Bf-109 vs P-40

Schweik said:

According to my records, the V-1650 / Merin 28 on the P-40F/L got up to ~1450 hp at max boost, whereas (by mid 1942) the P-40E was rated at 1470 hp at the 'official' WEP setting of 56" and the P-40K was rated at 1550 hp at it's official WEP setting of 60" Hg. Both engines were reportedly sometimes operated at overboost as high as 66" or even 70-72" Hg for over 1,700 hp.



65" is overboost for that engine, by a considerable margin. And it's obvious he was using it a lot longer than 5 minutes. It means he was probably operating at ~1,500 hp or more.

I believe the 61" rating had actually developed from combat experience, increased from a previous lower rating. Much like the "official" WEP rating had gone from 45" to 57" for the Allisons and in the field 60" (secretly acknowledged by Allison) and routinely 65" - 72" by actual combat units, for up to 20 minutes according to that report on the Mustang I.

In this case it appears Lt Mobbs was running his P-40F on 65" boost for more than 20 minutes. Enough Hp for long enough to outrun a Bf109F-4.

S

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If they were over boosting. That would,mean they were using the British 100/130 octane fuel. Not the US 100 octane fuel.
Can someone verify this?

D

Dan Fahey said:

If they were over boosting. That would,mean they were using the British 100/130 octane fuel. Not the US 100 octane fuel.
Can someone verify this?

D

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They didn't need 130 octane fuel to overboost - it just made it safer to overboost more. I think it had to do with spark plugs fouling among other things.

I believe the Americans also had high octane fuel, I think up to 150. Shortround do you know?

S

wuzak said:

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

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Yes been posted many times. There is also this memo which discusses overboosting on British (Allison Engined) mustang Is - up to 72" for 20 minutes with no

E-GEH-16

The US used the British fuel in WW II as far as I know. It was only used in Europe. The Americans were working on a 115/145 fuel which became standard post war but I don't believe any was used during WW II. The Americans wanted the higher lean number to improve cruise performance.

The 100/150 fuel (and perhaps the 115/145) was more likely to foul spark plugs even if the extra boost was not used during a flight.
There was no extra power unless the extra boost was used.

There were two kinds of detonation. One was sort of a warning and gave symptoms a bit like a car engine climbing a hill, a rattle or pinging/banging noise coming from the engine. This could lead to piston or piston ring problems with pitting of the piston top or in extreme cases melting a hole in the piston top.
This was the result of fuel igniting due to compression (or hot spots) in places away from the spark plugs and the flame front/s from the different sources of ignition meeting and squeezing the remaining mixture between them and causing it to ignite in a more violent manner.
If bad enough you could get the entire contents of cylinder flashing at once (detonating) rather than 2 or more competing fame fronts moving across the cylinder/piston top. When this happened things could get catastrophic pretty quick. It sometimes happened before the piston hit top dead center so the explosion was trying to turn the crankshaft backwards. This resulted in broken pistons and/or bent/broken connecting rods and crankshaft damage or damage to bearings.
It sometimes tried to lift the cylinder head on V-12 engines (stretching or breaking bolts/studs) and on air cooled engines had been known, on occasion, to blow a cylinder completely off the crankcase.
It took very brave (or desperate ) pilots to really push the detonation limits in flight.

I would note that some pilots who pushed things a bit too far might be listed as lost under "unknown causes". Just because pilot A used 70 inches for 20 minutes on Tuesday morning doesn't mean that pilot B got away with it on Thursday afternoon. Different air temperature, different engine with more hours on it, spark plugs not in the same condition.

Or pilot A used the 70in for 20 minutes on Tuesday and the plane flew on Thursday and Friday and then the engine lost a bearing or threw a rod on Saturday on take-off.
Can the squadron engineering officer trace Saturday's failure back to Tuesday?

