incredibly ugly!
> 
> The Merlin used an updraft carb, which meant the air flowed from the bottom of the carb upwards. The British arranged the air intake of both the Spitfire and Hurricane to feed air to the carb with a minimum of hindrance, thereby enabling additional pressure to the engine from the ram air effect. The first noteworthy thing that Sir Stanley Hooker did at RR was pint out that from the theory standpoint the angles used in that installation were less than optimum.
> 
> ...


This essay states that the lower performance with the Volkes filter was exaggerated
http://darwinspitfires.com/index.php?page=the-vokes-air-filter-controversy


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## Schweik (Jul 22, 2020)

There is a world war II vintage typed memo of the actual test results and descriptions I've seen it but I lost track of it.


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## Mike Williams (Jul 22, 2020)

Schweik said:


> Does anyone have a link to the original report of the test from the OP? I thought i had a link but I can't find it.

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## Reluctant Poster (Jul 22, 2020)

Vincenzo said:


> do you know title and collocation of the memo?


The memo refers to the Typhoon II which was renamed the Tempest in Feb 1942. So you‘re claiming that a year later the writer was unaware of the name change. The memo also notes that the Sabre IV will go into production in September 1942. The Sabre IV was the power plant for the Tempest I. Neither the engine nor the airframe went into production. Again a half a year later the author didn’t know that. And your case is based on?


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## Schweik (Jul 22, 2020)

Mike Williams said:


> View attachment 589386
> View attachment 589387



I forgot how hard that is to read. Thanks!

Where does it say what boost settings were being used ?


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## Mike Williams (Jul 22, 2020)

Schweik said:


> I forgot how hard that is to read. Thanks!
> 
> Where does it say what boost settings were being used ?



I don't think that report notes the boost settings. Maybe these apply:

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## Schweik (Jul 22, 2020)

If that is reflective of the conditions of the test then the p-40 was flying at restricted power ratings as well, 43 to 46 in of Mercury. So that would mean that both aircraft were flying below their highest power ratings.


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## Vincenzo (Jul 22, 2020)

Reluctant Poster said:


> The memo refers to the Typhoon II which was renamed the Tempest in Feb 1942. So your claiming that a year later the writer was unaware of the name change. The memo also notes that the Sabre IV will go into production in September 1942. The Sabre IV was the power plant for the Tempest. Neither the engine nor the airframe went into production. Again a half a year later the author didn’t know that. And your case is based on?


You're right on this, but the info on the Merlin are strange, at 3rd january '42 there was a alone Spitfire with a Merlin 60 flying, the next prototype ever with a 60, not a 61, go to fly only the 6th January, so the testing for the 66 1/2 inch boost are on land, on bench (? i'm not sure of the word)?

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## Reluctant Poster (Jul 22, 2020)

Vincenzo said:


> You're right on this, but the info on the Merlin are strange, at 3rd january '42 there was a alone Spitfire with a Merlin 60 flying, the next prototype ever with a 60, not a 61, go to fly only the 6th January, so the testing for the 66 1/2 inch boost are on land, on bench (? i'm not sure of the word)?


You’re right it is called a bench test. As you note there weren’t a lot of two stage Merlins around at that time it would be interesting to find out what they were testing. The Merlin 60 had the Kestel style block which wouldn’t be amenable to high pressure

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## PAT303 (Jul 22, 2020)

MIflyer said:


> In contrast the V-1710 used a downdraft carb, with air entering from the top, and so the air going to the carb had a ways to go to get there - and filters could be installed in that intake duct. Both the P-40M/N and P-51A had provisions for air filters and the Merlin Mustangs continued that feature when they had to move the intake duct to the bottom of the cowl.



The MkIX got a decent air filter arrangement, http://www.spitfireperformance.com/packard266-engine-installation.jpg unfortunately the MkV was the ugly princess that could almost be called a flying test bed for all the new equipment coming online as well as the different theaters and environments it would be used in.


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## Shortround6 (Jul 23, 2020)

Schweik said:


> If that is reflective of the conditions of the test then the p-40 was flying at restricted power ratings as well, 43 to 46 in of Mercury. So that would mean that both aircraft were flying below their highest power ratings.




This is quite true.

However the four combats listed in the document take place at

1. 20.000ft, about 1000ft under the book FTH of the Merlin 46(I don't know what the filter and tropical heat do to the FTH) and thousands of feet above the FTH of the P-40E.
Little or no change to the power available even if both engines are allowed higher boost, the superchargers won't deliver it at that altitude (well, maybe the Melrn 46 might get a few percent).

2. 16,000ft, two combats of the four. At this altitude the Merlin is in a quandary. at the 9lb limit power is down to about 1060hp (no ram, no filter effect, no tropical temperature. ) while at a 16lb limit it would have 1350hp (?) under the ideal conditions. (and less, the 16 lbs boost, FTH for 16lbs being 14,5000ft).
For the P-40E there is little or no change even if the boost limit was changed. It is at or above it's FTH and there is no more boost to be had. Manuals and books listing the altitude for the -39 engine in the P-40E are all over the place in regards to the altitude at which the engine could make 1150hp. From under 12,000ft to 15,000 feet depending on manifold, backfire screens and if RAM is counted or not.
Both combats descended into four digit altitudes, at the 9lb rating the Merlin 46 just gets weaker. At 8,000ft the Merlin 46 is under 1000hp at this boost limit. The -39 engine will get a bit stronger as the altitude drops from 16,000ft to that 12-15,000ft range and then start to fall off (but not as quickly as the Merlin) as the altitude goes even lower, however it should have a power advantage over the 9lb Merlin 46.
The Allison, if allowed higher boost, will start getting stronger as the altitude decreases below it's FTH and by 8,000ft will have a couple of hundred HP advantage of the Merlin at 9lbs. But the Merlin 46 will have more power at 8,000ft if allowed to use the 16lb limit.

3, the 13,000ft combat. means the P-40E is starting pretty much at FTH, the Merlin 46 is at just over 1000hp so the P-40E has about a 120-130 advantage which it keeps all the way down if both keep to the lower boost levels. If allowed higher boost the P-40E just keeps getting better down to 4-5000ft. If the Merlin is allowed 16lbs of boost the P-40 will make more power somewhere around 7,000ft (?) and is much better at the lower altitudes. 

Please note that a Merlin 45 (regular) is around 85-100hp more powerful than the Merlin 46 at the lower altitudes. 

Basicly the P-40E gets very little boost in power until about 10,000ft (1200hp) and by 8,000ft it is about 1300hp. 

For low level combat (under 8,000ft) the Boosted P-40 gets a considerable advantage but MK V Spit is going to show a very large advantage is allowed to use higher boost in the 5 digit altitudes.

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## varsity07840 (Jul 23, 2020)

Schweik said:


> 23rd Fighter group had _mostly_ P-40E and P-40Ks. Most of their Aces flew P-40K, according to the Osprey book.
> 
> Some of the P-40E and Ks sent to China went to Chinese units (Chinese American composite group squadrons, 3rd and 5th FG), some went to India to the US 51st FG, and a few apparently to the 81st FG though maybe after already being used by the 23rd.


The 23rd and 51st FGs were flying P-40Ms and P-40Ns through much of 1944.


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## Schweik (Jul 23, 2020)

Shortround6 said:


> This is quite true.
> 
> However the four combats listed in the document take place at
> 
> ...



Yeah I think you're right, the advantage that would be gained by using higher boost would break down differently by altitude between the two planes, and the p-40 would have much more of an advantage below 8000 feet whereas the Spit would have a higher critical altitude with boost and would still own the fight at 20k ft. And that would match the real world situation of course and I think they both did have significant advantages with boost.

But I don't think that it therefore follows that if the spitfire did the test that + 12 boost or + 14 and the P-40E was doing the test at 57 in of mercury that would mean that the spitfire would have a much bigger advantage in general or that the test would have come out different. Similarly if the boost went all the way to + 16 / 60 or 65 in.

I also suspect that a P-40L would have done pretty well in this test regardless of what boost levels were stipulated. But of course so would a Spit VIII or Spit IX (probably quite a bit more so).


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## Mike Williams (Jul 23, 2020)

Schweik said:


> If that is reflective of the conditions of the test then the p-40 was flying at restricted power ratings as well, 43 to 46 in of Mercury. So that would mean that both aircraft were flying below their highest power ratings.



+9 lbs boost for the Spitfire and +44" Hg. for the P-40E may be what the authorities at the Australian testing establishments thought those aircraft should be operating at during 1942-43 period. I've no idea what powers the operational units used in the field.

Looking at a couple of reports from Australia gives some context to the Comparitive Tests:
Kittyhawk Trials, Report No. F.8
Performance of Spitfire Vc - Tropicalized Version, C.S.I.R. Report F.12/1
Report on Comparitive Tests Capstan v. Kittyhawk (P40E)

Charts out about like so:

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## BobB (Jul 23, 2020)

RAAF pilot Nat Gould said that he never loved the Kittyhawk the way that he loved the Spitfire but that it brought him home with damage that would have destroyed a Spitfire and that the Spitfire simply couldn't have done the job in New Guinea due to its short range.

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## Schweik (Jul 23, 2020)

varsity07840 said:


> The 23rd and 51st FGs were flying P-40Ms and P-40Ns through much of 1944.



They only had a few P-40M, those were intended for export primarily, though they did get some through I don't know what path. P-40N did arrive in 1944 but by then they (23rd) were transitioning to Mustangs, and they were also still flying some K model fighters.

These pics are from the Osprey book on the 23rd Fighter Group. Notice the preponderance of P-40K'sm The majority of Aces flying for the group flew the P-40K.


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## Schweik (Jul 23, 2020)

varsity07840 said:


> The 23rd and 51st FGs were flying P-40Ms and P-40Ns through much of 1944.





Mike Williams said:


> +9 lbs boost for the Spitfire and +44" Hg. for the P-40E may be what the authorities at the Australian testing establishments thought those aircraft should be operating at during 1942-43 period. I've no idea what powers the operational units used in the field.
> 
> Looking at a couple of reports from Australia gives some context to the Comparitive Tests:
> Kittyhawk Trials, Report No. F.8
> ...



That is pretty eye opening.


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## overbeck (Jul 23, 2020)

PAT303 said:


> The RAAF didn't raise the boost pressure until February 1943, and only to 12psi, all RAF Merlin 45 and 46's had been cleared for 16 psi in July 1942.



Temperature is the likely reason for lower limits in Australia. The attached test (from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093190.pdf) is for an Allison with 6:1 compression and 9.6:1 blower gears, but the Merlin would be affected similarly. Knock occurs at 16 lbs boost at 60°F vs 11 lbs at 120°F. The mean in Darwin is 90°F, so maybe around 11.5 13.5 lbs for the Allison, less for the Merlin.

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## Mike Williams (Jul 24, 2020)

I got curious as to how typical the Australian test results were so had a look at other P-40E and Kittyhawk tests. The operational limitations of the V-1710 F3R engines which obtained at the time of the tests were generally 42" Hg., 3000 R.P.M. maximum for all out level or Military with the exception of the Australian test which was 44" Hg. The Australian P-40E performance doesn't look too bad in this context.

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## PAT303 (Jul 24, 2020)

overbeck said:


> Temperature is the likely reason for lower limits in Australia. The attached test (from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093190.pdf) is for an Allison with 6:1 compression and 9.6:1 blower gears, but the Merlin would be affected similarly. Knock occurs at 16 lbs boost at 60°F vs 11 lbs at 120°F. The mean in Darwin is 90°F, so maybe around 11.5 13.5 lbs for the Allison, less for the Merlin.



How were African/Mediterranean Spits able to run higher boost?, all RAF MkV's were cleared for 16 psi by August '42, all Australian Merlin 46's were cleared for 12 psi in Feb '43.


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## P-39 Expert (Jul 24, 2020)

Mike Williams said:


> Interestingly this chart for the Merlin 46 & 47 dated 27 March 1942 shows the +12 take off rating as well as the +16 Emergency rating.
> 
> View attachment 589238
> 
> ...


Those figures are with ram, right?


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## overbeck (Jul 24, 2020)

PAT303 said:


> How were African/Mediterranean Spits able to run higher boost?, all RAF MkV's were cleared for 16 psi by August '42, all Australian Merlin 46's were cleared for 12 psi in Feb '43.



North Africa is not tropical, for example Tobruk is 32°N, while Darwin is 12.5° S and usually hotter than Tobruk. Also cloud formation lowers the rate at which temperature falls with altitude, and that's much more common in Darwin. However, Merlins would have been running a bit harder in Africa/Med too than northern Europe. I guess not enough for the RAF to care about.

The RAAF only raised limits to 12 psi after the RAF raised theirs to 16, so were always 4 psi below. It's possible they didn't factor in temperature and were just being conservative because very long supply line.

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## Mike Williams (Jul 24, 2020)

overbeck said:


> The RAAF only raised limits to 12 psi after the RAF raised theirs to 16, so were always 4 psi below.





PAT303 said:


> Merlin 45's were cleared for 16psi boost @3,000rpm in July '42, 18psi in Feb '43, MkV LF's with Merlin 50's 18psi boost @ 3,000rpm May '43.





PAT303 said:


> The RAAF didn't raise the boost pressure until February 1943, and only to 12psi, all RAF Merlin 45 and 46's had been cleared for 16 psi in July 1942.



What sources did you guys use that support your statements related to dates and amount of boost? Thanks.


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## Mike Williams (Jul 24, 2020)

P-39 Expert said:


> Those figures are with ram, right?



The Merlin 46 & 47 chart shows max all-out level conditions, etc.


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## PAT303 (Jul 24, 2020)

Mike Williams said:


> What sources did you guys use that support your statements related to dates and amount of boost? Thanks.



I think it was originally posted by Edger Brooks?.

29.04.1941 - Spitfire V X.4922: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
18.06.1941 - Spitfire VB W.3134: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
xx.01.1942 Merlin 45 type test +16lbs boost. (The Merlin 100 series. RR Heritage Trust).
03.01.1942 - Ministry of Aircraft Production mentions +12 lbs and +15 lbs boosts
08.03.1942 - Spitfire Vc AA.873: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 20000 ft
30.06.1942 - No. 129 sqn ORB, speed tests at +16lbs boost.
29.07.1942 - R.D.T.3. R.D.E.2. R.T.P.7 Increased Rating for Merlin Engines. Approval 3,000rpm +16lbs boost Merlin 45,46 and 47 engines, operational units of Fighter Command. Previously only applicable to Seafire aircraft and for special applications. 3 minutes duration.
xx.08.1942 - Air Ministry issues memorandum declaring conversion to +16 lbs is currently done
25.11.1942 - Spitfire VC AA.878: Merlin 45 @ 3000 rpm/+16 lbs climb and level
27.01.1943 - Spitfire VB W.3322: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 20000 ft, 3000 rpm/+12 lbs take-off
03.02.1943 - 1 Sqn (Spitfire V tropicalized and Aboukir filter) clipped wings and +18lbs boost. SB.45457 Performance improvements on Spitfire F Mark V.
12.02.1943 - RAAF clears Merlin 46 and 47 for use of +12 lbs
25.05.1943 - Spitfire VB W.3228: cropped Merlin 50 @ 3000 rpm/+18 lbs climb and level


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## Shortround6 (Jul 24, 2020)

Mike Williams said:


> The Merlin 46 & 47 chart shows max all-out level conditions, etc.


