Bf-109 vs P-40

[Dan Fahey]

One of the key attributes of a good fighter was Range and useful flight time! Here is where I think the Spitfire was over rated. Great performance but could not stay in the fight. That attribute was characteristic of every US plane other than the P39. All had decent to great range which made them successful because could fight in the enemy's neighborhood. All of the US planes were multifunctional as they were used as Recon, Fighter, bomber, fighter and liaison. Spitfire and Me109 carried limited fuel and ordinance to fight. The P40 was an attack plane. What is not written is that when it got toward the enemy base they had burned off more than half of their fuel. The Germans planes were fueled to the limit. As the Me109 and Italian planes had a 90 minute fuel supply, same for the Spitfire and P39. Meaning the P40 was quite a bit lighter for dogfighting! The P40 as a FB could drop ordinance and able to fight its way back home. Examining what Allied losses were many P40 were shot down laden with bombs. However this made the P40 twice a dangerous as the German and Italian Fighters. Where they beat them on the ground and air using the same plane. Where the Germans needed two or more types of planes to perform the same functions.

Here is my point, if the P40 burned off 150 gallons of fuel. It was 1000lbs lighter improving its nimbleness. This same thing played out for the next generation fighter the P51. Here no other aircraft caught up to the Mustangs muiltirole versatility and able to do them as well to far better than any other AC during WW2. That includes the new Jets. A mear 5 years later it would be a different story. Then again in Korea no other USAF plane was available for CAS.

Despite all the clamor the P47 would have done better. No...it was to way too heavy and slow on takeoff to be used on the short Japanese built airfields in South Korea. Plus would have taken twice the fuel load the Mustang would use for missions! It's large oil tank when hit would flame up like Corsairs. Especially the first year. But that is another story away from discussing the P40.

Another reason the P40 was useful because its flight mechanisms were well sorted out from its beginnings as a P36. The P38 was a nightmare in comparison. Tuning the Turbo Supercharged engines lacked well trained mechanics. Taking 3 years to sort out the flight problems, bugs and nuances to make it a consistent effective fighting machine. Still after all the sorting the Mustang was still the dominant US fighter.

In the Pacific the Late model P40 had much better altitude performance against the Zero. Late model Zeros were heavier and less nimble though more capable with better guns and armor with a decent diving speed. Making them a fair match. Interesting watching YouTube where former Japanese aces described the Zero as an acrobatic plane and not a proper fighter. They very aware of its weaknesses and very brave pilots to fly those timber boxes. They further commented that the N1K2 as the first Japanese Navy to be on equal or better terms than the Americans.

 

[ptraney]

No facts here...I just must say the Bf-109E is one of my favorite airplanes. The majority of my collection had one example of every plane or jet that I like. Exception...Bf-109E and P-51.

 

[J.A.W.]

My take on how well the 4 major pre-war fighters fared in wartime development - goes..
from least to most effective:

4, Hurricane, sturdy workhorse & shouldered the burden of British RAF overseas fighter duties for most
of the 1st 1/2 of the war, received the benefit of R-R's splendid Merlin development (before the Spitfire)
so it could tote 4 X 20mm Hispanos.. but it was well past its best-by-date in `43, & being kept in mass
production through 1/2 of `44 was an indictment on British politico-industrial management..

3, P-40, I have little to add to what the well considered posts here already show, but to the credit of US
procurement policies, it was duly cut from the mix even - if C-W had no replacement of their own, when
the masses of Merlin Mustangs coming on stream in late `43 - made the venerable Curtiss look old.

2, Bf 109, although also somewhat limited by its mid-30s origins, by ~10 years later, & not having had
as many 'do overs' as the Spitfire, - in its interceptor niche, & when properly flown, the latest G/K types
could still offer a performance margin ( in the vertical) over Merlin Spits, & go head-to-head with
P-51s & the (fairly rare) Griffon Spits, as well as the latest Soviet jobs, which is something the P-40
could not do by `44/45.