Yeah I hear all that, but this is pretty clear to me:

"The British have operated at full throttle at sea level (72" Hg) for as much as 20 min. at a time without hurting the engines. According to them, the Allison is averaging 1500 hours between bearing failures as compared to 500 to 600 hours for the Merlin. The Allison, they have found, will drag them home even with the bearing ruined. "

This guy was recommending a policy change specifically for units in North Africa. I don't think he would have been that definitive if he had any reason to believe they were getting engine failures after running hard (though no doubt, 20 minutes at 72" would shorten the time to the next overhaul).

I also read your comments on how hours between failures may be calculated and how bearing failure wasn't the same as engine failure. However a couple of facts come to mind:

• We know they were overboosting at similar rates in the Med as well, and
• We know that an engine failure even at low altitude did not automatically mean pilot death in fact
• Hundreds of DAF pilots in fact did survive crash-landing their fighters at low altitude and live to tell the tale
• ...and we know the P-40s in general and Allison engined ones in particular did not have a reputation for mysterious engine failure, to the contrary.
• Most engine failures were due to combat damage and quite often they made it home in spite of bullet holes, even damaged radiators. I read 3 anecdotes so far of pilots landing to let the radiator cool down and taking off again, and two of a guy actually reparing his engine somehow and taking off again to make it back to base.

So while I concede that it's possible a plane flying back over the channel at 50' had a sudden engine failure and just died mysteriously, to be listed as FTR or whatever, but I can tell you they didn't have that mysterious, unknown losses of P-40s in the Med. It's maybe 2 or 3% of their losses. They were usually aware of the cause and they certainly tracked the causes as much as they could.

I'm confident that General Born knew what he was talking about in that memo when he suggested they increase the default boost settings on the throttles, and I'm confident they would know if they were actually getting high losses as the result of overboosting.

S

You also have cross timing, The memo is dated August of 1943. They had stopped production of Allison P-51s in May, 3-4 months earlier.
The Americans had a grand total of 55 F-6A photo planes (P-51s) with -39 engines (the ones the British were over boosting in Europe) with 8.80 supercharger gears.
They had 500 A-36s with the 7.48 supercharger gears and there was no way those engines would every reach 70in of manifold pressure without running the engines well beyond 3000rpm. (which is another can of worms)
ANd then the US had 260 P-51As with 9.60 supercharger gears (V-1710-81 engines) and these were the ones that the Allison reps were really worried about as the higher gear ratio heated the intake air more and pushed the engine closer to the detonation limits. which is why Allison only rated them at 57 in WEP power.

I really have no idea what planes he was suggesting that the boost limits be raised on.
The F-6As which were about the only planes/engines that would actually hit those limits were used by two squadrons in North Africa/Italy. The 154th observation squadron and the 111th Photo Recon squadron.
It didn't matter what the British were doing with their -39 engines in hundreds of Mustang Is if your Mustang/Apaches in North Africa/Italy have different engines with different supercharger gears.

Shortround6 said:

I really have no idea what planes he was suggesting that the boost limits be raised on.
The F-6As which were about the only planes/engines that would actually hit those limits were used by two squadrons in North Africa/Italy. The 154th observation squadron and the 111th Photo Recon squadron.
It didn't matter what the British were doing with their -39 engines in hundreds of Mustang Is if your Mustang/Apaches in North Africa/Italy have different engines with different supercharger gears.

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Well, in 1943 the DAF still had a couple of thousand Kittyhawk I and Ia (P-40 D and E) fighters which used the same V-1710-39 in that Mustang, and several hundred Kittyhawk III (P-40K*) fighters both in RAF / Commonwealth use and in some of the American Fighter Groups, which used the V-1710-73 -which as you know is a reinforced, tougher (and therefore higher rated) equivalent of the -33. Both of which engine types had the low 8.8 gear ratio and could be (and we know, were) overboosted to very high manifold pressure settings.

Also while I'm sure the higher geared -81 and -110 etc. Allisons were a bit riskier to boost all the way up to 72", it's clear that they did overboost them as well. The Allison memo recommends using the higher grade fuel. They didn't say anything about reducing overboost below their already agreed to level of of 60".