While some of the Merlin charts do say "max all-out level conditions" this one
http://www.wwiiaircraftperformance.org/Merlin_46_47_Power_Chart.jpg 
does not. It does say "provisional"

It also differs only a little bit from the figures in "the Merlin in Perspective"

which gives 1415hp at 14,000 ft vs the 1440hp at 14,500ft in the chart. 

perhaps the chart, being provisional is a bit optimistic. But gains of only 500ft-1000ft in altitude for the effects of ram at full level speed seem awfully low. 

the last chart on your page for the Spitfire MK V compares 10 different planes (including Spitfire VI) using Merlin 46 and 47 engines. FTH for 9lbs and 3000rpm varies from 20,200ft to 22,600ft. 
FTH in climb (9lbs and 2850rpm) varies from 15,200ft to 18,000ft. the lowest performing engine is noted as below average. 

This may just add confusion


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## Schweik (Jul 24, 2020)

Mike Williams said:


> +9 lbs boost for the Spitfire and +44" Hg. for the P-40E may be what the authorities at the Australian testing establishments thought those aircraft should be operating at during 1942-43 period. I've no idea what powers the operational units used in the field.
> 
> Looking at a couple of reports from Australia gives some context to the Comparitive Tests:
> Kittyhawk Trials, Report No. F.8
> ...



If you are up for a challenge, how about adding a couple of other things that chart.

Spitfire V at +12 lb of boost Merlin 45 or 46
A6M2
BF 109E (any subvariant)
BF 109F2 or F4
F4F-3
Hurricane Mk I or II


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## Mike Williams (Jul 24, 2020)

Schweik said:


> If you are up for a challenge, how about adding a couple of other things that chart.
> 
> Spitfire V at +12 lb of boost Merlin 45 or 46
> A6M2
> ...



Interesting challenge  Maybe, we'll see. I thought I'd finish up that P-40E comparison exercise with a climb chart if I can get to it today.


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## Mike Williams (Jul 24, 2020)

Shortround6 said:


> While some of the Merlin charts do say "max all-out level conditions" this one
> http://www.wwiiaircraftperformance.org/Merlin_46_47_Power_Chart.jpg
> does not. It does say "provisional"
> 
> ...



I checked it out using the same sources you did and wasn't entirely satisfied. The Merlin 46 & 47 chart does, however, state "Emergency Max All Out Level Condition" and "Max All Out Level Power". It can be a tad confusing.


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## Shortround6 (Jul 24, 2020)

On second look you may be correct. The charts for the later engines don't have as many lines and the chart is labeled at the bottom that it is for 400mph in level flight or some like condition. This chart labels individual lines with different conditions.


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## Schweik (Jul 24, 2020)

I don't understand why the Spit is so slow at low altitude? Is that the Vokes filter? The wing is slightly shorter span than the P-40s wing and I think it's thinner. The Spit seems to be very streamlined, though it does have a few protrusions like the external tail wheel, so does the P-40 (gun camera and wheels not fully covered).

Where is all the drag coming from?


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## Shortround6 (Jul 24, 2020)

Schweik said:


> Spitfire V at +12 lb of boost Merlin 45 or 46
> A6M2
> BF 109E (any subvariant)
> BF 109F2 or F4
> ...




Quite a challenge.

The Merlin 45 and 46 are going to be different.
109Es came with a variety of engines. 
the 109F2 used a different engine than the F4

The F4F-3 should simply be a bit lighter than an F4F-4 (same engine)

Hurricanes used different engines. 

nine or more different aircraft?


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## Schweik (Jul 24, 2020)

Shortround6 said:


> Quite a challenge.
> 
> The Merlin 45 and 46 are going to be different.
> 109Es came with a variety of engines.
> ...



I wouldn't suggest trying to be completely comprehensive, I think the realistic approach would be to utilize what is available (like on WW2aircraftperformance.org, which he is already using I think), and try to shoot for what is typical rather than an outlier (if possible)


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## Mike Williams (Jul 24, 2020)

PAT303 said:


> I think it was originally posted by Edger Brooks?.
> 
> 29.04.1941 - Spitfire V X.4922: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
> 18.06.1941 - Spitfire VB W.3134: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
> ...



Thanks, that's helpful. There is this then:


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## Shortround6 (Jul 24, 2020)

Schweik said:


> I don't understand why the Spit is so slow at low altitude? Is that the Vokes filter? The wing is slightly shorter span than the P-40s wing and I think it's thinner. The Spit seems to be very streamlined, though it does have a few protrusions like the external tail wheel, so does the P-40 (gun camera and wheels not fully covered).
> 
> Where is all the drag coming from?




It is an interesting question.

The P-40 was actually a pretty streamline airplane, not a P-51 but compared to the Spitfire, the 109, ealy Yaks and even the Ki-61 it is a fast plane for the installed power. 

Compare to any other 1100-1200hp V-12 powered plane of your choice. 

What screwed it up was the weight, It was much heavier than any of the other planes in that catagory (except Mustang I) which meant climb sucked, and altitude performance sucked, high wing loading (despite larger wing than some) and low power to weight at altitude. 

I would note that the wheel covers came off during the time that Curtiss was trying to get the XP-40 to go from a first tested 299mph (with rear radiator) up to about 340mph so I would guess that Curtiss knew exactly what those wheel covers were worth in terms of drag.


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## overbeck (Jul 24, 2020)

Schweik said:


> I don't understand why the Spit is so slow at low altitude?



Single speed supercharger. With a 20 series Merlin it would be faster low down than a P-40.

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## Schweik (Jul 24, 2020)

Shortround6 said:


> It is an interesting question.
> 
> The P-40 was actually a pretty streamline airplane, not a P-51 but compared to the Spitfire, the 109, ealy Yaks and even the Ki-61 it is a fast plane for the installed power.
> 
> ...



I don't think the wing loading was actually that high - at 31- 35 lb / sq ft (depending on the variant) it's lower than most other monoplane fighters outside of Japan. We have touched on that before.

My numbers:

P-40B at 6,835 loaded - 31 lb 
P-40E-1 at 8,280 loaded - 35.1 
P-40K-15 at 8,400 loaded - 35.6
P-40F-5 at 8,480 loaded - 35.9 (6 guns)
P-40L-10 at 8,020 loaded - 33.9 (4 guns)
P-40N-1 at 7,730 loaded - 31.36 (4 guns)

As we know, the Soviet turn-time tests also showed the P-40 as out-turning most other aircraft except the Spitfire & the Hurricane


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## Schweik (Jul 24, 2020)

overbeck said:


> Single speed supercharger. With a 20 series Merlin it would be faster low down than a P-40.



I was trying to look up speed tests for Spit V's but most of them seem to start at 8,000 ft


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## Mike Williams (Jul 24, 2020)

Schweik said:


> I was trying to look up speed tests for Spit V's but most of them seem to start at 8,000 ft



The lower altitude speeds can be extrapolated:

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## Schweik (Jul 24, 2020)

Sadly I've never found original performance test data for a P-40K

How about adding a P-40F

http://www.wwiiaircraftperformance.org/P-39/P-39D-PHQ-M-19-1325-A.jpg


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## Schweik (Jul 24, 2020)

From this and a couple of others I looked at, it appears that the 109E would also be slower than P-40E below 12,000 ft


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## Shortround6 (Jul 24, 2020)

For the P-40K (and any P-40 using the 8.80 supercharger gear) the speeds above the sharp break/angle in the line are going to be the same, subject to minor changes in drag (racks,fittings) it is how far down (lower altitude) the upper curve will go before you get the sharp break and the straight line going down to sea level. 

Some numbers from "Curtiss Fighter AIrcraft 1917-1948" by Dean and Hagedorn give 320mph at 5,000ft, 343mph at 10,000ft and 362mph at 15,000. 
No comment on what power levels were used. However unless over boosted the engine would give the same power as the engine in the P-40E, the 1325hp at take-off being a special condition?


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## slaterat (Jul 24, 2020)

Schweik said:


> If you are up for a challenge, how about adding a couple of other things that chart.
> 
> Spitfire V at +12 lb of boost Merlin 45 or 46
> A6M2
> ...




Here some comparative charts that might be of interest to you.

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## Schweik (Jul 24, 2020)

Shortround6 said:


> For the P-40K (and any P-40 using the 8.80 supercharger gear) the speeds above the sharp break/angle in the line are going to be the same, subject to minor changes in drag (racks,fittings) it is how far down (lower altitude) the upper curve will go before you get the sharp break and the straight line going down to sea level.
> 
> Some numbers from "Curtiss Fighter AIrcraft 1917-1948" by Dean and Hagedorn give 320mph at 5,000ft, 343mph at 10,000ft and 362mph at 15,000.
> No comment on what power levels were used. However unless over boosted the engine would give the same power as the engine in the P-40E, the 1325hp at take-off being a special condition?



Three comments on that -

That would 14 mph faster than the P-40E in the Australian test we've been looking at.
I would agree with you that what you mentioned there probbaly represents takeoff power of 1,325 Hp, which is achieved at 51" Hg
However the _normal_ WEP rating (not overboost) for the P-40K-15 was 60" Hg for 1,550 hp. So that would be 15% more power.
My source for that is Shamburger, Page & Christy, Joe. _The Curtiss Hawks_. Wolverine Press, 1972. Library of Congress No. 79-173429 , page 231

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## Mike Williams (Jul 24, 2020)

Schweik said:


> Sadly I've never found original performance test data for a P-40K



These are all the test reports I'm seeing for the P-40K fwiw:

Memorandum Report on P-40K-1, A.A.F. No. 42-9761: Speed Tests - Normal and Smooth Camouflage
Memorandum Report on P-40K-1, A.A.F. No. 42-9761 (addendum): Speed Tests


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## Schweik (Jul 24, 2020)

Yeah I've seen those, except the second page on the addendum, which is interesting (and better than nothing) but still doesn't tell us very much and apparently done at military power. All they were looking at there was what difference smoothing the paint made.

There must be a proper evaluation of the K model both by the USAAC, RAF, and probably the Soviets too. I know there is a document on WWIIaircraftperformance.org where they used a P-40K in some tests against a Zero and another where they used it against some Allied aircraft but I couldn't find them, they aren't in the P-40 section.


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## Mike Williams (Jul 24, 2020)

Fwiw, more on the Spitfire V, P-40E/Kittyhawk comparison. These P-40s were just not good climbers. Too much weight and not enough power I suppose.

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## Schweik (Jul 24, 2020)

No they weren't, though it helped to boost the power by 15-20% which was just a matter of pushing the throttle forward, and / or drop the weight a bit.


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## varsity07840 (Jul 24, 2020)

Schweik said:


> Yeah I've seen those, except the second page on the addendum, which is interesting (and better than nothing) but still doesn't tell us very much and apparently done at military power. All they were looking at there was what difference smoothing the paint made.
> 
> There must be a proper evaluation of the K model both by the USAAC, RAF, and probably the Soviets too. I know there is a document on WWIIaircraftperformance.org where they used a P-40K in some tests against a Zero and another where they used it against some Allied aircraft but I couldn't find them, they aren't in the P-40 section.



A P-40K and a P-43 were test flown against an A6M2 captured by China after it crashed landed on a beach in 1941. In 1942 it was rebuilt by Chinese and American technicians and tested in early 1943.


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## Schweik (Jul 24, 2020)

varsity07840 said:


> A P-40K and a P-43 were test flown against an A6M2 captured by China after it crashed landed on a beach in 1941. In 1942 it was rebuilt by Chinese and American technicians and tested in early 1943.



I think that test is on world warIIaircraft performance.org somewhere


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## Mike Williams (Jul 24, 2020)

Schweik said:


> No they weren't, though it helped to boost the power by 15-20% which was just a matter of pushing the throttle forward, and / or drop the weight a bit.



Was there some kind of cooling issues during climb? Oil temps high? It would have helped if 3000 R.P.M. could have been used as well as the same boost as with level flight, for example 44" Hg. while climbing. I was hoping I could work up a 44" Hg./3000 rpm curve extrapolated from the Australian test but the 2600 R.P.M. used sort of complicates that notion.


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## Mike Williams (Jul 24, 2020)

varsity07840 said:


> A P-40K and a P-43 were test flown against an A6M2 captured by China after it crashed landed on a beach in 1941. In 1942 it was rebuilt by Chinese and American technicians and tested in early 1943.



Oh yea, good one, here you go: General Technical Data and Flight Characteristics of the Japanese Zero Fighter Plane

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## Mike Williams (Jul 24, 2020)

Schweik said:


> Three comments on that -
> 
> That would 14 mph faster than the P-40E in the Australian test we've been looking at.
> I would agree with you that what you mentioned there probbaly represents takeoff power of 1,325 Hp, which is achieved at 51" Hg
> ...



That's a significant power increase. That 60" must be mentioned in a P-40K Pilot's Notes or Operating Instructions sheet somewhere? Was the radiator or oil cooler improved from the P-40E to the P-40K or N to accommodate the increase in power?


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## varsity07840 (Jul 24, 2020)

Mike Williams said:


> Oh yea, good one, here you go: General Technical Data and Flight Characteristics of the Japanese Zero Fighter Plane


I recall reading that years ago along with critiques of the report. Given the statement that the engine could produce 900 HP, it's obvious that the engine/aircraft was not in service condition. A favorable comparison of the P-36A to the Zero confirms that. Pilots that flew the P-36A against the Zero on Dec. 7th would have disagreed with that report.


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## Schweik (Jul 24, 2020)

Mike Williams said:


> That's a significant power increase. That 60" must be mentioned in a P-40K Pilot's Notes or Operating Instructions sheet somewhere? Was the radiator or oil cooler improved from the P-40E to the P-40K or N to accommodate the increase in power?



No, apparently a change to radiator or oil cooler wasn't needed (or if it was, I'm unaware of it). Allison changed the crank shaft to first a peened and then tempered homogeneous construction, then they also strengthened the crank case too. As far as I know that is the only major difference between the V-1710-39 on the P-40E and the V-1710-73 on the P-40K

The official 60" / +15 lb boost rating is mentioned twice in the famous Dec 1942 Allison memo here:

http://www.wwiiaircraftperformance.org/P-40/V-1710_Service_Use_of_High_Power_Outputs.pdf

That memo is from Alison to the War Dept., complaining about P-40 units overboosting in the field (in the Middle East and in Australia), and warning that there will be a risk of problems when the new Allisons with higher gear ratios make it to the field (on P-40M and P-40N fighters) but we don't have to concern ourselves with overboosting.

To quote them "_The engines under discussion are of the -F3R and -F4R type with 8.8:1 blower ratio on which this company has agreed to the war emergency operation at 60" manifold pressure (15 lbs / sq.in.boost) and approximately 1570 H.P. at 3000 R.P.M_"

Later they say:

"_In determining the 57" hg. war emergency rated manifold pressure Amendment 5 fuel was used and the detonation point was stayed away from at 120 degrees F. carburetor air temperature with the engine running at 3,000 R.P.M. The 60" war emergency rating on the 8.8 blower ratio was somewhat further from the detonation point but was limited by structural limitations of the engine to the 60" value. We therefore feel that, with the tendency to pull out a manifold pressure such as 66" to 70" on 8.8 blower, a bad precedent is being established which may cause numerous failures when the 9.6:1 supercharger gear ratio engines are received in the field._"

There is another memo somewhere which talks about the changes done to the Allison, but I seem to have lost track of where any of that stuff is, I think it's on WWIIaircraftperformance as well but I'm not sure. Shortround6 might know.

The only manual I have on the P-40K is a manual for overhauling the engine. The P-40N manual mentions a WEP rating of 57" for 1480 HP (page 4 of the PDF) but it had the higher gear ratio engine that Allison was warning about.

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## Schweik (Jul 24, 2020)

I assumue "Amendment 5 Fuel" means British high octane fuel but I don't remember if we ever proved that.


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## Schweik (Jul 24, 2020)

The manual for the P-40F and L (merlin engines) says the WEP rating which is apparently some kind of automatic setting, is 61" Hg (page 7 of the PDF) and it says that WEP is available in both low and high gear, use low gear below 8,000 ft and high gear above 8,000 ft. Later on page 42 the Critical altitude for WEP is listed as 4,600' for low gear and 12,000 ft for high gear.