1, Spitfire, the very epitome of a 'grandads axe', the Spitfire is a marvel of the British fetish for
'development' & even if most of the effective combat Spits were 'interim lash-ups' while few
of the dedicated upgrade Mks showed up for service in wartime, I'll have to - just - give the Spit
No1 spot here, based on both the 'hot-rod' performance of the Mk XIV, the finesse of the final
well-sorted Mk VIII, & the - although really too late for the war - Mk 22/24 - due to the fact that they were still more useful than their intended, 'height of tech' successor, the Spiteful...

 

[Schweik]

This is what RAF BoB veteran, Spitfire ace & hugely experienced ( 550+ op sorties) combat fighter pilot
Bob Spurdle had to say about the P-40...

They had the flying characteristics of a brick."

Ol' Bob was a straight-shooting Kiwi, & used his P-40 well, to destroy a couple of Zeros over the Soloman Is,

Yeah that is fine, but multiple other aces and hugely experienced, no-nonsense fighter pilots- Aussies Clive Caldwell (28 victories, 22 flying P-40s) and Nicky Barr (12 victories, all on the P-40), Brit Billy Drake (24 victories, 13 in the P-40), American Robert DeHaven (14 victories), a bunch of Soviet aces and pretty much the entire AVG and 23rd Fighter Group, all praised the P-40 and pointed out that it could easily outmaneuver the Bf 109 within it's altitude ceiling.

As for the New Zealanders - they generally loved the P-40 and had one of the best records with it -99 claimed victories for 20 losses.

"At over 20,000ft, a B-24, having dropped its bombs, could climb away from a Kittyhawk...
& this is exactly what happened."

The P-40 had an altitude ceiling of about ~16k' (Allison engined versions) or 20k' (Merlin engined versions) - it certainly performed poorly above that altitude.

S

 

[J.A.W.]

Yeah that is fine, but multiple other aces and hugely experienced, no-nonsense fighter pilots- Aussies Clive Caldwell (28 victories, 22 flying P-40s)...
The P-40 had an altitude ceiling of about ~16k' (Allison engined versions) or 20k' (Merlin engined versions) - it certainly performed poorly above that altitude.

I guess that after experiencing the climbing capabilty of a Spit IX, ol' Bob naturally found the
P-40 a tad pedestrian,
& he laughed at his fellow countrymen who enthused at what a 'hot-ship' it was, so I'm
guessing those other guys
hadn't..

Albeit, Bob commanded 80 Sqd RAF when they transitioned from Spits to Tempests,
& regarded the Spit IX as 'dainty', & 'feminine' - thereafter, what with the Tempest being much more - 'warlike' - n'all..

 

[Schweik]

I guess that after experiencing the climbing capabilty of a Spit IX, ol' Bob naturally found the
P-40 a tad pedestrian,
& he laughed at his fellow countrymen who enthused at what a 'hot-ship' it was, so I'm
guessing those other guys
hadn't..

Yeah I certainly can understand why coming from a Spit IX to a P-40 of any model would be a let down. If i had a choice for combat I'd go with a Spit IX for sure. Spit V would be more of a toss up, would depend on the subtypes.

Albeit, Bob commanded 80 Sqd RAF when they transitioned from Spits to Tempests,
& regarded the Spit IX as 'dainty', & 'feminine' - thereafter, what with the Tempest being much more - 'warlike' - n'all..

This seems to have been one of the criticisms the Russians had for the Spit, a rep (deserved or otherwise) for fragility. That may have had more to do with the narrow gauge landing gear than anything else though.

S

 

[Schweik]

Here is my point, if the P40 burned off 150 gallons of fuel. It was 1000lbs lighter improving its nimbleness. This same thing played out for the next generation fighter the P51. Here no other aircraft caught up to the Mustangs muiltirole versatility and able to do them as well to far better than any other AC during WW2. That includes the new Jets. A mear 5 years later it would be a different story. Then again in Korea no other USAF plane was available for CAS.

This is a very good point. When P-40s are compared to axis fighters it's almost always on the basis of fully loaded weight, i.e. sufficient fuel for a 700 mile trip not counting the drop tank, whereas on an escort or strafing mission - after takeoff, climbing to altitude, forming up with the bombers and flying to the target (often an enemy airfield) they routinely meet the enemy with two thirds or half fuel.