The 1943 Mustang memo is mainly relevant in that it confirms and reinforces the 1942 Allison memo. If they could boost Mustang I to 72" with V-1710-39 for 20 minutes with no engine damage, I don't see any reason why they couldn't do the same with P-40Es flying with the same engine, except possibly for Desert conditions.

By the way the Soviets did mention specifically running Kittyhawk engines at higher RPMs to increase power. When I first read that I thought it was a mistranslation of increased manifold pressure, but it may have meant running higher RPM to increase boost potential.

S

*RAF Kittyhawk III category also included P-40M which had the higher 9.6 gear ratio.

Allison engine overboost in late 1942 US mock combat trials:

9. ZERO vs P-3D-1:

Climb from sea level to five-thousand (5000) feet
indicated. Take-off was accomplished in formation on signal.
P-39D-1 was drawing 3000 RPM ard seventy (70) inches manifold
pressure. Engine started to detonate so manifold pressure was
reduced to fifty-two (52) inches. P-39D-1 left the ground first
and arrived at five-thousand (5,000) feet indicated just as Zero
was passing four-thousand (4,000) feet indicated, Fifty-two (52)
inches manifold pressure could be maintained to four-thousand
five-hundred (4,500) feet indicated. At five-thousand (5,000)
feet indicated from a cruising speed of two-hundred-thirty (230)
miles per hour indicated the P-39D-1 had a marked acceleration away
from Zero. Climb from five-thousand (5,000) feet to ten-thousand
(10,000) feet at the respective best climbing speeds, (thus elimi-
nating zoom) P-39D-1 reached ten-thousand (10,000) feet indicated
approximately six (6) seconds before Zero. At ten-thousand (10,000)
feet indicated, from a cruising speed of two-hundred-twenty (220)
miles per hour indicated, P-39D-1 still accelerated away from
Zero rapidly. Climbing from ten-thousand (10,000) feet to fifteen-
thousand (15,000) feet, both airplanes maintained equal rates of
climb to twelve-thousand five-hundred (12,500) feet. Above this
altitute the Zero walked away from the P-39D-l. At fifteen-
thousand (15,000) feet indicated, from a crulsing speed of, two-
hundred-ten (210) miles per hour indicated, P-39D-l accelerated
away from Zero slowly...
http://www.wwiiaircraftperformance.org/japan/intelsum85-dec42.pdf

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We can see above that it wasn't possible to use 70in boost under the conditions of the test. The low altitude to which 52in boost could be maintain is also noted.

I think the whole idea of the P-40s using 70in of manifold pressure is a bit (or more than bit) overdone, in regards to P-40s having much higher than book performance and being able to outperform German aircraft.
I have no doubt it was done although with a number of the planes not having pressure gauges that read that high some accounts may be a little suspect. (pilot estimated base on far the needle swung back around past zero?)

Mechanical or perhaps physically we have a bit of a problem. The engines with the 8.80 gears were only capable of making 66in of pressure in the manifold sitting on the ground at sea level on a "standard" day. (15 degrees C). the extra 4in of pressure had to come from forward speed or over revving the engine (or both).

Please note that in often posted Allison memo of 12-12-42 that on page two it says that 1780hp can be achieved with 70inches on a 75 Degree F day but only by running the engine at 3200rpm.

This rather amazing amount of power disappears rather rapidly in fight. Without over revving the the engine it depends on Ram (and staying very, very low)
The Ram is from the forward speed of the aircraft and should the aircraft slowdown (hard G turn or climb) the airspeed falls off and the RAM declines.
As an example (poor as it is a different engine and different intake) a Spitfire V with Merlin 45 engine lost 1.7in of MAP dropping from 369mph to 195mph at 13,000ft.

This in itself isn't too bad but the Allison was straining to hit that 66in number to begin with. If the plane is at 3000ft the fall from 29.92 in (round to 30) of outside pressure to 26.81in means without Ram the 66in the manifold has dropped to 58.98.