See attached


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## Schweik (Jul 24, 2020)

varsity07840 said:


> I recall reading that years ago along with critiques of the report. Given the statement that the engine could produce 900 HP, it's obvious that the engine/aircraft was not in service condition. A favorable comparison of the P-36A to the Zero confirms that. Pilots that flew the P-36A against the Zero on Dec. 7th would have disagreed with that report.



Oh yeah I agree, it's obvious they didn't get the A6M running properly. I was only looking for the report hoping for some more data on the P-40K but there really wasn't much.


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## Shortround6 (Jul 24, 2020)

Problems with the P-40 are the large amount of weight they were trying to lift (when climbing) with 1150hp or less.

*Standard US procedure was to use military power for the first 5 minutes of the climb (42-44in in the case of the P-40s and the full 3000rpm)* 

British and Australian testing may do the P-40 a disservice if they use the 2600rpm and lower boost for the entire climb.

Both countries used a 5 minute full power rating (or sometimes 3 for the British) but the British then dropped to a 30 minute rating (and used that for all climbing tests) while the Americans didn't use that time period at all, the Americans dropped to either a one hour rating or (same rating different name) max continuous which was good for as long as the fuel lasted or a temperature gauge went into the red. The British/Australian climb tests are using the max continuous rating which for the Allison In the P-40 was about 1000hp. 

The P-40 would have climbed very well indeed had the supercharger been able to supply 60in (or even 56in) for more than a minute or two when climbing. 
The 60 in limit on the P-40 K was all done at 2500ft no RAM or a bit over 3000ft when at climb speed. High speed level flight was good for a bit higher.

The 56in limit was good for for 4300ft NO RAM. there is little or no difference between the superchargers on an E or a K. When Climbing the the K could have had 60in at sea level (on a standard day) and held it to around 3000ft but then the pressure would decline until at something over 4300ft the pressure was down to 56in as the plane continued to climb (far into the 2nd minute or start of the 3rd?) the pressure in the manifold would continue to drop as the supercharger just cannot supply anymore air at an engine speed of 3000rpm, Until you hit the high 11s or low 12s ft at which point the supercharger, with wide open throttle is supplying 42in in the case of the K. again, sources are all over the place depending on exact manifold and backfire screens. 



Mike Williams said:


> That's a significant power increase. That 60" must be mentioned in a P-40K Pilot's Notes or Operating Instructions sheet somewhere? Was the radiator or oil cooler improved from the P-40E to the P-40K or N to accommodate the increase in power?



There was no real change in the radiator or oil cooler but the engine in the K used mixed water/glycol cooling instead of pure glycol like the engine in the E. This gave a better heat transfer and coped with the increase heat load.

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## Shortround6 (Jul 24, 2020)

Schweik said:


> The manual for the P-40F and L (merlin engines) says the WEP rating which is apparently some kind of automatic setting, is 61" Hg (page 7 of the PDF) and it says that WEP is available in both low and high gear, use low gear below 8,000 ft and high gear above 8,000 ft. Later on page 42 the Critical altitude for WEP is listed as 4,600' for low gear and 12,000 ft for high gear.
> 
> See attached


I would note that the HP ratings on the chart for WEP are in error. A simple typo I suppose.


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## Schweik (Jul 24, 2020)

Shortround6 said:


> Problems with the P-40 are the large amount of weight they were trying to lift (when climbing) with 1150hp or less.
> 
> *Standard US procedure was to use military power for the first 5 minutes of the climb (42-44in in the case of the P-40s and the full 3000rpm)*
> 
> ...



All true - and they wouldn't normally try to climb at high power anyway because it's very wasteful of fuel. But if for example they had to scramble to deal with an inbound attack, or if they were already flying, in combat, and needed to climb up to engage an enemy they would indeed use boost and in your scenario described above, they would still be for the first 3 minutes of a climb from sea level up to 10,000 ft at 60" down to 56" boost which is still way above what was recorded in any of those tests. After that it falls down to more or less the same as in the tests (not very good), but that is why a P-40E or K was basically a low to medium altitude aircraft. If the fight wasn't going well at 15,000 or 20,000 ft they could drop down to 8,000 or so in less than a minute.

The P-40F or L as you can see in my previous post was able to make 61" boost certainly up to 12,000 ft., and as you can see here on the P-40N ...

http://www.wwiiaircraftperformance.org/P-40/A29-412-climb-WEP.jpg

...climb at (57") WEP started at over 3,100 ft per minute, got up to about 3,370 (at 6,800 ft) and was still pretty decent at 15,000 ft (2300), up to about 18,000' where falls below 2,000 fpm.

Of course, that is at the maximum steepest climb rate at 150 mph, which is not going to happen around enemy aircraft, so realistically they would be zoom climbing or doing a high speed climb, but the extra power would help regardless.

For speed it gives a WEP full throttle height of 9200' for the P-40N and still some power all the way up to about 20 or 22,000



> There was no real change in the radiator or oil cooler but the engine in the K used mixed water/glycol cooling instead of pure glycol like the engine in the E. This gave a better heat transfer and coped with the increase heat load.



That's interesting I wasn't aware of that.


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## Schweik (Jul 24, 2020)

Shortround6 said:


> I would note that the HP ratings on the chart for WEP are in error. A simple typo I suppose.



Yeah that seems to be the number they always throw around for the P-40F, it should be 1430 or something right? That confused me for a long time when I was first researching the P-40F / L. How is that calculated precisely? Or is it based on a bench test or something?


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## PAT303 (Jul 24, 2020)

Schweik said:


> Where is all the drag coming from?



Cannon barrels, undercarriage, tail wheel, windscreen angle, exhaust stacks, fit and finish. I have a report on paint condition and it's relevance to speed done on a squadron sourced Spit XIV, repainting and polishing added 14mph to it's speed, many of the MkV's in use were getting tired after giving years of loyal service.

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## Mike Williams (Jul 24, 2020)

Googled this P-40K specific engine flight chart that shows 60" emergency boost.

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## Schweik (Jul 24, 2020)

Mike Williams said:


> Googled this P-40K specific engine flight chart that shows 60" emergency boost.
> 
> View attachment 589607



Well done! I tried googling that & found zip.


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## Schweik (Jul 25, 2020)

So how fast is a P-40 with 1550 hp?


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## Kevin J (Jul 25, 2020)

Schweik said:


> So how fast is a P-40 with 1550 hp?


If an A-36 did AFAIK 344 at sea level, 364 at both 5000 and 15000 feet then surely if a P-40K does 362 at 15000 feet then it should do 362 at 5000 and 342 at sea level. Clean condition, take off 12 for in the field. Spitfire LF VC Merlin 55M did 331 at sea level, 358 at 5900 so closely matched at similar powers.


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## Schweik (Jul 25, 2020)

I don't know about that. A-36 was far better streamlined I think. Pseudo-laminar flow wings etc.


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## Kevin J (Jul 25, 2020)

Schweik said:


> I don't know about that. A-36 was far better streamlined I think. Pseudo-laminar flow wings etc.


Agreed, except the A-36 had bomb racks and dive brakes. So let's say that costs 20 mph. P-51 does 382 mph P-40E 362 mph. Ipso facto the speed gap is now closed. P-51A does 378/409 mph, fasted P-40N, 378 mph, same armament, speed gap opened again.

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## Schweik (Jul 25, 2020)

It's a reasonable speculation but it's still conjecture. I'd love to see a speed test they must have done one.

How many other early- to mid-war fighters could do over 300 miles an hour down at sea level?

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## Kevin J (Jul 25, 2020)

Schweik said:


> It's a reasonable speculation but it's still conjecture. I'd love to see a speed test they must have done one.
> 
> How many other early- to mid-war fighters could do over 300 miles an hour down at sea level?


The Whirlwind, Spitfire, Typhoon in the RAF.


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## Schweik (Jul 25, 2020)

LF model or spit 8/ 9 or later though right?


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## Kevin J (Jul 25, 2020)

Schweik said:


> LF model or spit 8/ 9 or later though right?


Spitfire I: 12 lbs boost, 305 mph; 16 lbs boost, 319 mph? Rolls Royce mod'd a Whirlwind, under engine radiators, 362 mph; Whirlwind on 100 octane, 329 mph IIRC.

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## Schweik (Jul 25, 2020)

I had somehow missed this before, but this is the highest performance (speed) I've seen on an official test for the P-40F. This is a 6 gun P-40F full fuel, but no ammunition. Test was April 1943.

Top speed at 18,000 ft was 374 mph without the belly tank sway braces, 369.5 with the sway braces.

http://www.wwiiaircraftperformance.org/P-40/P-40F_41-13635_FS-M-19-1578-A.pdf

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## Schweik (Jul 25, 2020)

Kevin J said:


> Spitfire I: 12 lbs boost, 305 mph; 16 lbs boost, 319 mph? Rolls Royce mod'd a Whirlwind, under engine radiators, 362 mph; Whirlwind on 100 octane, 329 mph IIRC.



Whirlwind was a damn beast down low. I was just reading the Tempest V had 376 mph at Sea level that's incredible. But Whirlwind was right at the beginning. I know I got shouted down for saying this before but they should have kept that project going.

One chart for the Beaufighter VI shows 312 mph at 4,000 ft so it's probably up around 300 mph in speed at Sea level, which helps explain how it survived combat with single engined fighters down low.

Looks like 109E-3 was around 270-290 mph at Sea Level
I couldn't find any specific chart on the 109F
109G could do 310-320 mph at Sea Level depending on a variety of factors.

A6M2 was ~ 270 mph at Sea Level and broke 300 mph at 6,000 ft
A6M5 was about 295 mph at Sea Level at WEP
Ki-43 was about 290 mph at Sea Level with WEP

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## PAT303 (Jul 26, 2020)

Schweik said:


> I don't know about that. A-36 was far better streamlined I think. Pseudo-laminar flow wings etc.



Remember too that you sacrifice speed to gain in other area's, the Hispano cannon barrels cost the Spit about 7 mph but each hit with the power equivalent to three .50 brownings, the Mustang lost speed changing from the birds cage to the Malcolm hood, then the bubble canopy but pilots aren't going to complain about the better visibility.


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## Mike Williams (Jul 26, 2020)

I'm uncertain how useful this comparison is. Different P-40 variants with different engines, conditions and engine powers. It shows quite a range of performance obtained during testing if nothing else.

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## Schweik (Jul 26, 2020)

There is another data point on the P-40F or L from the RAF in Sept 1942 here, giving speeds at two altitudes

http://www.wwiiaircraftperformance.org/P-40/Kittyhawk_II_performance_9sept42.jpg

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## Schweik (Jul 27, 2020)

Could you add those last two data points to the chart? I think it would make a short line...


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## Conslaw (Jul 30, 2020)

Kevin J said:


> Spitfire I: 12 lbs boost, 305 mph; 16 lbs boost, 319 mph? Rolls Royce mod'd a Whirlwind, under engine radiators, 362 mph; Whirlwind on 100 octane, 329 mph IIRC.



Perhaps someone can clarify something. The converter that I found online equates 16 lbs/sq.inch to only 33 inches of mercury. 33 inches of mercury isn't much at all. Am I missing something?


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## Schweik (Jul 30, 2020)

Conslaw said:


> Perhaps someone can clarify something. The converter that I found online equates 16 lbs/sq.inch to only 33 inches of mercury. 33 inches of mercury isn't much at all. Am I missing something?



Yes that's wrong. It's not a direct conversion as IIRC boost and manifold pressure are measured at different stages of the supercharging process

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## wuzak (Jul 30, 2020)

Conslaw said:


> Perhaps someone can clarify something. The converter that I found online equates 16 lbs/sq.inch to only 33 inches of mercury. 33 inches of mercury isn't much at all. Am I missing something?



The British system used boost pressure above standard sea level pressure.

It is usually indicated by the plus (+) or minus (-) sign in front of the boost number. +16psi boost is 30.7psi absolute pressure.

So the MAp of +16psi is ~62.5inHg.

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## Todd Secrest (Jul 30, 2020)

What was the cost to manufacture the Allison V-12 vs the Merlin V-12? 
I heard the Merlin used almost twice as many parts, compared to the Allison?


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## pbehn (Jul 30, 2020)

Todd Secrest said:


> What was the cost to manufacture the Allison V-12 vs the Merlin V-12?
> I heard the Merlin used almost twice as many parts, compared to the Allison?


The answer comes out as "how long is a piece of string". Merlins from Glasgow were probably extraordinarily cheap as far as payment to RR goes, once the government had built the factory, put all the tools in, built the workers houses and recruited the workforce that they also guaranteed payment and work for one way or another.


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## Shortround6 (Jul 30, 2020)

Todd Secrest said:


> What was the cost to manufacture the Allison V-12 vs the Merlin V-12?
> I heard the Merlin used almost twice as many parts, compared to the Allison?



There are parts and there are parts. 
Both are V-12s with 4 valves per cylinder. 
The Merlin used quite a number of screws/nuts/washers to hold valve covers and other things on and perhaps more fasteners to hold some of the internal parts in place. 
It does take more time to deal with all the extra fasteners but using the total number of "parts" to try to compare cost is rather bogus.

How many machine operations to make each crankshaft could be similar or way different depending on the machinery available.


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## Reluctant Poster (Jul 30, 2020)

Shortround6 said:


> There are parts and there are parts.
> Both are V-12s with 4 valves per cylinder.
> The Merlin used quite a number of screws/nuts/washers to hold valve covers and other things on and perhaps more fasteners to hold some of the internal parts in place.
> It does take more time to deal with all the extra fasteners but using the total number of "parts" to try to compare cost is rather bogus.
> ...


Here's what the Fedden Mission had to say about production of the V-1710

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## Reluctant Poster (Jul 30, 2020)

Here is the Fedden Mission on the subject of Packard production

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## Todd Secrest (Jul 30, 2020)

Shortround6 said:


> There are parts and there are parts.
> Both are V-12s with 4 valves per cylinder.
> The Merlin used quite a number of screws/nuts/washers to hold valve covers and other things on and perhaps more fasteners to hold some of the internal parts in place.
> It does take more time to deal with all the extra fasteners but using the total number of "parts" to try to compare cost is rather bogus.
> ...


deleted.


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## GregP (Jul 30, 2020)

Hi Todd,

For the cost difference:

One way you might look at it is by man-hours expended per engine overhaul. They have records for this for every month of the war from Jul 43 through Aug 45 in the Army Air Forces Statistical Digest of WWII, Table 115.

The two engine types you asked about were the Merlin (or V-1650) and the Allison (or V-1710).

For the V-1650:
Man-hours started out in Jul 43 at 462 hours.
For the entire war by month: High: 592 man-hours; Average: 320 man-hours; Low: 190 man-hours.

For the V-1710:
Man-hours started out in Jul 43 at 376 hours.
For the entire war by month: High: 376 man-hours; Average: 191 man-hours; Low: 117 man-hours.

Let's be fair and acknowledge that the average comes down as the workers get familiar with the engine. So, let's use the average: On average, it took 320 man-hours to overhaul a Merlin and 191 man-hours to overhaul an Allison. So, they can overhaul an Allison in 59.7% of the time it took for a Merlin.

I worked at a shop that overhauls Allisons for almost 4 years. In that time, we did some work on a couple of Merlins. Everything in a Merlin took longer, not just because we weren't as familiar with the Merlin, but also because the design is harder to work on in general (takes longer). As an example, in service you have to tighten the cylinder hold down nuts every 25 hours of operation. On an Allison, the cylinder banks are torqued down to 1,100 foot-pounds and never have to be touched until overhaul. Valve seats are another difference. You screw in the Merlin valve seats until they snap off the stud. Allison valve seats are permanent and are harder and more easily ground. Merlin valve seats are not so easily ground and are more likely to be replaced and than ground. I'd say that manufacture of a Merlin would take about 20 - 30% longer for machining and 40% longer for assembly.