So lets look at the wing loading of a P-40F for example goes from 35.2 -not bad, much better than a Bf 109G2 38-41 llbs / sq ft), better than a Bf 109F4 (36.76 lbs / sq ft) slightly better than a fully loaded MC 202 (at 35.7) and way better than a Fw 190 at 45 lbs/sq'.

But if they used up half the fuel, the P-40Fs wing loading drops down to 31.8 - a big difference. If you add to that removal of a couple of wing guns and their ammo (standard on the P-40L), that's 29.6 a substantial advantage. Still not quite as good as a Spit V at 25, but comparable to a Spit IX LF at 31.(Source for wing loadings, the wiki only gives wing loading for the G-6 so I went for what i could find). Of course the German planes would get lighter after a long flight too but it's less effect since they carried less fuel.

At half fuel horsepower to weight ratio on a P-40F similarly jumps from ~15 hp/lb to 18.5 hp/lb

When they were used for interceptions / scrambles, P-40s were often only loaded with half fuel or even less. This is documented going all the way back to Java.

Despite all the clamor the P47 would have done better. No...it was to way too heavy and slow on takeoff to be used on the short Japanese built airfields in South Korea. Plus would have taken twice the fuel load the Mustang would use for missions! It's large oil tank when hit would flame up like Corsairs. Especially the first year. But that is another story away from discussing the P40.

P47s were fantastic high altitude fighters with fire breathing beasts for engines and brutal firepower, but I kind of wonder how great their maneuverability was down low. The irony that they ended up being used so much for ground attack is that they may have been fairly ill-suited for it in some respects (size as a target, low speed agility and low altitude maneuverability)

Another reason the P40 was useful because its flight mechanisms were well sorted out from its beginnings as a P36. The P38 was a nightmare in comparison. Taking 3 years to sort out the flight problems, bugs and nuances to make it a consistent effective fighting machine. Still after all the sorting the Mustang was still the dominant US fighter.

Agreed but the Mustang- the Merlin engined one, wasn't around until arguably after the tipping point of the war. The Allison engined one seemed to be mainly used for dive bombing and recon. The P-38s were a factor in the Med in 1943 but they were taking a lot of losses, more than the US P-40 units were. On the Allied side, I would argue that the only truly great fighter which made it into the breach in time (in its truly great form) on the Allied side in the key years of 1942 and 1943 were the Spitfire, specifically the Mk IX, and arguably the Corsair. The Spit V, the Yak-9 and La 5, the P-47 and P-38, the Wildcat and Hellcat and yes the P-40 were all able to do some damage to the enemy. The Corsair still had some bugs to work out in 1943 but it was clearly already a fantastic plane. The P-38 didn't really mature until 1944 and even then, not ideal for ETO / MTO. The Mustang and the Yak-3 and La-7 would become the other three great allied prop fighters of the war IMO.

In the Pacific the Late model P40 had much better altitude performance against the Zero. Late model Zeros were heavier and less nimble though more capable with better guns and armor with a decent diving speed. Making them a fair match. Interesting watching YouTube where former Japanese aces described the Zero as an acrobatic plane and not a proper fighter. They very aware of its weaknesses and very brave pilots to fly those timber boxes. They further commented that the N1K2 as the first Japanese Navy to be on equal or better terms than the Americans.

That's very interesting, links? i always wondered how much of a performance hit the addition of armor and self-sealing tanks had on the A6M.

S

 

[Dan Fahey]

Regarding the Zero...read Complete Book of WW2 Combat Aircraft - Military Press - Enzo Angelico and Paola Matricardi.
The Zero got more Armor, stronger wings, more fuel capacity, second stage blower.
They copied the Browning 50 cal and built a better 20mm upscaling the machine gun.
Late models got 13mm machine guns in the nose.
Weighing more it needed the 1500 hp engine the Ki100 got.

The late model P40 got the -81 to -117. The last 220 P40 built had a 1350 hp Allison.
Basically standardizing on the field mods to make more power and late model P40s got a bit lighter.
Wonder if mechanics used the PEP 44-1 150 octane fuel in the field?
Properly tuned 1800 HP. The Turbocharged P38 was tested to 2000hp.