I think we can see that even with RAM a P-40 or Allison Mustang is NOT going to be climbing using 70in of MAP for very long. At 2000ft the numbers are 27.82in for ambient air and 61.2in for manifold pressure without RAM. This is pretty much why Allison rated the -39 engine at 1480hp at 4300ft at 56in of MAP. At 3000 rom on a standard day the supercharger was maxed out and simply will not supply any more air without the assistance of RAM, there is NO 70in at 4300ft, there is NO 66in at 4300ft, you are lucky to get 60in at 4300ft without over revving the engine by several hundred RPM.
as for power between the 4300ft mark and the rated 11,700ft point? you are going to loose about 1.67in of MAP for every 1000ft you climb until you get to the 11,700ft mark and the 44.6in of MAP, not a whole lot of extra power at 10,000ft.

Please note there will be a slight difference between a Mustang and a P-40 because the higher speed of the Mustang will create higher pressure in the intake duct before the Carb/supercharger (RAM)

I don't know how often they used 70 or 72" but it's clear that they did, the Allison and Mustang memos both spell it out quite unambiguously.

It's also clear you have a hard time getting your head around it but I am definitely not phased by that. You have a lot of knowledge about engines but you don't know everything and frequently disagree with period sources that don't agree with your calculations or theories. It's far more likely to me that you simply haven't considered all the variables.

I have no way of knowing what precise rates of overboosting were most common. I might find out more if I continue to aggregate pilot testimony for a while, but that is limited - and sadly few WW2 pilots are still around. No doubt full 70" was only useful on the deck, but there are so many sources on overboosting now, including with the 9.6 ratio engines, that it's quite clear it was not only a widespread practice, by some point which may have varied Theater to Theater, it was probably universal.

To date, I have basically no information on overboosting Tomahawk era P-40s (Bs and Cs and their equivalent) so I'll skip those.

But when the P-40E first arrived, the official 'WEP' rating was 45" Hg - or at least that is what some squadrons were being told. It was pressure from the pilots which nudged it, and all the other standard settings (takeoff power, military power etc.) upward. Particularly foreign pilots who had bought the planes and could do whatever they liked with them. Then Americans too. First to 51 then 56 or 57", then (per the Allison memo) to 60". The Allison memo mentioned 66" as standard practice in an unnamed unit in the Med, that may have been the sweet spot for them.

The memo on the P-40N shows overboost / WEP did most definitely play a siginifcant role in climb. It shortened the time to 15 and 20,000 ft but it also nearly doubled the climb rate down low, and that of course would make a big difference dogfighting. Fights between aircraft tend to move downward over time.

This combined with the P-40s good dive acceleration and very high dive speed, as well as good high speed handling and specifically roll rate, translates to a routine escape maneuver (Split S and dive down followed by a roll right and turn right). After the escape maneuver, if followed, apply overboost and outperform the enemy like in the example I cited already.

here is another example by the Australian Ace Bobby Gibbes. He doesn't mention specific throttle settings but it's clear his acceleration was greatly increased in the (V-1710-73 powered) "KItty III"

"Well I was a poor shot. Air to ground I think I was a very good shot. I could group my bullets and make sure they didn't run through. I could hold them on target while I went in and strafed. But air to air I certainly missed an awful lot of aeroplanes I fired at. I think the classic example was one day when I had a Kitty Mark III - I had acquired it illegally, I might say - and I had to give it back to the RAF later - but I had a little bit more horsepower than the rest of the squadron and when three 109s passed overhead or ahead of us, if I had waited to take the squadron with me, which normally I would have done, they would have got away.

But seeing them and knowing I had that bit more power I opened the taps and went after them. I had a look at the three of them and I thought, if I pull a lead on the number one, number three could probably get a deflection shot at me, so I thought, well, I'll get number two first. So I fired at number two. I must have misjudged their speed completely because the one behind, probably fifty yards behind, flicked over and went down smoking like hell. I looked round to see who else had shot at it but I was the only one in the sky. I then decided, well, I'll go after the number one and number two but, of course, they didn't wait for me. The one, incidentally, number three, did go in.