So, let's try an example using 25% longer for manufacture. Say we can make an Allison V-1710 with 40 hours of casting, 300 hours of machining, and 50 hours of assembly. The casting should be very slightly longer for the Merlin, so it might come in at 50 hours casting, 375 hours of machining, and 70 hours assembly. The Allison takes 390 hours total and the Merlin takes 495 hours total.

Now, I pulled those Allison numbers above out of my hat (and by extrapolation, the Merlin numbers as well), but the percentages won't be too far off. So, my estimate is the Merlin takes, in total, about 27% more time and cost to manufacture, give or take a bit, and it takes about 40% more time to overhaul a Merlin when compared with an Allison overhaul.

Here's the thing, in my experience, the Merlin is as reliable as an Allison in field operation (after the initial Allison faults were ironed out ... took about 9 months or so), but the Allison runs longer before an overhaul is needed in non-turbo operation (P-39 / P-40 / A-36). I say non-turbo operation because today (my experience), almost all Allisons are operated without the turbochargers. If you think it might be hard to find parts for an Allison V-1710, try finding parts for an 85-year old turbocharger! If you needed high-altitude performance, the Merlin was your better choice for WWII. If you were flying in the PTO or Med, either one would do fine. The Allison cost was less to manufacture and overhaul, but it wasn't really a factor for military operations since the units didn't pay for aircraft ... they operated them. The Merlin used slightly more fuel than the Allison but that, too, was of little consequence because they had enough fuel for operations.

In service, there was little to choose between them once the initial problems with the Allison were ironed out, unless higher altitudes were required. If they were, the Merlin was the choice if there WAS a choice. Mostly, there wasn't a choice. If your unit flew P-38s, you generally didn't have the option to trade them in for P-51B/C/D/Ks. The USAAF made that choice for you, and U.S. units didn't GET Merlins until we started accepting P-51B/Cs, so we are talking after the summer of 1943 to come off the assembly line and late 43 or into 44 before our guys were flying Merlins overseas, at least in P-51s. So, we only had about a year and a half of time when we were operating both engines in numbers. The Brits were operating them together far longer than we were.

Second, why would you believe the Merlin was a double overhead cam? Download a pdf manual from this forum and check it out to be sure.


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## Todd Secrest (Jul 30, 2020)

GregP said:


> Hi Todd,
> Second, why would you believe the Merlin was a double overhead cam? Download a pdf manual from this forum and check it out to be sure.


I just assumed the Merlin was dual overhead cam, but never thought to check that fact out.
(As the merlin was said to have more parts)


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## GregP (Jul 30, 2020)

There is a manual section. On the place where you select "Aviation," look down a bit and see "Technical," and go to "Engines." You can find pdf manuals for service and overhaul for most of the important engines.

Cheers!  no disrespect intended with the comment above.

Oh, and the estimate above would be for similar single-stage engines. The different might be a bit more for the Merlin 60 series and the rest of the 2-stage units.


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## Schweik (Jul 30, 2020)

You mean supercharger not turbo right?


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## Conslaw (Jul 30, 2020)

wuzak said:


> The British system used boost pressure above standard sea level pressure.
> 
> It is usually indicated by the plus (+) or minus (-) sign in front of the boost number. +16psi boost is 30.7psi absolute pressure.
> 
> So the MAp of +16psi is ~62.5inHg.



Ok, so you add sea level pressure to the conversion factor, which is just under 30 psi. That makes sense. Thank you.


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## GregP (Aug 3, 2020)

Hi Schweik, 

No turbocharger. Just to be clear, aircraft Allison V-1710s all had an integral supercharger. I think there might be some PT boat Allisons that did NOT have a supercharger. I have seen one, complete with drive gear, but did not pay any attention at the time to the supercharger because it was on a storage shelf and I couldn't see the accessory end of it since there were other Allisons on either side of it. It may or may not have had the supercharger. The power section looked identical to a V-1710, at least from the front quarter view.

The P-38 has both an integral supercharger and a remote turbocharger. The control system for the turbocharger gave some initial issues in the ETO in the P-38 in WWII. Today, not many Allisons actually run the turbocharger except for tractor-pull engines, many of which have rather exotic setups ... not many WWII turbos ANYWHERE are running. I think there is ONE P-38 and ONE P-47 that have operating turbochargers, but that was a few years back when I KNEW they were operating. Might still be operating, but also might not ... sort of depends if they had any major issues with the turbos, and the cache of spare turbo parts if so.

Here's an "exotic" setup:






The engines LOOK stock, but I have seen pics of Allisons in tractors that look like the supercharger was replaced with Hilborn injection:






Like the one above. That intake setup is nothing any WWII vehicle ever saw.

At any time, it isn't difficult to lock the turbocharger from the system. All you have to do is lock the wastegate so it bypasses the turbocharger, and then lock the exhaust turbine so it doesn't rotate. Presto, non-turbo operation.

I'd pretty much assume that the operating B-17s and B-24s (or PB2Ys) also are running in non-turbo mode since parts for their turbos aren't any easier to find, and there is NO reason for any of them to be at 25,000+ feet today. Even the B-29 "Doc" was restored without operating power recovery turbines. I could be wrong and maybe someone IS running turbos, but I'd have to see that to believe it.

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## Schweik (Aug 3, 2020)

Right, but you keep saying turbocharger, which for the Allison, was only on the P-38. The P-40, P-39, P-51A had the integral supercharger, are you saying they bypass that?


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## GregP (Aug 4, 2020)

No, the supercharger is running when the crankshaft is turning. The carburetor feeds the supercharger impeller, which exits directly into the intake manifold. Can't shut off the S/C without shutting off the engine.






The S/C impeller is the small turbine-looking thing on the right, under the carburetor.

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## Schweik (Aug 4, 2020)

GregP said:


> I say non-turbo operation because today (my experience), almost all Allisons are operated without the *turbochargers*. If you think it might be hard to find parts for an Allison V-1710, try finding parts for an 85-year old *turbocharger*! If you needed high-altitude performance, the Merlin was your better choice for WWII. If you were flying in the PTO or Med, either one would do fine. The Allison cost was less to manufacture and overhaul, but it wasn't really a factor for military operations since the units didn't pay for aircraft ... they operated them. The Merlin used slightly more fuel than the Allison but that, too, was of little consequence because they had enough fuel for operations.



I assume you are referring to P-38s here then?


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## Dimlee (Aug 6, 2020)

Schweik said:


> Something like 8 or 9 months out of the year depending which part of the gigantic front line you are talking about, there was often a fairly low cloud ceiling which prevented high flying planes from seeing the battlefield or lower flying aircraft.



8 or 9 months of such weather - probably, but only in the northern part of the Eastern Front, from the Leningrad/Pskov region and up.


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## Schweik (Aug 6, 2020)

So clear skies over Moscow year round?


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## Dimlee (Aug 6, 2020)

Schweik said:


> So clear skies over Moscow year round?



So - not.


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## Schweik (Aug 6, 2020)

Right. So .. gloomy roughly 7 months out of the year? 6?

Average Weather in Moscow, Russia, Year Round - Weather Spark


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## Dimlee (Aug 6, 2020)

Something like that, but there are periods of sunny weather even in the winter when high pressure settles. I lived in Moscow for 10 years not counting many trips before and after. Sky diving season was early April to end October/early November, as I remember.

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## GregP (Aug 7, 2020)

The only turbocharged use of the Allison V-1710 in any but experimental installations was the P-38. In point of fact, the Curtiss XP-37 was both supercharged and turbosupercharged, but they only made 14 of them. The original XP-39 was turbosupercharged but, again, there was only the one airframe.

The Consolidated P-30 (PB-2) had a Curtiss V-1570 and was turbosupercharged, and I have heard people claim it had an Allison, but it didn't. They DID have a Vultee testbed aircraft for the Allison V-1710. Here is a Consolidated A-11, with Curtiss engine:






The Allison V-1710 testbed was the Consolidated XA-11A, but I have never found a pic of it. Just the standard P-30 and XA-11 (not XA-11A) with the Curtiss V-1570 engine ... some with turbosupercharger, and one with enlarged fin ... but that didn't have the V-1710.

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## wuzak (Aug 10, 2020)

GregP said:


> In point of fact, the Curtiss XP-37 was both supercharged and turbosupercharged, but they only made 14 of them.



Did you mean to say that there was an additional supercharger on the XP-37 and YP-37 other than the engine stage supercharger on the V-1710?

The XP-37 (1 made) and YP-37 (13 made) were turbocharged and supercharged the same way the P-38 was.


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## GregP (Aug 10, 2020)

Hi Wayne,

I said what I intended to say, and I said it clearly. The Curtiss XP-37 was both supercharged and turbosupercharged. How much more clear can it be?

The supercharger was integral with the auxiliary section and the turbosupercharger was external and fed the supercharger. They moved the cockpit to the rear to clear all the plumbing.

Allison V-1710 were built in many configurations. They were built as:

1) Normally aspirated:






Note the clear absence of the auxiliary-stage supercharger in this airship engine.

2) Supercharged:






Standard F-Series V-1710 above, with splined propeller shaft and integral supercharger in the auxiliary stage fed by the carburetor. The power section is the crankshaft and cylinders, the nose section is the prop shaft and associated gears. The auxiliary section contains the supercharger, the carburetor, the starter (not shown above ... there is a circular plate bolted one instead), the generator (same as starter above ... circular plate bolted on). So, this engine may well be able to run, but you can't start it! The round torus-shaped thing at the bottom rear is the water pump. The stainless line coming from the carburetor to the supercharger housing feeds fuel directly into the supercharger impeller.

3) Supercharged and turbosupercharged as in the P-38:





Note the turbocharger located in each nacelle boom right at the trailing edge of the wing. I haven't seen a pic of the P-38 setup outside of the P-38 with just the engine and the turbocharger assembly.

4) Turbo-compound:





Note the turbocharger in the auxiliary stage. The high-pressure air feeds the carburetor without an intercooler.

5) 2-stage supercharged:





Auxiliary supercharger stage has the carburetor and it feeds the supercharger impeller directly, without an intercooler.

6) Remote rear drive, as in the XB-42:





The contra-prop would be at the rear of the fuselage, with one V-1710 driving each prop.

7) A proposed V-3420 medium bomber with two V-3420s driving VERY larger propellers:





There are more configurations, but this covers some of the proposed applications.

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## Dash119 (Aug 10, 2020)

Schweik said:


> You mean supercharger not turbo right?


I think some of the confusion here may be in the nomenclature...

During this time period exhaust driven Superchargers were referred to as "Turbo-Superchargers". In modern parlance we just refer to them as "Turbochargers". On the Allison(s) in most P-38's there was an exhaust driven "Turbo-Supercharger" which fed the integral engine driven "Supercharger". So it was in essence a two-stage system with an intercooler between the two types of compressors.

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## Schweik (Aug 10, 2020)

GregP said:


> The only turbocharged use of the Allison V-1710 in any but experimental installations was the P-38. In point of fact, the Curtiss XP-37 was both supercharged and turbosupercharged, but they only made 14 of them. The original XP-39 was turbosupercharged but, again, there was only the one airframe.
> 
> The Consolidated P-30 (PB-2) had a Curtiss V-1570 and was turbosupercharged, and I have heard people claim it had an Allison, but it didn't. They DID have a Vultee testbed aircraft for the Allison V-1710. Here is a Consolidated A-11, with Curtiss engine:
> 
> The Allison V-1710 testbed was the Consolidated XA-11A, but I have never found a pic of it. Just the standard P-30 and XA-11 (not XA-11A) with the Curtiss V-1570 engine ... some with turbosupercharger, and one with enlarged fin ... but that didn't have the V-1710.



Really interesting but you missed my point - what I was trying to clarify was that you used the term 'turbocharger' seemingly in the context of the P-40 and / or P-39, when I think you meant just 'supercharger'...


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## Schweik (Aug 10, 2020)

Dash119 said:


> I think some of the confusion here may be in the nomenclature...
> 
> During this time period exhaust driven Superchargers were referred to as "Turbo-Superchargers". In modern parlance we just refer to them as "Turbochargers". On the Allison(s) in most P-38's there was an exhaust driven "Turbo-Supercharger" which fed the integral engine driven "Supercharger". So it was in essence a two-stage system with an intercooler between the two types of compressors.



I'm aware of the difference and the period terminology, though it does bear repeating.


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## GregP (Aug 10, 2020)

Hi Schweik,

If you go read my posts, I stated clearly that the only turbosupercharged application, other than experimentals and the very low-volume P-37, was the P-38.

The term "turbosupercharger," as used in WWII, is what we call a turbocharger today.

If you go up and look at the turbo-compound engine (#4) above, you can clearly see the turbo part at the rear, with the circle of turbine-like blades that the hot exhaust runs through to make it spin. It is connected via a solid driveshaft, to a compressor (the "charger" part) that feeds the integral engine supercharger impeller. So, there are two stages of boost, the compressor at the extreme rear operated by the exhaust gas and the integral supercharger operated by the crankshaft.


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## wuzak (Aug 10, 2020)

GregP said:


> Hi Wayne,
> 
> I said what I intended to say, and I said it clearly. The Curtiss XP-37 was both supercharged and turbosupercharged. How much more clear can it be?



Hi Greg,

It just stood out to me that you made a point of specifying turbocharging and supercharging for the P-37, but not for the P-38 or XP-39.

Just a case of me overthinking what you were saying.


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## wuzak (Aug 10, 2020)

GregP said:


> If you go up and look at the turbo-compound engine (#4) above, you can clearly see the turbo part at the rear, with the circle of turbine-like blades that the hot exhaust runs through to make it spin. It is connected via a solid driveshaft, to a compressor (the "charger" part) that feeds the integral engine supercharger impeller. So, there are two stages of boost, the compressor at the extreme rear operated by the exhaust gas and the integral supercharger operated by the crankshaft.



The turbocompound was based on the 2 stage supercharged engine. The auxiliary supercharger is driven by the engine via a fluid coupling.

The turbine is connected to the auxiliary supercharger and drives the entire engine. 

Unlike a turbocharger, there is no bypass of the turbine. The exhaust goes through the turbine all of the time.

The turbine for the turbo-compound V-1710 was an adaption from the larger C-series turbocharger, as used on the P-47.


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## GregP (Aug 10, 2020)

The engine shown above as 4) is identified in several references, including Vees for Victory as the V-1710-127 turbocompound engine. You can see that the exhaust is fed directly to the turbine, and the compressor feeds the carburetor. There is ALSO a coupling path to the crankshaft, but the exhaust comes out the turbine at the rear only.

The output of the rear compressor feeds the carburetor and the fresh air intake is between the turbine and the compressor, but there is ALSO a mechanical AND fluid coupling to the crankshaft, according to Vees for Victory.

It was a successful prototype, but the war was winding down and it never made production or flew, AFAIK. With exhaust gas temperatures of 1,750 - 1,825°F, the "state of the art" was being pushed, metallurgically, anyway. But we never got the chance to see how it would play out.


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## Schweik (Aug 10, 2020)

I don't want to beat it to death, I think you just made a typo when you were talking about P-40s etc. running "without their turbochargers". Maybe I read it wrong.


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## GregP (Aug 11, 2020)

More of a misunderstanding, likely due to my wording.

To me, running non-turbo can mean either the turbo is not operating or is not present. In the case of the P-39 and P-40, the turbocharger was not present, except for the turbocharger in the XP-39. In the case of P-38s running today (except for ONE unit that still runs them), the turbos are locked in stationary position, and so function only as an exhaust outlet. For the rest of them, the small intake below the trailing edge of the wing (see the Planes of Fame P-38J-20 below)






used to be the fresh air intake for the turbocharger. Since we aren't running the turbos, and most of the rest of them aren't either, they have been modified. The intake under the spinner is divided into 3 segments. The outer two section are oil cooler intakes and the center intake used to be fresh air for the intercooler.