One other thing.
The Allison Engine was a much better more rugged, powerful and reliable engine than the Merlin.
The Merlin had twice the number of parts to assemble it. Called the Watchmakers Engine.
Packhard fixed a bunch of issues, such as adding far better bearings.

The Merlin's success came from a very well designed 2 stage 2 speed supercharger.
The Allison was limited not having a compact 2 Stage 2 speed supercharger.
Their singe stage were much better than the Merlin's.

Had Allison collaborated with British engineers it would have been a premier high altitude engine.
The F82 with the Allison had constant back fire issues.
Allison turned down British (Merlin Enginners) help to solve it.
Allison did some work arounds but the F82 engines were cranky.
When they ran good they were right there but still down on power compared to the Merlin's.
Like other Allison they performed brilliantly 20k and under.

It is interesting how the Americans built good planes but limited HP.
The British desperate to survive hotrodded the P51A Allison engine.
US flew them for 100 octane. The British their 130 octane fuel.
This was that same fuel that drove P38 pilots and mechanics nuts.
All because of incorrect tuning and ignorance by Lockheed and Allison to make them more combat read.

Wonder if there was an test data recorded on the P51A using the British 130 fuel.
Certainly none with the US150 octane in the Allison.

Again here is another area overlooked regarding the P40.
It could fly combat missions in any kind of weather.

 

[Schweik]

Regarding the Zero...read Complete Book of WW2 Combat Aircraft - Military Press - Enzo Angelico and Paola Matricardi.

I was referring specifically to the interviews with Japanese pilots you were talking about as well as any data on degraded performance of the later model A6Ms. I have 40 or 50 books on fighters and 2 or 3 specifically on the Zero though most of them repeat the same stuff.

The late model P40 got the -81 to -117. The last 220 P40 built had a 1350 hp Allison.

Actually all of the 1300 P-40K fighters some (I think ~200) of the later run P-40E had V-1710-73 rated officially at 1325 hp. The only real innovations on the V-1710-73 was automatic boost control and a stronger crankshaft which could handle the overboosting they were doing with the earlier models. 57" of boost became the standard WEP setting. From what I gather that could actually mean ~1500 hp at certain altitudes.

~ 300 of the P-40Ns (some of the early models as well as some of the later ones) had the 1350 or 1360 hp -1710-99 and -117

I think the -81 was a lower rated 1200 hp version used on the export / fighter-bomber variants of the P-40N and M

Allison had a lot of problems, similar to though not as bad as Curtiss. they had been purchased by GM in the early 30's and were kind of bogged down in corporate bureaucracy and spent more efforts on influence and what we today call lobbying than on innovation.

Some of the pilots interviewed in Christopher Shores Mediterranean Air War mentioned they liked the P-40K better at lower altitude, but the Merlin XX / V-1650 engined P-40F and L performed better at altitude and had an effective performance ceiling of 20,000 feet. As a result they flew the escorts missions for bombers and fighter bombers (including other P-40s) most of the time.

S

 

[Stig1207]

P-47's began replacing P-40's in the autumn of '43 in the MTO; by August '44, there was not a single P-40 with white stars in the theatre.
P-38's escorted 15th AAF bombers over Germany right up to the end of the war.

 

[Juha2]

One of the key attributes of a good fighter was Range and useful flight time! Here is where I think the Spitfire was over rated. Great performance but could not stay in the fight. That attribute was characteristic of every US plane other than the P39. All had decent to great range which made them successful because could fight in the enemy's neighborhood. All of the US planes were multifunctional as they were used as Recon, Fighter, bomber, fighter and liaison. Spitfire and Me109 carried limited fuel and ordinance to fight...

Generally true, but there were many different versions. Without touching the Spits with rear fuselage fuel tanks, Mk VIIs and VIIIs carried 121½ - 124 ImpGal fuel and had reasonable range but only the 140 high altitude Mk VIIs stayed in ETO, all Mk VIIIs were sent to MTO, CBI and Australia. And LR PR Spits could reach beyond Berlin from UK, even USAAF 8th AF used some PR Mk XIs. And Mk IX could carry 1000 lb of bombs as a FB, so they had some ordanance carrying capacity, even if not like e.g. Typhoon.