Yes, it was a successful mission. We had a big celebration that night in the squadron and a few of the 'Yanks' came over and they thought the shooting was quite brilliant and I had only fired very few rounds. However, during the night I managed to get quite a few grogs on board and I decided that I'd confess that I hadn't even aimed at that one, I'd aimed at the one ahead of it. And, of course, when I did tell them of course no one believed me, but it was true."

Gibbes also said this about the Kittyhawk Mk I:

"Well it was basically the same aeroplane. We were a little disappointed when we first got the Kitty, we thought it'd be way ahead of the Tomahawk. In actual fact, it was a little bit better. One thing I personally didn't like about it was the Tomahawk had fairly high sides and you'd be sitting behind a thin sheet of metal but you felt safer. The Kittyhawk had perspex coming way down and you felt as if you were sitting up, very vulnerable, because you could see out so much. That was one feature I do remember. However, later when we got our Kittyhawks running properly - were getting better performance - they were a better aeroplane."

That sounds to me a lot like overboosting. And probably rewiring throttles as reported in the Mustang memo.

The manifold pressure gauge spinning around back to 20 actually is something that more than one pilot has mentioned. I don't see why it's so startling. I once had a motorbike that did that.

S

Found this interesting quote in the Osprey book P-40 Warhawk Aces of the MTO, P. 65.

This was from a letter by Lt Richard T Conly of the 315th FS / 324th FG describing an April 29 encounter over Tunisia in which he scored his first confirmed victory:

'When I pulled back up, I had just climbed to about 7000 ft when another '202 jumped me at nine o'clock high. I turned into him, and he started turning to get on my tail. At this point I really swore by a P-40, because I could dogfight and out turn him with ease. He saw I was going to get a shot and headed for the deck, strait down. I never got farther than 100 yards behind him, and he stayed right in my sights. I watched my tracers pound into him all the way. Those good old six "fifties" raked him from the tail up. He hit the deck about 50 ft just offshore and went strait in. I almost got wet in the splash.'

Just a particularly clear anecdote out of many similar which emphasized that the P-40s flown by USAAF units at that time (mostly P-40F/L plus some P-40K) could easily out turn the MC 202 / 205, and I also have numerous similar anecdotes about the Bf 109F and G. Will post a few of those later.

It also seems he had no trouble keeping up with it in a long dive.

S

Schweik said:

Found this interesting quote in the Osprey book P-40 Warhawk Aces of the MTO, P. 65.

This was from a letter by Lt Richard T Conly of the 315th FS / 324th FG describing an April 29 encounter over Tunisia in which he scored his first confirmed victory:

'When I pulled back up, I had just climbed to about 7000 ft when another '202 jumped me at nine o'clock high. I turned into him, and he started turning to get on my tail. At this point I really swore by a P-40, because I could dogfight and out turn him with ease. He saw I was going to get a shot and headed for the deck, strait down. I never got farther than 100 yards behind him, and he stayed right in my sights. I watched my tracers pound into him all the way. Those good old six "fifties" raked him from the tail up. He hit the deck about 50 ft just offshore and went strait in. I almost got wet in the splash.'

Just a particularly clear anecdote out of many similar which emphasized that the P-40s flown by USAAF units at that time (mostly P-40F/L plus some P-40K) could easily out turn the MC 202 / 205, and I also have numerous similar anecdotes about the Bf 109F and G. Will post a few of those later.

It also seems he had no trouble keeping up with it in a long dive.

S

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I must say that the anecdotes you quote seem very much like PR blurb, very emotive and flowery language "At this point I really swore by a P-40, because I could dogfight and out turn him with ease. " Had the pilot been in combat in any other type, did he have any connection to the aviation industry?

Just a note on turning.

During the BoB it was found that less experienced pilots in Spitfires could be out-turned by experienced pilots in Bf 109s. This was found in evaluations of captured 109s by experienced test pilots.

When pilots of equal experience and skill were flying the two aircraft, the Spitfire easily out-turned the Bf 109. All about knowing how far the aircraft could be pushed.