Today, the center section is the carburetor fresh air intake and the original turbo fresh air intake is blocked off. If you aren't running a turbocharger, you don't need an intercooler. This thing is already expensive enough to operate!

The "we" above is the Planes of Fame Museum, not me. Hopefully that is clear.

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## Schweik (Aug 11, 2020)

Yes thank you! But they do still use the regular superchargers on the other Allisons, right?


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## Dash119 (Aug 11, 2020)

Since the Supercharger on the Allison, and for that matter the Merlin, is integral to the engine itself there is no way to bypass or disconnect it. Although I suppose that a highly modified tractor puller engine might eliminate the installation...


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## Schweik (Aug 11, 2020)

That's what I figured, just wanted to confirm.


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## MIflyer (Aug 11, 2020)

My friend Ward Duncan, who was maintenance chief of the 9th PRS, said he was a bit concerned about bypassing the usual turbo intake, since there was no provision for carb heat to take care of any icing. He was specifically talking about Glacier Girl.

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## GregP (Aug 11, 2020)

I probably could find out specifically about Glacier Girl given a bit of time but I am not worried. The owner does all his restorations the right way. I'm sure he has some provision for carb heat, especially seeing as how the prototype P-38 was lost to carb icing.

Nobody who actually flies his warbirds would leave that off, and the owner of THIS warbird flies it.


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## GregP (Aug 11, 2020)

Corect above, any Allison V-1710 is supercharged, assuming it is not an early dirigible engine, that is. I really don't know if any of the early dirigible engines have survived. I have personally seen maybe 150 Allisons, and have not seen one as yet. Perhaps one or possibly even more survives somewhere. The horsepower rating would likely be a bit less than 1,000 hp, if so but, if it IS a V-1710, at least the parts fit!

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## MIflyer (Aug 11, 2020)

While working on my 1978 Celica years ago found that the temperature switch that applied vaccum to an actuator that drew in hot air over the exhaust manifold was defective. In fact it had never been hooked up during dealer prep. I then consulted the manual and found that the system was designed to control the inlet air temp to the carb at 110F. As designed the Carb heat was always on! I would have been always driving in a desert. I wired in an electrical switch to actuate the carb heat when I thought it was necessary, just like I do in an airplane.


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## BiffF15 (Aug 11, 2020)

GregP said:


> I probably could find out specifically about Glacier Girl given a bit of time but I am not worried. The owner does all his restorations the right way. I'm sure he has some provision for carb heat, especially seeing as how the prototype P-38 was lost to carb icing.
> 
> Nobody who actually flies his warbirds would leave that off, and the owner of THIS warbird flies it.



Greg,

Which P38 still flies with its turbos operating?

Cheers,
Biff


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## GregP (Aug 11, 2020)

Hi Biff,

Seems like it is "Tangerine" out of Tilamook, but I could be mis-remembering that. Steve Hinton (as well as a few other folks around the P-38 world) would know, but I don't see him much these COVID days. Did see him last Saturday, but didn't ask this question at the time. I went to see Rob Patterson fly our F1U-1a Corsair in a demo and check out the GT 350 Mustang club that was visiting the museum that day (I drove my Mustang GT in).

Always nice to hear an R-2800 running, and great to see the Museum and Fighter Rebuilders guys again.

Next time I see him, I'll ask.

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## P-39 Expert (Aug 19, 2020)

Mike Williams said:


> Was there some kind of cooling issues during climb? Oil temps high? It would have helped if 3000 R.P.M. could have been used as well as the same boost as with level flight, for example 44" Hg. while climbing. I was hoping I could work up a 44" Hg./3000 rpm curve extrapolated from the Australian test but the 2600 R.P.M. used sort of complicates that notion.


Allison and the AAF increased combat power (3000rpm) limit from 5 minutes to 15 minutes in mid '42, about the same time that they finally got rid of the backfire screens. I don't know if the two were related but I suspect so. The new 15 minute limit greatly increased climb and ceiling in the tests since the rpm had to be reduced to 2600 after 5 minutes before mid '42. After mid'42 combat power (3000rpm) was used all the way up to service ceiling.

P&W had their combat power (2700rpm) limit increased from 5 minutes to 15 minutes at the same time. But their normal power of 2550rpm was so close to combat power (2700rpm) that it didn't make that much difference.


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## slaterat (Aug 28, 2020)

The tropical Spit V is generally considered the low point of the Spitfire in WW2. The basic Spit1/V just didn't adapt that well to tropicalization. Its not all to blame on the volkes filter either, (compare to the much cleaner installation on the Hurricane), as the tropical Spits nose was also enlarged for a larger glycol header tank. I think much of the same could be said for the P 40E, Kitttyhawk 1 as well. Its the low point of P 40 development as well. Its a thousand pounds heavier than a Tomahawk, barely faster with an air filter installed, with a pathetic rate of climb, all to get 6x.50 s in the wings that can't be fired under G , or they will jam.

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## PAT303 (Aug 29, 2020)

slaterat said:


> Its not all to blame on the volkes filter either



The trouble with the MkV is the extra weight and drag added wasn't offset by the increase in power. Compare the MkV to the MkIX, same air frame but two stage engine giving more power across a broader range. Personally I feel the RAF should have stayed with the 8 mg's harmonised at 200 meters with an increase in belt length and standardise on AP and incendiary with every 5th round a tracer.


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## GregP (Aug 30, 2020)

The P-40E gun jamming was corrected in summer/fall 1942, and the type caused an acceleration of improvements to the Bf 109E leading to the Bf 109F because it was fast and maneuverable. 

I'm not too sure if the pilots would have swapped the two extra guns and ammo for lighter weight or not seeing as how it wasn't going to help the performance above 15,000 feet by much anyway. In any case, they didn't get a vote. The difference in weight was about 760 pounds, not 1,000. Perhaps not a lot of difference, but 1,000 pounds is about 31.6% heavier than 760 pounds, so it also isn't insignificant. 240 pounds is roughly about like a second crewman in weight.


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## wuzak (Aug 30, 2020)

GregP said:


> The P-40E gun jamming was corrected in summer/fall 1942, and the type caused an acceleration of improvements to the Bf 109E leading to the Bf 109F because it was fast and maneuverable.



?????

If I understand your statement above, correctly the F was a response to the P-40?

The Bf 109F-1 was first in combat in October 1940, and the F-4 was in service in June 1941. The F was in development since 1939.

How did the P-40 have any influence on that?

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## SaparotRob (Aug 30, 2020)

wuzak said:


> ?????
> 
> If I understand your statement above, correctly the F was a response to the P-40?
> 
> ...


Cool nose art.


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## rochie (Aug 30, 2020)

wuzak said:


> ?????
> 
> If I understand your statement above, correctly the F was a response to the P-40?
> 
> ...


maybe because fragile British aircraft wouldn't of warranted improvements to the Bf109 E so it had to be an American type ?
i suppose a Nazi spy told them what was coming so they started a program of improvements for when the war started on Dec 7th 1941 !


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## GregP (Aug 30, 2020)

The Bf 109F was not a response to the P-40E. Simply, the P-40E was fast and maneuverable below about 15,000 feet. In North Africa, the Bf 109Es were found a bit wanting, and there were improvements made to the Bf 109E because, early in the war, North Africa / Med was an important theater. It was found the Bf 109E had reached about a development peak, and the "redesign" was underway before the P-40E, but wasn't moving nearly as quickly as it did after a strong appearance in North Africa. Popular aviation art shows a Bf 109E flying over a shot down P-40, but it wasn't wasn't always that way.

The P-40E was not the main reason for the redesign of the Bf 109E; the Bf 109F was under development before the P-40E appeared in late 1941. But it's appearance DID push the Bf 109F's priority up a bit. The Bf 109F development started in 1939, albeit slowly. Early prototypes used the DB 601N (1,159 HP or 1,175 PS). After Feb 40, the DB 601E (1,332 HP or 1,350 PS) was available for the Bf 109. The first two prototypes kept the trapezium wings of the Bf 109E with slightly reduced span, but the V23 had semi-elliptical wingtips.

If you look into it, they speeded up the Bf 109F almost exactly coincident with the introduction of the P-40E. So, right when the Bf 109E was getting a slight black eye, they completed all the Bf 109E upgrades that had been languishing or, more correctly, moving slowly, and got the Bf 109F into production.


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## rochie (Aug 30, 2020)

but the F-4 was in service 6 months before the P-40E, how can one variant influence another variant if it was entered into service after the one it was supposed to have influenced ?

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## Clayton Magnet (Aug 30, 2020)

rochie said:


> but the F-4 was in service 6 months before the P-40E, how can one variant influence another variant if it was entered into service after the one it was supposed to have influenced ?


The F-4 might have been, but the F-1 was in service in October of 1940. That's still the Battle of Britain, or the very tail end of it. Which predates the appearance of the Kittyhawk by more than a year

The arrival of the Kittyhawks was much closer to the introduction of the Gustav

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## rochie (Aug 30, 2020)

Clayton Magnet said:


> The F-4 might have been, but the F-1 was in service in October of 1940. That's still the Battle of Britain, or the very tail end of it. Which predates the appearance of the Kittyhawk by more than a year
> 
> The arrival of the Kittyhawks was much closer to the introduction of the Gustav


But it was supposed to have been the catalyst for the introduction of the F model were told


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## Vincenzo (Aug 30, 2020)

The Emil go out of production in June '41 (6 E-7/NZ) and i'm not sure if this were neaubau or umbau
in all 141 Emil were built in '41, with over 2,500 109 built that year
33 in january
28 in february
54 in march
20 in april 
0 in may
6 in june


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## Glider (Aug 30, 2020)

I admit to finding the thought that the P40 in any version at any time, drove or influenced the development on the Bf109 in any way totally weird. 

I suggest a cold bath for the believers and recommend that they think through the total lack of logic or evidence that even hints towards this before posting anything else


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## GregP (Aug 30, 2020)

Actually, I am just paraphrasing articles and things I've heard over the years. I can say that the 6 MG P-40E was a pretty good improvement over the earlier units, which sported two 50-cal and four 30-cal guns.

The Bf 109F was a general fuselage clean-up with a new spinner adopted from the Me 210, elbow-shaped supercharger intake, rounded fuselage, and a host of other small changes. There was a more aerodynamic oil cooler radiator and fairing, a new ejector exhaust, particularly on the left side where a metal shield was fitted to prevent exhaust from entering the supercharger intake, as wella s a new VDM propeller. Most importantly, while the rudder was slightly reduced in area, the fin was airfoiled to assist in keep the tail straight on takeoff and in flight. Note the airfoil was for a clockwise-turning propeller. This was NOT good if a counterclockwise-turning engine, such as a Hispano, was fitted.

But, all this was not moving very fast until late 1941.


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## Vincenzo (Aug 30, 2020)

GregP said:


> Actually, I am just paraphrasing articles and things I've heard over the years. I can say that the 6 MG P-40E was a pretty good improvement over the earlier units, which sported two 50-cal and four 30-cal guns.
> 
> The Bf 109F was a general fuselage clean-up with a new spinner adopted from the Me 210, elbow-shaped supercharger intake, rounded fuselage, and a host of other small changes. There was a more aerodynamic oil cooler radiator and fairing, a new ejector exhaust, particularly on the left side where a metal shield was fitted to prevent exhaust from entering the supercharger intake, as wella s a new VDM propeller. Most importantly, while the rudder was slightly reduced in area, the fin was airfoiled to assist in keep the tail straight on takeoff and in flight. Note the airfoil was for a clockwise-turning propeller. This was NOT good if a counterclockwise-turning engine, such as a Hispano, was fitted.
> 
> But, all this was not moving very fast until late 1941.



i think you need to read again that articles, the F was the main production version of 109 from late 1940


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## Clayton Magnet (Aug 30, 2020)

GregP said:


> Actually, I am just paraphrasing articles and things I've heard over the years. I can say that the 6 MG P-40E was a pretty good improvement over the earlier units, which sported two 50-cal and four 30-cal guns.
> 
> The Bf 109F was a general fuselage clean-up with a new spinner adopted from the Me 210, elbow-shaped supercharger intake, rounded fuselage, and a host of other small changes. There was a more aerodynamic oil cooler radiator and fairing, a new ejector exhaust, particularly on the left side where a metal shield was fitted to prevent exhaust from entering the supercharger intake, as wella s a new VDM propeller. Most importantly, while the rudder was slightly reduced in area, the fin was airfoiled to assist in keep the tail straight on takeoff and in flight. Note the airfoil was for a clockwise-turning propeller. This was NOT good if a counterclockwise-turning engine, such as a Hispano, was fitted.
> 
> But, all this was not moving very fast until late 1941.


By late 1941, the Bf 109F was fully developed, and had been so for some time. At that time, it was the Gustav that was being developed


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## GregP (Aug 31, 2020)

Hi Vincenzo,

Thanks for the correction. I can still find articles saying the Bf 109F was hurried up to address the P-40E in North Africa / Med, but now the dates are not making sense. Something somewhere seems to be a bit off, that's for sure. So, maybe I can shelf this one until I get time to look at it some more.

When I go back and read some of the things said in 1960 / 1970 books on the subject, some things seem a bit out of kilter.

Cheers.

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## rochie (Aug 31, 2020)




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## Vincenzo (Aug 31, 2020)

Just for info
the Kittyhawk fly their first mission the 28th December 1941 with the 3rd SAAF squadron
i've not checked but USAAF equivalent go in battle highly probably early in the month in the "Far East"


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## Glider (Aug 31, 2020)

GregP said:


> Actually, I am just paraphrasing articles and things I've heard over the years. I can say that the 6 MG P-40E was a pretty good improvement over the earlier units, which sported two 50-cal and four 30-cal guns.
> 
> .



Look at it from a German perspective. Your main fighter the 109E has reached the peak of its development and needs a serious redesign. You look around and you see :-

Spitfire - fully a match for your 109E and clearly being developed. You probably know that there is a Mk2 entering service and will have heard of 20mm cannon
P40 in its earliest form - not even close to a match for the 109E, lacking weapons, performance, protection, self sealing fuel tanks and belonging to a country that isn't in the war.

Which are you going to worry about?

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## pbehn (Aug 31, 2020)

Isnt the difference in a word develop and deploy. The P-40 obviously didn't change or force the deployment of a more advanced Bf 109 marque. However the LW had many places to send aircraft and was producing/developing several types so the question is where do you send your "E"s and "F"s?

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## wuzak (Aug 31, 2020)

pbehn said:


> Isnt the difference in a word develop and deploy. The P-40 obviously didn't change or force the deployment of a more advanced Bf 109 marque. However the LW had many places to send aircraft and was producing/developing several types so the question is where do you send your "E"s and "F"s?



Yes, that's what I was going to say.

The P-40E may have sped up the deployment of the Bf 109F to the Med, but not the model's development.

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## Stig1207 (Sep 1, 2020)

Jg27 had converted to the Bf 109F-4 before the P-40E turned up over the desert. The exchange rate (kills vs losses) favoured Jg27 since arriving in Africa with the Emil. As Pbehn noted, it was more likely that they recieved the Friedrichs when they did, because it was their turn; the Channel and Eastern fronts probably had higher priority.


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## Vincenzo (Sep 1, 2020)

I did some research on ww2.dk
there is (single engine) Fighter situation at 27th December '41, and if i miss nothing, there were no Emil, in fighter unit, in Africa that day so i suppose the the Kittyhawk and Emil never clashed

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## soaringtractor (Sep 3, 2020)

GregP said:


> Hi Soaringtractor,
> 
> Every country in WWII was nationalistic ... ALL of them. The British were no different than we were in that regard. Not sure the British lied about anything, but their flight reports generally limited the Allison to some lower boost than was used in combat while the Merlins in their tests were boosted to what WAS used in combat. That isn't exactly a lie since the test conditions were printed in the reports.
> 
> ...