 

[Juha2]

Hello a small note to Schweik's message, #609, already La-5FN was very capable plane, it had the same engine than La-7 but because the engine had better cooling in La-5FN, the engine in -5FN was clearly more reliable than in -7, even if it was somewhat draggier and so slower.

 

[Greg Boeser]

Just like the late model P-40s escorting the earlier models, US FGs equipped with Spitfires would fly top cover for Mk Vs with Mk IXs.

 

[Schweik]

Hello a small note to Schweik's message, #609, already La-5FN was very capable plane, it had the same engine than La-7 but because the engine had better cooling in La-5FN, the engine in -5FN was clearly more reliable than in -7, even if it was somewhat draggier and so slower.

Yeah I didn't include La 5FN in the "greats" list because I just thought La 7 was kind of the definitive version of it. when did La 5FN become widely operational and relatively 'bug free"? I know some kind of La 5 were available in late 1942 or early 1943 right?

S

 

[tomo pauk]

Actually all of the 1300 P-40K fighters some (I think ~200) of the later run P-40E had V-1710-73 rated officially at 1325 hp. The only real innovations on the V-1710-73 was automatic boost control and a stronger crankshaft which could handle the overboosting they were doing with the earlier models. 57" of boost became the standard WEP setting. From what I gather that could actually mean ~1500 hp at certain altitudes.

~ 300 of the P-40Ns (some of the early models as well as some of the later ones) had the 1350 or 1360 hp -1710-99 and -117

I think the -81 was a lower rated 1200 hp version used on the export / fighter-bomber variants of the P-40N and M

The -81 was outfitted 9.60:1 drive for supercharger. Result of that was improvement of altitude performance by some 10% above 14000 ft, the trade off being a loss of low-altitude performance by about same percentage. 1200 and 1325 HP power figures are for take off, that is a nice-to-have thing for a fighter, however the altitude power is more important, hence the engines similar to the -81 being better for the P-40s/39s/51s.
The real innovation for the -73 was strenghtening of some parts (crankshaft, or was it the crankcase?), allowing for greater boost and thus the power under 5000 ft (including take off power that was 1150 HP in previous types, like the -39). Both -39, -73 and similar engines were outfitted with 8.80:1 drive for supercharger.

 

[Schweik]

P-47's began replacing P-40's in the autumn of '43 in the MTO; by August '44, there was not a single P-40 with white stars in the theatre.
P-38's escorted 15th AAF bombers over Germany right up to the end of the war.

All true - and I would also add that the USAAF planned to replace P-40s as far back as 1941. P-40s, as an adaptation of the competent but basically obsolescent P-36 was seen as a kind of stop-gap fighter. The original hope was that the more "futuristic" P-39 would replace it. This is why P-39s were for example put into service in Guadalcanal. But combat experience quickly showed that the P-40 was a lot better, and had a chance against the A6M whereas the P-39 was basically dead meat (or an "iron dog" as the pilots there called it).

Then the plan was to replace the P-40 with the P-38 ASAP.

In the Pacific, this was done, but much more gradually than planned, the main reason being the various development problems with the P-38 and a relatively slow rate of production. In spite of all the issues with the plane though, some pilots figured out how to do a boom and zoom attack vs. Japanese planes utilizing a high-speed climb.

In the CBI, it was found the 23rd Fighter Group was able to continue using AVG tactics and build upon them, and P-40s remained in use until the end of the war, though gradually replaced by P-51s. Some pilots in the CBI noted that they actually preferred the P-40.

In the Med and Italy, it was hoped to replace P-40s with P-38s as early as 1942, but early P-38s proved to be of questionable merit against Bf 109s and while I'm still not certain of this, from Shores it appears that the P-38 units took heavier losses than the P-40 units. Anyway there were definitely more P-40 Aces in the Med.

In Italy they did start replacing P-40s with P-47s, and I think the main reason is the high altitude performance, for interception and especially for escorting B-24s and so forth, even though they were more often used for fighter bomber missions for which they were not ideally suited. Not all pilots (for example in the 79th FG) preferred the P-47 incidentally and P-47s were in turn replaced in many of those same units (325 FG etc.) by P-51s as soon as they were available. The RAF still used P-40s right to the end of the war in Italy, also mostly for fighter-bomber missions.