In the BoB, many RAF pilots were novices, while Luftwaffe pilots had some experience behind them.

I do not know whether a 202 could out-turn a P-40, but equally the pilot may have lacked the skill and experience to get the best out of his aircraft.

wuzak said:

Just a note on turning.

During the BoB it was found that less experienced pilots in Spitfires could be out-turned by experienced pilots in Bf 109s. This was found in evaluations of captured 109s by experienced test pilots.

When pilots of equal experience and skill were flying the two aircraft, the Spitfire easily out-turned the Bf 109. All about knowing how far the aircraft could be pushed.

In the BoB, many RAF pilots were novices, while Luftwaffe pilots had some experience behind them.

I do not know whether a 202 could out-turn a P-40, but equally the pilot may have lacked the skill and experience to get the best out of his aircraft.

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If the P40 out turned a Italian Fighter. It was about a 1000 lb lighter because they used a good half of their fuel to travel and attack the Italian bases. The Italian Fighters were filled with fuel to intercept. So weighs would have been similar.

That was one of the features of the P40 it had a decent range. In the combat zone competitive performance. The higher boost levels did not increase speed that much compared to the Mustang. It did improve combat speed range and climb performance.

The P-40 had a slightly lower wing loading at 1/2 fuel than the MC 202 did with full fuel. As in a P-40E with 600lbs of fuel on board (1/2 fuel if the drop tank is counted.) has a wing loading of 91% of the MC 202 sitting in dispersal with tanks full but engine not started.

A P-40E with 1000lbs of fuel gone is in serious trouble over an Italian fighter base. It has 200lbs of fuel left. 33-34 gallons. enough for 1 hour flying low and slow.
enough for 11-12 minutes using the overboost some forum members are so fond of. Not enough to do both.

You start getting into differences in wing loading of close to 5% (P-40K was several hundred pounds heavier than the E, and the MC 202 was going to burn 150lbs or more of fuel starting, warming up and taking off.) and things get too close to call. Can either pilot really fly that close to stall? Is each plane flying the exact same speed? even a difference of 10mph is going to make a small difference in turning circle. We don't know the actual coefficient of lift at the angle/s of attack being used in the tight turns (or the coefficient of drag).

Look at the arguments concerning the Spitfire (wing loading 24lb/sq/ft) and the 109E ( wing loading 32lb/sq/ft) and then try to figure the difference between two planes that were between 32.6lb sq ft and 35.7lbs sq ft depending on fuel state (and I am knocking several hundred pounds off the P-40 internal fuel capacity).

Shortround6 I think this is a good example of not applying your considerable knowledge to the right data and therefore reaching (or reinforcing) an inaccurate conclusion. You are making several assumptions here which are incorrect.

First of all this

Shortround6 said:

The P-40 had a slightly lower wing loading at 1/2 fuel than the MC 202 did with full fuel. As in a P-40E with 600lbs of fuel on board (1/2 fuel if the drop tank is counted.) has a wing loading of 91% of the MC 202 sitting in dispersal with tanks full but engine not started.

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Is based on what?

Your wing loading comparison seems to be off- the P-40E had a better wing loading from the start.

My data:

• MC202 (Serie IV) Loaded Weight of 6,458 lb, wing area 181 ft², wing loading 35.67
• P-40E Loaded Weight of 8,280 lb, wing area of 235.94 ft² wing loading 35.09

P-40 is lower before burning a drop of fuel. By the time they flew to a target it would be considerably lower. For Bf 109s, I have seen wing loadings from 34-36 for Bf 109F-2, from 35-37 for Bf 109F-4, 37-41for Bf 109G-2 and G-4, and 41-44 for G-6. Obviously it depended exactly how they were loaded and you can find different weights for all the planes mentioned, but in the Med, when planning a fighter sweep or escort mission, they actually lightened their planes as much as possible.

A P-40E with 1000lbs of fuel gone is in serious trouble over an Italian fighter base. It has 200lbs of fuel left. 33-34 gallons. enough for 1 hour flying low and slow.
enough for 11-12 minutes using the overboost some forum members are so fond of. Not enough to do both.