I am just the messenger reporting the "facts" I have read !!!! And i tire quickly of the Brits arrogant attitude and constant badmouthing anything American. How would it have been IF "WE.." had of just stayed home with our Inferior equipment and troops and let the Brits fight the huns by themselves. IF "WE.." had England would be speaking German today !!! you are welcome.....Limeys !! !

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## GregP (Sep 3, 2020)

The Desert Air Force (DAF), also known chronologically as Air Headquarters Western Desert, Air Headquarters Libya, the Western Desert Air Force, and the First Tactical Air Force (1TAF), was an Allied tactical air force created from No. 204 Group RAF under RAF Middle East Command in North Africa in 1941 to provide close air support to the British Eighth Army against Axis forces. Throughout World War II, the DAF was made up of squadrons from the Royal Air Force (RAF), the South African Air Force (SAAF), the Royal Australian Air Force (RAAF), the United States Army Air Forces (USAAF) and other Allied air forces.

In October 1941, the Western Desert Air Forces had 16 squadrons of aircraft (nine fighter, six medium bomber and one tactical reconnaissance) and fielded approximately 1,000 combat aircraft by late 1941. By the time of the Second Battle of El Alamein (Oct – Nov 42), the DAF fielded 29 squadrons (including nine South African and three USAAF units) flying Boston, Baltimore and Mitchell medium bombers; Hurricane, Kittyhawk, Tomahawk, Warhawk and Spitfire fighters and fighter-bombers. There were over 1,500 combat aircraft, more than double the number of aircraft the Axis could field.

Jagdgeschwader 27 (JG 27) "Afrika" was a fighter wing of the Luftwaffe during World War II. The wing was given the name "Africa" for serving in the North African Campaign predominantly alone in the period from *April 1941 to September 1942*. Elements of JG 27 fought in every major theatre of operations in which the Wehrmacht operated.

Stab JG 27 was created in October 1939 and assigned two gruppen (groups) in the Phony War. The wing's first campaign was Fall Gelb, the battles of the Low Countries and France. In the second half of 1940 JG 27 received a third gruppe and fought in the Battle of Britain. In 1941 it returned to Germany then fought in the German invasion of Yugoslavia and Battle of Greece in April 1941. The wing was then separated with two gruppen sent to support Operation Barbarossa, the invasion of the Soviet Union in June 1941. I. Gruppe was sent to Italian Libya beginning JG 27s North African Campaign from mid-April 1941. It was joined by II. Gruppe which was withdrawn from the Eastern Front after les than two weeks and transferred to Africa. III. Gruppe joined the other gruppen in North Africa in late 1941. JG 27 fought as a complete wing in Africa and Battle of the Mediterranean, supporting the Siege of Malta, until December 1942. I. Gruppe returned to France and spent the rest of the war serving in the Defense of the Reich, Channel Front, and Western Front theaters. III. and the newly created IV. Gruppe remained operating in Yugoslavia and Greece until March 1944.

Don't tell me they never fought each other! We've had North Africa P-40 veterans speak at the museum!

I mentioned the Bf 109F initially because, at least for the U.S.A., our best planes went to the ETO, with a slight detour to North Africa at first. Perhaps the Germans didn't send their "new" Bf 109Fs to North Africa right away, I'm not sure and am not interested enough to research it at this time. But the timeframes (1941 - late 1942) certainly overlap, and there were very certainly Bf 109 - P-40 battles. I will not go so far as to say, Bf 109E - P-40E battles took place, because I don't know for sure at this time. But the timeframe is certainly there for Bf 109 E / F and P-40E.

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## Gen. MacArthur (Sep 3, 2020)

If i was a pilot in the dessert, i'd want to be flying a Spitfire. Better maneuverability and climb rate.However, the P-40E is a tough son of a gun. As a fighter bomber it is amazing. But if at 20,000+ feet in a dogfight against 109F's I'd want to be in a spitfire for sure!

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## GregP (Sep 3, 2020)

Welcome, General. Can't ever go wrong with a Spitfire, unless it is a long-range escort mission! Great plane, if ever there was one. They may have invented the term "Great plane" with the Spitfire in mind.







Of course, this is the famous Spitfire ALE ... not the ubiquitous Supermarine Spitfire Mk XVIII below:






Hey now, THAT's a fighter!

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## Stig1207 (Sep 4, 2020)

GregP said:


> Don't tell me they never fought each other! We've had North Africa P-40 veterans speak at the museum!
> 
> I mentioned the Bf 109F initially because, at least for the U.S.A., our best planes went to the ETO, with a slight detour to North Africa at first. Perhaps the Germans didn't send their "new" Bf 109Fs to North Africa right away, I'm not sure and am not interested enough to research it at this time. But the timeframes (1941 - late 1942) certainly overlap, and there were very certainly Bf 109 - P-40 battles. I will not go so far as to say, Bf 109E - P-40E battles took place, because I don't know for sure at this time. But the timeframe is certainly there for Bf 109 E / F and P-40E.



Vincenzo wrote that Bf 109E's and P-40E's *may not have* clashed over Africa, not that 109's and P-40's never fought each other  
It is certain though that the Emil's main opponents from April-September '41 were Hurricanes and Tomahawks; from about October or November '41 on it would be Friedrichs against Hurricanes and Tomahawks; from about the New Year Kittyhawks as well.
Not that any of it really matters, because the idea that the P-40E had any influence on the Bf 109F's deployment to North Africa, is not only thwarted by the timeline, but also that the DAF fighters were coming off second best against Jg27 before and after the P-40E showed up.


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## GregP (Sep 4, 2020)

Hi Stig1207,

True, he did say that. But Bf 109s and P-40s were in North Africa at the same time in 1941 and 1942, and they DID clash. I said that North Africa may not have been the most important front for either the Allies or the Axis and, from that, I infer that Bf 109Es were likely still present in North Africa in 1941 - 1942. The P-40E may have come out in fall 1941 and, from that, I infer they MAY have been present in North Africa in 1942, when JG 27 was still stationed there with Bf 109s. They may or may not have had the Bf 109F at that time, I can't say.

I have heard a P-40 pilot who flew in North Africa speak, though I did not exactly pay attention to what P-40 sub-type he was flying, and he did not specifically say which Bf 109 model he fought. I generally pay attention to the opponent subtypes if they are mentioned in a talk, and SHOULD pay more attention to own subtypes.

So, absolutely no insult to Vincenzo at all, but I know P-40s fought Bf 109s in North Africa. What I do NOT know is the specific models that fought each other. He could be right that the Bf 109F may not have fought the P-40E in North Africa ... I don't know. But the Bf 109 and P-40 absolutely did fight each other in North Africa. The P-40 fought in every front the U.S.A. was involved in plus most that the British were involved in, and some the Dutch were involved in, and a few others, too. It was still fighting when the war ended, despite being out of production at that time. The Bf 109 was still fighting when the war ended, too, though it was still in production at the time.

Had I been the Germans developing the Bf 109F at the time, I would have been much more concerned with fighting Spitfires than P-40s, as suggested above, because the Spitfires were much better than the P-40 at higher altitudes that were common in Europe. In North Africa, however, the P-40 was pretty good below 15,000 feet where the North Africa air war was largely being fought. What I was quoting was a reference that stated the P-40E contributed to higher priority being assigned to the Bf 109F than it had before the P-40E. The reference is an old one, and maybe the inference was that the tail fix might have been speeded up. I have seen other references say that the initial "fix" was external longitudinal braces riveted to the tail, but have never pursued the truth of it. Actually, the only tail fix I KNOW had external braces was the Typhoon. I now doubt the old reference was accurate about Bf 109F development being tied to the P-40E and backed off from that above ... but it could be accurate. Yes, the Bf 109F came out in 1940 and the P-40E came in 1941, but the Bf 109F also had crashes due to tail failure in dives (Feb 1941) after it was first delivered to operational units in January of 1941, and required some rear fuselage redesign that may or may not have been pushed ahead for any number of reasons. 

I doubt the P-40E was one of those reasons at this time since I think the Bf 109F was "sorted out" with regard to the tail fix before the P-40E was produced and made it to North Africa and became operational there.

Actually, if I go back and read some old books, such as Famous Fighters of the Second World War by William Green (1962), I can find a few things, though not many, in there I now believe to be false. Green states that in a vertical dive, the Spitfire could not stay with the Bf 109E. I think the Bf 109E had fuel injection and accelerated better initially in a vertical dive, but the Spitfire would catch it after the initial dive move was made. We KNOW the Spitfire has a higher critical Mach number than the Bf 109. So, I'm not surprised if an old reference is in error, and I should have paid more attention to it before posting above. It happens.

I am likely rambling now; it's late ... so I'll stop.  Cheers.

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## rochie (Sep 4, 2020)




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## rochie (Sep 4, 2020)

soaringtractor said:


> I am just the messenger reporting the "facts" I have read !!!! And i tire quickly of the Brits arrogant attitude and constant badmouthing anything American. How would it have been IF "WE.." had of just stayed home with our Inferior equipment and troops and let the Brits fight the huns by themselves. IF "WE.." had England would be speaking German today !!! you are welcome.....Limeys !! !


welcome aboard our little forum Mr president, and i'd like to thank you for the great advice on how to cure Covid with toilet cleaner


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## Vincenzo (Sep 4, 2020)

GregP i know my English is very bad
but again the Emil (Bf 109E) was retired from fighter unit in North Africa before of the Kittyhawk did their first mission
this is not a opinion is a fact
the Bf 109 clashed with the P-40 in North Africa? oh Yes, the Emil (109E) clashed with the Tomahawk, and the Friedrich (109F) clashed with Kittyhawk and Tomahawk, probably (i've not checked) the F clashed also with USAAF P-40 (Kittyhawk equivalent) after Operation Torch, the Gustav (109G) clashed with Kittyhawk and USAAF P-40 (Kityhawk equivalent)

edit developing the 109F the german were not concerned of P-40 because the F was developed before of they encountered the P-40,


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## rochie (Sep 4, 2020)

Vincenzo said:


> GregP i know my English is very bad
> but again the Emil (Bf 109E) was retired from fighter unit in North Africa before of the Kittyhawk did their first mission
> this is not a opinion is a fact
> the Bf 109 clashed with the P-40 in North Africa? oh Yes, the Emil (109E) clashed with the Tomahawk, and the Friedrich (109F) clashed with Kittyhawk and Tomahawk, probably (i've not checked) the F clashed also with USAAF P-40 (Kittyhawk equivalent) after Operation Torch, the Gustav (109G) clashed with Kittyhawk and USAAF P-40 (Kityhawk equivalent)
> ...


unfortunately we are wasting our time Vincenzo, you cannot change someones mind who is certain they are correct all of the time !


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## GregP (Sep 4, 2020)

Hi Vincenzo,

Your English is better than my Italian by far.

I am open to the fact that the Bf 109E might have been retired from North Africa before any P-40s arrived. What is your source for that and what date was the last Bf 109E removed from North African service? I'm pretty sure that information exists or we would not be having this discussion.


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## MIflyer (Sep 4, 2020)

Here is a page out of the Osprey P-40 versus BF-109 book. But note it only addresses USAAF aircraft. Did the RAF get P-40D/E into service in North Africa earlier than the USAAF? I have more or less assumed they did, because they had Tomahawks in service there but have seen no evidence of it.


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## Vincenzo (Sep 4, 2020)

MIflyer said:


> Here is a page out of the Osprey P-40 versus BF-109 book. But note it only addresses USAAF aircraft. Did the RAF get P-40D/E into service in North Africa earlier than the USAAF? I have more or less assumed they did, because they had Tomahawks in service there but have seen no evidence of it.



As already writed. the SAAF fly first mission with Kittyhawk in late december '1941,
the RAF fly first combat mission with Tomahawk in early june '41 (but over the Syria)



GregP said:


> I am open to the fact that the Bf 109E might have been retired from North Africa before any P-40s arrived. What is your source for that and what date was the last Bf 109E removed from North African service? I'm pretty sure that information exists or we would not be having this discussion.



last time on this, the Emil (109E) war retired before of Kittyhawk arrive not of any P-40, luckily all can see that i writed

Removed from fighter service not later of 27th september 1941, for ww2.dk


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## GregP (Sep 4, 2020)

Thanks, MIflyer! 

Looks like P-40s and Bf 109s clashed as early as 26 Jun 41, likely I./JG 27. Also looks like II./JG 27 likely got there 3 Oct 41 with Bf 109Fs and I./JG 27 re-equipped with Bf 109Fs by the end of the year.

I'd say it looks like we have non-U.S. P-40s of a type earlier than the E fighting with Bf 109Es as early as 26 Jun 41. They might have fought with Bf 109Fs before the end of 1941. Then it looks like P-40Fs were next in North Africa, at least from the timeline in this book. The 33rd FG was a P-40 unit but didn't get to North Africa until late 1942, but they did clash with Bf 109s often. From the above, they likely clashed with Bf 109Fs and possibly Bf 109Gs, too. it depends on when the Bf 109Fs in North Africa were being phased out with Bf 109Gs.

The documents I have say "Bf 109" and "ME 109," but do not include the subtype. One such document would be "AD-A194-042, Air Command and Staff College Student Report on the 33rd Fighter Group - Fire From the Clouds." The documents is about the 33rd FG in North Africa. An excerpt is shown below (page 17):






While there is more, note they call the Messerschmitts "ME 109s" and do not add the sybtype. But it DOES indicate that P-40s and Bf 109s clashed over North Africa. The Appendix has all the awarded victories of the 33rd FG, but not the aircraft type of the victim.

From Post #313 above, it seems rochie is guilty of exactly what he is accusing me of. 

A discussion is hardly ever a waste of time if there is back and forth in it. For the record, I have made my share of mistakes in here. Most of us have. My main mistakes are almost all in some casual reply late at night when I don't check my memory. I'd bet none of us are WWII scholars who memorize the war facts and stay up on it all the time. If I don't think about some aspect for several months, I tend to get fuzzy with the details, and I may not be alone in that. 

Mea culpa. Cheers.


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## XBe02Drvr (Sep 4, 2020)

rochie said:


> welcome aboard our little forum Mr president, and i'd like to thank you for the great advice on how to cure Covid with toilet cleaner


Careful, he might take that as a compliment.

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## rochie (Sep 4, 2020)

XBe02Drvr said:


> Careful, he might take that as a compliment.


very probably


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## rochie (Sep 4, 2020)

Greg.

not one person on here will deny that Bf 109's and P-40's did indeed fight each other over Africa and parts of Europe.

my post #313 was because you have subtlety changed your stance from "the Bf 109 F was developed as a direct result of the P-40 E (Kittyhawk I and IA)
and are now posting info about combat between *Bf 109's of any variant combating P-40's of any variant* at *any time frame*, rather than just put your hand up and say " yep ok i got that wrong, i should of checked before posting" or something similar.

i personally do not have the knowledge to make sweeping statements of fact about most ww2 events and refrain from doing so, because i know the vast knowledge of members will pick this up.

and with that i will butt out of this discussion
Karl

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## MIflyer (Sep 4, 2020)

Here is the previous page from that chronology. It shows Tomahawks versus BF-109 for the first time on 16 Jun 1941.




e

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## GregP (Sep 4, 2020)

Was it subtle? I thought I stated pretty clearly that I backed off from that since it appears the timeline for the P-40E didn't exactly support the original contention I posted. I was using an old reference that, in retrospect, seems incorrect. It said the P-40E contributed to speeding up the development of the Bf 109F ... but it seems rather clear that the Bf 109F was both developed and probably debugged (tail issues ...) before the P-40E was delivered and in general service.