In Russia they used P-40s on the front line through 1943, after which they were relegated mainly to PVO (combat air patrol) units where they remained in use until 1945 (but then again so was the Spit IX). Their main problems with the P-40 had to do with maintenance issues.

The US War Department had plenty of reasons to dislike the P-40, the altitude performance issue being the main one, but also numerous chronic problems with Curtiss Aircraft and Allison being another. But they kept using them anyway.

The TL : DR is that while P-40s were supposed to be gone or phased out by mid-1942, they were still being heavily used in combat well into 1944, and were phased out only in 1945. The reason? P-40s were still able to shoot down enemy fighters and survive fighter-bombing missions as well or better than other available types - Hurricane and P-39 for example had comparatively dismal records in the Med and Pacific / CBI. The replacements came as soon as they were available.

Frankly based on performance I think the P-40 should have been phased out by the end of 1943 unless they could put a Merlin 60-series engine in it. But they had the P-51 by then.

S

 

[Schweik]

Generally true, but there were many different versions. Without touching the Spits with rear fuselage fuel tanks, Mk VIIs and VIIIs carried 121½ - 124 ImpGal fuel and had reasonable range but only the 140 high altitude Mk VIIs stayed in ETO, all Mk VIIIs were sent to MTO, CBI and Australia. And LR PR Spits could reach beyond Berlin from UK, even USAAF 8th AF used some PR Mk XIs. And Mk IX could carry 1000 lb of bombs as a FB, so they had some ordanance carrying capacity, even if not like e.g. Typhoon.

Maybe you can answer a question for me on this - I had read that the Spit VIII etc. was a "long range" version of the Spit, but in googling it recently i saw range figures of ~650 miles which sounds like 'medium' range at best. A little less than most US fighters except the Wildcat. Is that the right number? What is the actual range of the Spit VIII?

S

 

[Schweik]

The -81 was outfitted 9.60:1 drive for supercharger. Result of that was improvement of altitude performance by some 10% above 14000 ft, the trade off being a loss of low-altitude performance by about same percentage. 1200 and 1325 HP power figures are for take off, that is a nice-to-have thing for a fighter, however the altitude power is more important, hence the engines similar to the -81 being better for the P-40s/39s/51s.
The real innovation for the -73 was strenghtening of some parts (crankshaft, or was it the crankcase?), allowing for greater boost and thus the power under 5000 ft (including take off power that was 1150 HP in previous types, like the -39). Both -39, -73 and similar engines were outfitted with 8.80:1 drive for supercharger.

It was the crank shaft, they first improved it using 'peened' metal in early 1942 then used heat treated metal. I think some other components were strengthened a bit. 57" mercury became the standard WEP setting on the P-40K and apparently they could use it for a long time. Prior to that the official WEP rating was 45, though 57" was common and there were Overboosting claims of up to 70" by pilots (and a rather famous or infamous letter from Allison advising against it)

Why does this only confer extra HP up to 5,000 feet?

Interestingly they also overboosted the Packard Merlin 1650s to 60" apparently.

I never quite understood the 8:80:1 vs. 9.60:1 gearing issue. Can you elaborate on that a bit?

S

 

[Shortround6]

I never quite understood the 8:80:1 vs. 9.60:1 gearing issue. Can you elaborate on that a bit?

at 3000rpm the supercharge impeller was spinning at 26,400rpm with 8.80 gears and with 9.60 gears you get 28,800.
Power needed to drive the supercharger goes up with the square of the speed of the impeller which is where the early failure of the 9.60 gears comes from.
about a 17% increase in power needed.

 

[Schweik]

at 3000rpm the supercharge impeller was spinning at 26,400rpm with 8.80 gears and with 9.60 gears you get 28,800.
Power needed to drive the supercharger goes up with the square of the speed of the impeller which is where the early failure of the 9.60 gears comes from.
about a 17% increase in power needed.

So how does that translate into HP at different altitudes?

I wonder if we should update the wikipedia page on the various V-1710 variants could be helpful to a lot of people.