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Where is this hypothetical Italian fighter base relative to the hypothetical American base?

DAF pilots in fact did 1) fly over Italian fighter bases (often carrying bombs) perform ground attack, dogfight, in many cases use WEP / overboost, and then fly back to their own base, sometimes fighting all the way. Please see post 690 on this and also, for your convenience, the same passage from Google Books. Note they were overboosting over the enemy base and all the way back.

It sounds like maybe you are thinking of a base several hundred miles away, like in Italy if they were flying from Algeria or Tunisia. In the example I cited the base in question was in Tunisia about 150 miles from the DAF base which was in (North East) Algeria.

Your fuel use calculation seems to be wrong

We have discussed this before, but most of the fuel on the way to a target would be burned from the external tank.

You are assuming the wrong fighter types

You mentioned the P-40E but USAAF pilots flew mostly P-40F and L, (and a few K) by that action which was in April of 1943, it would mostly be P-40L. P-40L was considerably lighter than the E in part because less fuel (also 4 guns instead of 6 and less ammunition).

• P-40L Loaded Weight at 8,020 lb, wing loading of 33.9

Of course, MC 202 weight varies by type and by field mod. On the upper end of the scale, by April 1943 the Regia Aeronautica were using MC 205 and they lost a few of those at that time. MC 205 was much heavier with a wing loading of around 41 lbs / ft². On the other hand, I have read from Italian pilots that said they often removed the .30 cal wing guns from their MC 202 to improve performance and that would push the weight and loading in the other direction. Also, Allied pilots routinely misidentified MC200 as the (far sexier) MC202. They were much more likely to shoot down the former.

Look at the arguments concerning the Spitfire (wing loading 24lb/sq/ft) and the 109E ( wing loading 32lb/sq/ft) .

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This is a function of people playing favorites. The Spitfire easily out-turned the Bf 109. Some people will argue the Earth is Flat but that doesn't make it so.

Although the P-40 apparently had a better wing loading, wing loading is not the only factor in turn radius or turn ability.

There is the wing and body shape, wing span and CLmax, though I know that is a subject of intense and (mostly fruitless) debate. Also engine power made a difference in a turn and P-40F/L or K had a bit better power, depending on altitude than the MC 202. MC205 had superior power. Both P-40 and MC 202 pilots used partial flap settings to tighten turns especially at lower speed.Handling and control forces also affected maneuverability.

The pilots didn't seem to live in the same world you are describing...

.. because it was an article of faith among all P-40 pilots flying in the Med that the P-40 (and the Hurricane and the Spitfire) could easily out-turn both the Bf 109 E through G and the MC202 / MC 205. Most of the German pilots said the same thing. The tradeoff was between altitude and speed vs turn and dive. This comment by Australian Ace Bobby Gibbes from a 1993 interview is pretty typical:

:"...its [109s] performance was quite terrific. Kittyhawk could out turn it quite comfortably and if the Messerschmitt boys came in and tried to dog fight, they were gone. We could dive away from them. If we started with same speed and they dived away, we could catch them in the dive. But with climb, they could out-climb us to blazes. Our best fighting ceiling was twelve to fifteen thousand feet, above that the Kittyhawk went off badly. The 109 was good up to thirty-odd thousand feet and so always we had them sitting up above us. Almost never would we find them on our level."

This is just one typical (and short) example of combat in which they used turning to evade being shot down. This is from Ospreys "P-40 Aces of the MTO" (2002), page 34, last paragraph. Context was an early morning 24 March, the 59th FS flew a sweep back over Djebal Tebera and "encountered opposition over the target". This is from an interview with Lt Richard E. Holcomb,. who was credited with one Bf 109 damaged:

"Lt Harry Haines and I ended up in a ground-level dogfight right over the German airbase. It was quite a fight, as we were out-turning them and shooting up aeroplanes on the ground while they climbed to start the fight again. We would run for home until their cannon shots came close to Harry's tail and again we would out-turn them. I felt sure we at least two were damaged as they left the fight but we couldn't confirm them."