I read an interview with Erich Hartmann once in which he said he had stayed with his Bf 109F as long as was possible because he thought it a better airplane than the Bf 109G. So, while other people around him were flying the G, he was flying his F until it could not be sustained. 

That made me wonder how many serviceable E models soldiered along after the F came out, particularly in a backwater theater such as North Africa. When a new model comes out, I'm not too sure that servicerable older models were necessarily rotated out immediately just because a new model was available. Seems more likely they remained in use until they needed major service of some kind that would remove them from the duty roster anyway. In the case of the U.S.A., we sent "war weary" older fighter to the training bases so new pilots could fly them. If they were older models but not yet "war weary," they generally stayed in service. Perhaps Germany did the same? Seems to me like good use of the resources.

But, I am a fan of the airplanes themselves, not necessarily the actual WWII chronological operation of them. I help with old airplane restoration, mostly old military airplanes. That doesn't necessarily translate into intimate knowledge of the timeframe of subtype operations. I have a pretty decent timeline for U.S. airplanes, but not a quite so detailed one for axis airplanes. Perhaps the "social distancing" during COVID is a good time to generate some of that ...

Here's a sort of a start at it attached.

Cheers, rochie.

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## MIflyer (Sep 4, 2020)

I believe the Germans sent the older models, like the E, to allies as well as using them for training. A couple of RAF Mustang Mk I's hit a German training base and among the airplanes they found there was a 109E, which they shot down. I recall some 8th AF fighters encountering a 109E as well.

I think the 109F probably was built in response to the Spit Mk V, although some careful review of the timelines would be needed to confirm that. The 109G added power and heavier armament to the 109F and given the small size of that airframe, those improvements were not without drawbacks. 

I suspect that if the Germans had designed a fighter to better fight the P-40 in its best environment it would look more like an FW-190.


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## tomo pauk (Sep 4, 2020)

MIflyer said:


> ...
> I think the 109F probably was built in response to the Spit Mk V, although some careful review of the timelines would be needed to confirm that.
> ...



Bf 109F was probably built as a response to Bf 109E being awash with lumps & bumps, that hurt both speed and range. 
The Spitfire V was later in service than Bf 109F.

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## Shortround6 (Sep 4, 2020)

I think the whole idea that plane *A *was built in response to plane *B* is one of the greatest myths of aviation writing about WW II. 

The 109F was starting service trials in the fall of 1940, the BoB was barely over. actual work on it started when??? Spring or summer of 1940? If Spring Spitfire Is barely had constant speed props on their Merlin III engines. 

The P-40D/E was ordered in the summer of 1940, it didn't fly until the summer of 1941. 

The F6F Hellcat was ordered in the summer of 1941, well before the F4F ever encountered an A6M2. 

The F8F was started well before the first Kamikaze attack (at least and organized planned kamikaze attack) was ever performed by the Japanese (intentional crash by wounded pilot or crippled plane excepted).
The Nakajima N1K1-J first flew about *9 months* *before* the Japanese encountered the F6F Hellcat. 

The list goes on and on. Granted some planes may have had their priorities shifted a bit but to design and build even a new variant of a plane often took months, a new plane took two to 3 years. There was a lot of concurrent/overlapping development going on. 

They were trying to stay ahead of what the enemy might bring out *next. *Designing a plane to counter what your enemy already was bringing into service meant you were already 2-3 years behind.

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## MIflyer (Sep 4, 2020)

One of the things that amuses me now is something I read back in the early 60's. It said that once they had a flyable Zero in their hands and its test results, Grumman worked to reduce the weight in the F6F.

In reality Grumman yanked the R-2600 used in the F6F prototype and replaced it with the R-2800, which was heavier but a lot more powerful. Grumman did not try to out-Zero the Zero; they literally overpowered it.

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## SaparotRob (Sep 4, 2020)

Shortround6 said:


> I think the whole idea that plane *A *was built in response to plane *B* is one of the greatest myths of aviation writing about WW II.
> 
> The 109F was starting service trials in the fall of 1940, the BoB was barely over. actual work on it started when??? Spring or summer of 1940? If Spring Spitfire Is barely had constant speed props on their Merlin III engines.
> 
> ...


Don’t you just hate it when he points out everything you know is wrong?


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## Vincenzo (Sep 4, 2020)

Luftwaffe single engine fighter unit in Africa
I/JG27 from 21/4/41 to 2/10/42, and again from 25/10/42 to 13/11/42. Bf 109 Emil to before of 27/9/41, after Bf 109 Friedrich (-4), from 25/10/42 Bf 109 Gustav (-2)
7/JG26 from 14/6/41 to 24/9/41. Bf 109 Emil, afaik the only tropical Emil was E-7/Trop
II/JG27 from 24/9/41 to 6/12/42. Bf 109 Friedrich (-4), since late 10/42 also Gustav (-2)
III/JG27 from 6/12/41 to 12/11/42. Bf 109 Friedrich (-4)
III/JG53 from 8/12/41 to 17/12/41 (the 8/JG53 to 22/12/41) and again from 24/5/42 to 27/10/42, and again from 9/11/42 to 30/11/42. Bf 109 Friedrich (-4), from 9/11/42 Gustav (-4)
Stab/JG27 from 10/12/41 to 13/11/42. Bf 109 Friedrich (-4)
6/JG3 from 7/4/42 to 26/4/42. Bf 109 Friedrich (-4)
10/JG27 from 5/5/42 to 1/9/42. Bf 109 Friedrich, Jabo unit
10/JG53 from 12/6/42 to 31/8/42. Bf 109 Friedrich, Jabo unit
III/JG77 from 26/10/42 to 7/5/43. Bf 109 Friedrich (-4) and Gustav (-2), only Gustav (-2) from January '43, from April '43 Gustav (-4 &-6)
I/JG77 from 27/10/42 to 7/5/43. Bf 109 Friedrich (-4) and Gustav (-2), only Gustav from 15/12/42, from March '43 get also -4, from April also -6 and retired the -2
Stab/JG77 from 3/11/42 to 8/5/43. Bf 109 Gustav (-2), from March '43 -4 & -6 from May '43 only -6
II/JG53 from 9/11/42 to 9/5/43. Bf 109 Gustav (-2&-4) from January '43 only -4 from March '43 also -6
Stab/JG53 from 9/11/42 to 30/4/43. Bf 109 Gustav (-2), from February '43 -4, from March '43 also -6
II/JG51 from 14/11/42 to 11/2/43, again from ?/2/43 to 19/4/43. Bf 109 Gustav (-2), also -1 from December '42 to February '43, from 2/43 also -4, -6. This had 5 Anton-3 and 4 Anton-2 Fw 190 but were retired in December '42.
11/JG2 from 15/11/42 to 1/2/43. Bf 109 Gustav
II/JG2 from 20/11/42 to 15/3/43. Fw 190 Anton (-2& -3), from December '42 also -4 & -5
11/JG26 from 24/11/42 to 31/12/42. Bf 109 Gustav (-1&-4)
I/JG53 from 25/11/42 to 30/4/43. Bf 109 Gustav (-2), from December also -4, from March also -6 and -2 retired
II/JG77 from 13/12/42 to 7/5/43. Bf 109 Gustav (-2), from February '43 also -6, from March '43 also -4, -2 retired in April '43. Had also a few (6) Friedrich in the December/January (5 moved to other unit and one loss not enemy related)

data from ww2.dk my elaboration

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## eagledad (Sep 4, 2020)

Vincenzo said:


> I did some research on ww2.dk
> there is (single engine) Fighter situation at 27th December '41, and if i miss nothing, there were no Emil, in fighter unit, in Africa that day so i suppose the the Kittyhawk and Emil never clashed



Hello

I believe you are correct that no _fighter_ Emils clashed with Kittyhawks, but it appears that an E (Bf-109E-7/U3 ?) of 2(H)14 did. The E-7/U3 was a tactical recon version carrying two cameras. (Messerschmitt Bf-109 A-E by Radinger & Schick, page 96). 
On 14 March 1942, a Me-109E-7 (WNr 5278) was shot down by a P-40. On the same day, 2 Kittyhawk I's of RAF 112 squadron claimed 1 Bf-109, and 2 Kittyhawk I's of RAAF 3 squadron also claimed a Bf-109. (Mediterranean Air War volume 2, page 60) Whether any of the 2 claims was the E-7 or not, I do not know, as there is not enough data to make a definite connection. However, only 1 Messerschmitt was lost that day, and the 2 Kittyhawk claims were the only Messerschmitt's claimed that day.

Another E-7 was shot down by 3 Tomahawks of 5 SAAF Squadron on 28 May, 1942.

It appears that the E was used as a tac recon plane through at least the middle of 1942 in North Africa, as one was shot down by Flak in June (MAW pg 119).

FYI

Eagledad

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## MIflyer (Sep 4, 2020)

Well, the Spit IX WAS built in response to the FW-190. The Merlin 60 series two stage engine was developed for the high altitude Wellington and the Welkin high altitude fighter, and those two aircraft were developed in response to the Ju86P and R. As it turned out, that whole line of development for both sides was a waste of time, since once you got that high there was not much you can do. Bombloads were trivial, accuracies were terrible, and a strange and unexpected phenomena called "clouds" interfered with photographic recon over Europe.

But stick that engine on a Spit V and look out Focke Wulfs! And stick it on a Mustang MkI and you get Goring saying, "We have lost the war."

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## emu27 (Sep 4, 2020)

> These are the performances the Brits like to keep quiet as it destroys all their lies, hype and Bullshit about the Allison engine whether used in the P40 or the early Mustangs !! ! Facts of history coming to light !!!!!


Take a Bex and have a good lie down my boy. The Allison had it's strengths and weaknesses, as did the Merlin. The RAF pilots loved the Allison P-51, compared to the Merlin it was far better in the low/medium altitude role, gave better mileage as the revs could be reduced lower than a Merlin, was more robust, in fact they pulled the automatic boost control out and ran the engine full throttle at sea level (72 inches - War Emergency rating at the time was 56 inches) for as long as 20 minutes without harm to the engine, 1,500 hours between bearing failures compared to 5-600 on the Merlin. The Merlin was mechanically a complicated engine, twice as many parts as an Allison, and not given to abuse, but the Merlin transformed the -51 into the bomber escort for which it is famed. The RAF Allison -51's were still flying operations on the last day of the war. Such was the RAF experience flying them on Rhubarb raids the Northwest African Strategic Air Force and others wanted the aircraft to remain in production alongside the Merlin version.

Initially the US forces had no interest in the -51, in the US conference to select aircraft types to proceed for production the -51 didn't even make the list, and the two aircraft given the US by the Brits sat on the ramp unused. The Allison as used in the -38 undeniably had problems in the European theatre, brought about by cold at altitude.

*sid327*, re your comments.

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## PAT303 (Sep 5, 2020)

MIflyer said:


> Well, the Spit IX WAS built in response to the FW-190.



I don't believe that at all, they had the two speed 20 series in the Spit before the FW190 ever entered service, the 60 series engine was the natural development of that, FW190 or not the Spit was getting up engined as the war went on.


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## Shortround6 (Sep 5, 2020)

When was the Spitfire III trialed with a two stage engine? or was it?

When were plans made to build the MK VII Spitfire? Or the MK VIII?
Not when they first flew but when were plans started to build the prototypes. 

Development and production of the MK IX may certainly have been speeded up to counter to the FW 190.


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## DerAdlerIstGelandet (Sep 5, 2020)

soaringtractor said:


> I am just the messenger reporting the "facts" I have read !!!! And i tire quickly of the Brits arrogant attitude and constant badmouthing anything American. How would it have been IF "WE.." had of just stayed home with our Inferior equipment and troops and let the Brits fight the huns by themselves. IF "WE.." had England would be speaking German today !!! you are welcome.....Limeys !! !



And one more arrogant insulting post like that and you can post somewhere else.

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## GregP (Sep 5, 2020)

Wow Vincenzo, nice post!


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## MIflyer (Sep 5, 2020)

Actually the RAF and everyone else gave up on single engined fighters with less than at least 2000 cu In quite early. The new airplanes, Typhoon, Whirlwind, Tornado, P-38, P-47, XP-49, P-61, F4U, XF5F, F6F, Ki 61, FW-190, all had much bigger engines than the fighters of 1939 or two of them. And they were going to keep going up from there, too, with the XP-58, XP-75. The Brits considered the Spitfire to be "done" and planned to drop production. The Typhoon and similar sized airplanes were the future.

Then Sir Hooker came along and showed how to turn the SMALLEST DISPLACEMENT front line engine of the war (note: even the A6M3 had 1700 cu in) into a game changing war winner.

By the way, there is a HUGE difference between a two speed supercharged engine and a two speed two stage supercharged engine.

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## GregP (Sep 5, 2020)

Merlin 2-stage engine shown below with a few labels I inserted. This is a display engine because the distributor doesn't seem to have any plug leads coming out of it ... maybe they're just black and not obvious to me. I think this is from a museum in Denver, CO. Nice display.

Also not really sure if the cooler unit is technically an aftercooler or an intercooler. It cools the air after it emerges from a compression unit, so it is technically an aftercooler, and it cools the air before it enters the engine intake, so it is technically an intercooler. I'll stick with WWII terminology and stay with intercooler.


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## Snautzer01 (Sep 5, 2020)

DerAdlerIstGelandet said:


> And one more arrogant insulting post like that and you can post somewhere else.


Here here


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## wuzak (Sep 6, 2020)

Shortround6 said:


> When was the Spitfire III trialed with a two stage engine? or was it?



Some time in 1941.




Shortround6 said:


> When were plans made to build the MK VII Spitfire? Or the MK VIII?



The Mk VII and MK VIII were essentially the same aircraft, the VIII having standard wing tips and the VII extended wing tips.

The planning for these probably started when Hives of Rolls-Royce suggested using the 60 series, originally intended for a high altitude Wellington, into the Spitfire. And likely before the Spitfire III flew with the Merlin 61, the III serving as a prototype of sorts.




Shortround6 said:


> Development and production of the MK IX may certainly have been speeded up to counter to the FW 190.



The IX was quickly brought into production due to the Mk V being less competitive in mid to late 1941 and early 1942, due to the appearance of the Bf 109F-4 and Fw 190A.

This was supposed to be the interim solution until the definitive Mk VIII arrived.


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## PAT303 (Sep 6, 2020)

Shortround6 said:


> When was the Spitfire III trialed with a two stage engine? or was it?
> 
> When were plans made to build the MK VII Spitfire? Or the MK VIII?



The MkIII's design was in response to what was learned during the BoB, the MkVIII and MkXIV were based off the MkIII fuselage, the big advantage the FW 190 had over the MkV's was it's rate of roll and outright speed, the MkIII's streamlined curves and clipped wings addressed that.

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## wuzak (Sep 6, 2020)

PAT303 said:


> The MkIII's design was in response to what was learned during the BoB, the MkVIII and MkXIV were based off the MkIII fuselage, the big advantage the FW 190 had over the MkV's was it's rate of roll and outright speed, the MkIII's streamlined curves and clipped wings addressed that.



Except that the Spitfire III flew months before the Battle of Britain.

Some parts of the Mk III design never made it into production, including an improved radiator duct design.


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## PAT303 (Sep 6, 2020)

wuzak said:


> Except that the Spitfire III flew months before the Battle of Britain.



That's true, it first flew in March 1940 but the Air Ministry would not allow production of MkI-II's to stop to produce it, the plane instead became a development test bed, the prototype flew with both the two speed Merlin XX and the two stage Merlin 60.


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## wuzak (Sep 6, 2020)

PAT303 said:


> That's true, it first flew in March 1940 but the Air Ministry would not allow production of MkI-II's to stop to produce it, the plane instead became a development test bed, the prototype flew with both the two speed Merlin XX and the two stage Merlin 60.