... but more importantly they made it back to base and survived the mission. There is incident after incident in which this exact tactic is described in various sources I have on the DAF pilots. Here is a direct link via google books to the above for those who might suspect me of making it up.

Incidentally, the air to air fighting on March 24 (in which US P-40 pilots made 10 victory claims, losing 1 fighter, and Luftwaffe reported 7 losses in total) was subject of a big debate upthread. In the Osprey book I found an extended pilot commentary from that day describing a couple of the victory claims which I'll transcribe and post later (even though that effort may not be equally appreciated by everybody).

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Schweik said:

Although the P-40 apparently had a better wing loading, wing loading is not the only factor in turn radius or turn ability.

Engine power made a difference in a turn and P-40F/L or K had a bit better power, depending on altitude than the MC 202. MC205 had superior power but a much higher wing loading.

Both P-40 and MC 202 pilots used partial flap settings to tighten turns especially at lower speed. I believe on the MC 202 it was a specific setting, on the P-40 it was kind of like a dimmer switch, there was a wheel and a switch on the control column.

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I should mention that in addition to using partial flap settings for some turns, Bf 109 also had the famous leading edge slats.

I have read a few anecdotes by Allied pilots saying essentially "normally they would not turn with us, if they did, it was usually trouble." I.e. (I think) 'experten'. Pure turning ability isn't or wasn't the only measure of maneuverability, for example Bf 109s would sometimes engage in 'rolling scissors' to get on the tail of Allied fighters in a dogfight, but only the most skilled / experienced pilots seemed able to pull that off. Quite often when they did dogfight, even from an altitude advantage, they suffered 'unacceptable casualties' and lost some experten that way as well.

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pbehn said:

I must say that the anecdotes you quote seem very much like PR blurb, very emotive and flowery language "At this point I really swore by a P-40, because I could dogfight and out turn him with ease. " Had the pilot been in combat in any other type, did he have any connection to the aviation industry?

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Of all the Tropes, pet theories, rationalizations and excuses I have ever seen to explain why a given fighter was supposedly bad in combat in spite of the evidence to the contrary, this is one of the most creative. I would love to see some evidence that this pilot had a "connection to the aviation industry". I don't know, though I consider it very unlikely.

All I do know about Lt Richard T Conly is that he was a combat veteran, a pilot with the 324th Fighter Group who was credited with a confirmed victory over an MC 202 that day. This was one of 3 or 4 detailed examples of combat with an MC 202 in the book I quoted from which I ran across while reading said book. Here is a direct link via google books since you seem to hint that I might be making it up (perhaps as part of the same Curtiss Aircraft conspiracy)

If the anecdote annoys you, maybe you could take it up with Osprey, the author (Aviation Historian Carl Molesworth) or the pilot himself or his family. Maybe you could convince him to reconsider his story and his personal experiences of combat based on your theories.

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wuzak said:

Merlin 24, which is generally similar to the V-1650-1, had the following ratings at +18psi boost (66.4inHg MAP):

Takeoff: 1,610hp @ 3,000rpm
MS: 1,640hp @ 3,000rpm @ 2,000ft
FS: 1,500 @ 3,000rpm @ 9,500ft

With 100/150 fuel the boost could be taken up to +25psi (80.8inHg MAP) and the ratings would be:
Takeoff: 1,730hp @ 3,000rpm
MS: 1,730hp @ 3,000rpm @ sea level
FS: 1,780hp @ 3,000rpm @ 4,000ft

The engines could probably take the over boost on lower grade fuels, but detonation would be a big risk.

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I don't think the Merlin 24 matches the V-1650-1 / Merlin 28, sadly it did not have quite that much power. Max is listed as 1,300 hp for takeoff and ~1,450 for WEP, though that is not boosted to 65" (I think it's 52") as in the anecdote I transcribed. I have never heard any accounts of them boosting Packard Merlin 1650-1 to 80.8" Hg but would be very interested to learn that they did or could if you know of any such sources.

S