Actually, it lost out to the Mk V, which was the Mk II with the Merlin 45. The Mk V would not interrupt production, whereas adopting the Mk III would. Plus the Merlin XX was needed elsewhere.


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## Shortround6 (Sep 6, 2020)

The FW 190 doesn't show up in combat until Aug of 1941 according to some accounts, It takes several weeks for it to show that it is NOT a leftover Hawk 75 or other ex French radial engine fighter. 

SO at what point did the British stick the Merlin 60 in the old MK III airframe and/or _start_ work on the MK VII/VIII (engine mounts, new radiators and ducts/housings) four bladed prop, etc. that wound up being able to be fitted to the MK V airframe with little trouble? 

Was the MK IX more of a "we can't wait for the MK VIII, do something NOW" or were both the MK VIII and MK IX replies to the Fw 190? 
A lot easier to do a lash up like the MK IX if a lot of the bits and pieces are already in the works.


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## wuzak (Sep 6, 2020)

Shortround6 said:


> The FW 190 doesn't show up in combat until Aug of 1941 according to some accounts, It takes several weeks for it to show that it is NOT a leftover Hawk 75 or other ex French radial engine fighter.
> 
> SO at what point did the British stick the Merlin 60 in the old MK III airframe and/or _start_ work on the MK VII/VIII (engine mounts, new radiators and ducts/housings) four bladed prop, etc. that wound up being able to be fitted to the MK V airframe with little trouble?
> 
> ...



The conversion of the Mk III to the Merlin 61 engine started in early 1941, with its first flight in September 1941. 

The Mk IX was the interim design that was brought about, in part, by the Fw 190. The Mk VII and VIII were in development before the Fw 190 appeared.


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## PAT303 (Sep 7, 2020)

Shortround6 said:


> British stick the Merlin 60 in the old MK III airframe



New air frame you mean, the MkV was the old one that became the MkIX.



Shortround6 said:


> Was the MK IX more of a "we can't wait for the MK VIII, do something NOW"



A more accurate description would be we have lots of MkII air frames so lets stick Merlin 45's in them and make them MkV's, then take all those MkV's air frames and stick the 60 series in them and make them MkIX's.


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## PAT303 (Sep 7, 2020)

wuzak said:


> The conversion of the Mk III to the Merlin 61 engine started in early 1941, with its first flight in September 1941.



The was also a MkI air frame converted to MkIX spec first flown in Jan 1942


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## Shortround6 (Sep 7, 2020)

PAT303 said:


> New air frame you mean, the MkV was the old one that became the MkIX.


 I meant the old MK III airframe that held a Merlin XX.

It shows the British were thinking of sticking the Merlin 60 (series) engine in the Spitfire airframe _before_ they encountered the Fw 190 in combat. 

so in Aug of 1941 they already had a pretty good idea of what was needed (new parts and the arrangement of parts). They did need to figure out any handling issues and any differences between the one-off MK III and whatever production version/s they wanted to build like the MK VII and VIII. 
Yes it turned out they could stick the Merlin 61 into the old airframes with suitable modifications. 
Yes the MK IX was in response to the FW 190 in order to get numbers up quickly.
But the two stage Merlin in a Spitfire airframe was not a response to the FW 190, it was going to happen anyway. Exact timing and numbers of each type produced may well have been different.

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## Wawny (Sep 10, 2020)

MIflyer said:


> I have no idea where I found this item. I do not even recall downloading it and found it by accident today while looking for something else. In case y'all have not seen it, here it is. Some of the results of this fly-off competition are quite predictable but others are not. I wonder how a P-40F would have fared.
> 
> View attachment 588144

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## Wawny (Sep 10, 2020)

MIflyer said:


> I have no idea where I found this item. I do not even recall downloading it and found it by accident today while looking for something else. In case y'all have not seen it, here it is. Some of the results of this fly-off competition are quite predictable but others are not. I wonder how a P-40F would have fared.
> 
> View attachment 588144


Flt Lt Wawn was my dad. He flew Spitfires in Britain 452 Sqn RAAF, and P40's at Milne Bay, PNG in 76 Sqn RAAF.
He also flew trials flying the Kittyhawk against a reassembled Hap/Zero at Eagle Farm 1943, (now Brisbane airport ).
During the Spitfire trial, he put a 15° bend in the tail during the manoeuvres. He didn't find that out until the 80's.
I have a copy of the original document.

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## P-39 Expert (Sep 10, 2020)

Attachment sounds pretty accurate. Remember the Spitfire had that Volkes filter that was a performance drainer.


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## MIflyer (Sep 10, 2020)

I have the Spitfire Vs. "Mk 2 Zero" report and perhaps I should post it in a separate dedicated thread.

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## soaringtractor (Sep 10, 2020)

GregP said:


> The P-40 had one of the best roll rates for an American fighter. It didn't turn as well as the P-36 with the radial engine, but it also wasn't a slouch. Being built to a different standard, it was heavier and didn't climb as well as a Spitfire, but this is the first time I have seen a claim that it was as good in a dogfight at 16,000 feet and below.
> 
> This goes a long way toward explaining why P-40s in North Africa did well against Bf 109Es. They were fighting much lower than they were in the ETO. I already knew they were fighting lower, but did not suspect they were as good as a Spitfire V at those altitudes. I also am not taking that at face value, but it DOES elevate the P-40 a bit in perceived capabilities.


One has to remember here that the shitfire Mk V was also a single stage supercharged engine, although it did have a second speed to turn the blower a little faster at altitude. Why it was not surprising the Packard V1650-1 when installed in the 1311 P40F & L's did not improve the performance of the P40 !!! People seem to "forget" that only about 25% of the merlins produced were the later slobbered and drooled over 60 series HIGH ALTITUDE versions used in the Mk IX MK VII & VIII's.......only 5656 of those made out of the 20,000 shitfires made !!! The majority of WW II Merlins were the 20 to 50 series SINGLE stage supercharger, most having the second speed. ie ALL Mk BI and BIII lancaster, ALL hurrycanes, most Mosquitos and shitfires used this early version of the merlin !!! The Lancaster and Hurrycane NEVER received the LATER 60 series High altitude merlins !!! Them ol facts of history raising their ugly head....AGAIN !!!!


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## P-39 Expert (Sep 10, 2020)

MIflyer said:


> I have the Spitfire Vs. "Mk 2 Zero" report and perhaps I should post it in a separate dedicated thread.


PERHAPS YOU SHOULD JUST POST IT NOW!!

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## Greyman (Sep 10, 2020)

P-39 Expert said:


> PERHAPS YOU SHOULD JUST POST IT NOW!!



A lot of discussion on that subject / test here: Japanese Zero vs Spitfire vs FW 190

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## Clayton Magnet (Sep 11, 2020)

soaringtractor said:


> One has to remember here that the shitfire Mk V was also a single stage supercharged engine, although it did have a second speed to turn the blower a little faster at altitude. Why it was not surprising the Packard V1650-1 when installed in the 1311 P40F & L's did not improve the performance of the P40 !!! People seem to "forget" that only about 25% of the merlins produced were the later slobbered and drooled over 60 series HIGH ALTITUDE versions used in the Mk IX MK VII & VIII's.......only 5656 of those made out of the 20,000 shitfires made !!! The majority of WW II Merlins were the 20 to 50 series SINGLE stage supercharger, most having the second speed. ie ALL Mk BI and BIII lancaster, ALL hurrycanes, most Mosquitos and shitfires used this early version of the merlin !!! The Lancaster and Hurrycane NEVER received the LATER 60 series High altitude merlins !!! Them ol facts of history raising their ugly head....AGAIN !!!!



Please show us on the doll where the bad Merlin engine touched you...
Seriously, what is your problem?

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## Clayton Magnet (Sep 11, 2020)

soaringtractor said:


> Why it was not surprising the Packard V1650-1 when installed in the 1311 P40F & L's did not improve the performance of the P40 !!!


Or perhaps maybe the P-40 airframe had reached the end of its useful development potential?

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## BiffF15 (Sep 11, 2020)

Clayton Magnet said:


> Or perhaps maybe the P-40 airframe had reached the end of its useful development potential?



I think he was introduced to the movie, "Das Boot"...

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## Shortround6 (Sep 11, 2020)

Perhaps he was repeating the often told myth that the P-40F was slower than a P-40E???
It rather depended on altitude which the myth tellers leave out. The P-40E was faster (by 5-15mph ) at altitudes below 15,000ft. However the F was 30mph or more faster at 20,000ft and at higher altitudes the difference just grew greater. 

http://www.wwiiaircraftperformance.org/P-40/P-40_Tactical_Planning_Characteristics.jpg

Basically the P-40F traded a bit of speed (without over boosting either engine) under 15,000ft for around 5,000ft of operational ceiling. 

The anti Merlin crowd likes to seize on the difference in speed and ignore the difference in altitude capability.


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## GregP (Sep 11, 2020)

Is there an "anti-Merlin crowd?" I definitely see an anti-Allison crowd, but the Merlin was and IS a great engine, and it's pretty hard to dispute that with facts. If there IS an anti-Merlin crowd, I'm not in it. 

I still wonder why nobody made an adapter and put the Merlin 2-stage supercharger section onto and Allison power section, if only to see how it would perform. If it did well, and it should have ... that alone might have fueled the development funds for a home-grown integral Allison 2-stage instead of the Auxiliary stage unit that was eventually developed.

The P-40F'L was a bit better a bit higher up than the Allison P-40, but it wasn't enough better to close the performance gap between the P-40F/L and a Bf 109 / Fw 190 and make the P-40F/L a player up there, unless I'm missing something. The P-40F/L certainly LOOKED better without the carb scoop on top of the cowling, and were worthy P-40 variants. If I am not mistaken, the demand for Merlins made parts for the Merlins in the P-40F/L units hard to come by for the P-40F/L units, and at least 70 P-40Fs were converted to P-40R-1s using Allison V-1710-81s of 1,360 hp. It wasn't because the Allisons were better or worse, but because they were available and sustainable.

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## Clayton Magnet (Sep 11, 2020)

GregP said:


> Is there an "anti-Merlin crowd?"



See Monsieur "flying farm equipment" and his numerous posts above


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## rochie (Sep 11, 2020)

only anti Rolls Royce Merlin crowd.

Packard Merlins were more powerful, reliable, production line manufactured to tighter spec's and tolerances rather than individually hand fettled from chunks of low grade aluminium and cast iron

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## GregP (Sep 11, 2020)

My mistake, I thought flying farm equipment was an army of one, a legend in his own mind.

Yeah, them Rolls-Royces are awful. It's not as if they have a reputation for quality or anything like that, is it? 

A quick check of Spitfire production tells me there were:
1) 9,300 single stage Merlin Spitfires (54.7%) of total: 1 prototype, 1,569 Mk I, 921 Mk II, 2 Mk III, 229 Mk IV, 6,478 Mk V, and 100 Mk VI.
2) 9,024 two-stage Merlin Spitfires (44.3% of total):150 Mk VII, 1,652 Mk VIII, 6,126 Mk IX, 26 TR-9, and 16 PRX.
3) 2,043 Griffon Spitfires (10.0% of total): 100 Mk XII, 957 Mk XIV, 300 Mk XVII, 225 PR XIX, 120 Mk 21, 287 Mk 22, and 54 Mk 24.

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## Shortround6 (Sep 11, 2020)

GregP said:


> The P-40F'L was a bit better a bit higher up than the Allison P-40, but it wasn't enough better to close the performance gap between the P-40F/L and a Bf 109 / Fw 190 and make the P-40F/L a player up there, unless I'm missing something. The P-40F/L certainly LOOKED better without the carb scoop on top of the cowling, and were worthy P-40 variants. If I am not mistaken, the demand for Merlins made parts for the Merlins in the P-40F/L units hard to come by for the P-40F/L units, and at least 70 P-40Fs were converted to P-40R-1s using Allison V-1710-81s of 1,360 hp. It wasn't because the Allisons were better or worse, but because they were available and sustainable.



You are correct the Merlin in the P-40F/L wasn't enough to close the gap, but it was the best the US could do at the time (prepare for and execute the NA invasion and then Italy) and it may have done it's job adequately. The US may have failed to follow the British lead in allowing higher boosts at low altitude? 
One story claims the US failed to acquire enough spare Merlins and the higher than expected consumption of engines in North Africa (low mounted supercharger intake?) just compounded the problem. I don't know if the Americans even came close to getting the 3000 engines they were supposed to get under the _initial _agreement. Whatever they didn't get went into British aircraft. Subsequent agreements or modifications to agreements don't seem to get much expose.


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## GregP (Sep 11, 2020)

Hi Shortround,

You make a very good point about the P-40F being not enough to close the gap, but better than the Allison units at 20,000 feet. If you were going to fight at 20,00 feet in a P-40, you'd want a P-40F/L. No doubt about it.

I would really like to have seen a P-40Q with a Merlin 2-stage in it ... but it was never to be seen. To my eye, the 2nd and 3rd P-40Qs look quite a bit like Spitfire 24s and at gross weight, were a bit lighter than the Spitfire 24 (9,000 lbs for the XP-40Q-2 and 9,900 lbs for the Spitfire 24). It is a tantalizing "might have been," but was not to be.

XP-40Q-2:






Spitfire 24:






Nice cannons, huh? Both look good ... at least to me.

Let's see, they made 54 Mk 24s and 3 XP-40Q, but only two with bubble canopies. So, neither one was exactly "mass produced." In the case of the Spitfire 24, it was probably a combination of the end of the war in sight and jets showing what they could do. We've discussed the XP-4Q before ... but it still is a good-looking and good-performing airplane to contemplate.

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## Clayton Magnet (Sep 11, 2020)

GregP said:


> Nice cannons, huh?



Something seems off about that Spitfire. Why are the cannons so far apart? And didn't the Mk.24 use the short barreled Mk.V Hispano? 
Also, why are there 4 cannons, and 4 machine guns?


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## Greyman (Sep 11, 2020)

Clayton Magnet said:


> Something seems off about that Spitfire. Why are the cannons so far apart? And didn't the Mk.24 use the short barreled Mk.V Hispano?
> Also, why are there 4 cannons, and 4 machine guns?



Photoshopped image, Original here:
Private Supermarine Seafire XVII photo by Stephen Fox

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## Clayton Magnet (Sep 11, 2020)

Greyman said:


> Photoshopped image, Original here:
> Private Supermarine Seafire XVII photo by Stephen Fox


Ah, that makes sense. As it has the older, pre Mk.21, style wings as well


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## fubar57 (Sep 11, 2020)

Photoshop probably made here...Supermarine Spitfire F-Mk.24 by sergueiKAL2020 on DeviantArt


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## GregP (Sep 11, 2020)

Good eyes, Clayton and Fubar. Actually, I just found a quick pic of a Spit 24 and didn't examine it very carefully. I was looking at overall lines.

Even a quick pic can be a "gottcha." Makes you want to somehow be able to cause automatic delete for "fake news," and "fake pics," doesn't it?

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## rochie (Sep 11, 2020)

Why would anyone photoshop that ?


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## GregP (Sep 11, 2020)

Good question, rochie. It's like photoshopping a pic of your own girlfriend, one you still like. What's the point?

Anyone who knows Spitfires will recognize the fake and, if they don't, exactly what is the point of it?


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## SaparotRob (Sep 11, 2020)

GregP said:


> Good question, rochie. It's like photoshopping a pic of your own girlfriend, one you still like. What's the point?
> 
> Anyone who knows Spitfires will recognize the fake and, if they don't, exactly what is the point of it?


Possibly just modeling a plane he’d like to see? Like a Lancaster with jet engines? A “slip-wing Spitfire”? Not everyone can build museum quality models.

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