P-40 the RAF in 1940/41

[wuzak]

The P-40 (no letter) was in production from early/mid 1940.

The first major export order was for the Armée de l'air, and was given in May 1940.

The USAAC had ordered 524 P-40s, but after the initial 200 the Army's order was suspended in order to produce the French order, which would now go to the British. This happened in September 1940.

Considering that when they got the P-40s, the RAF thought them unsuitable for combat, and were to only be used for combat in case of invasion, what effect, if any, would have exporting the initial batch of P-40s have had on the Battle of Britain?

 

[pbehn]

Absolutely none, it was inferior in climb at all altitudes, the RAF were never short of aircraft during the BoB. 200 top class pilots with dual nationality could have finished it a month or two earlier.

 

[tomo pauk]

RAF was short with pilots, especially trained pilots; supply of useful fighters already was more than meeting FC's demand. So having extra P-40s does not bring anything to the table for the British. Having P-40s instead of equal number of Hurricanes or Spitfireas also does not bring anything.

 

[Shortround6]

Thank you To Wuzak for staring the thread. It is certainly close enough to what I had in mind.

A minor correction in that the French order for for 230 Hawk 81A-1s was placed on Oct 9th 1939. Start of production was much later.
There is a lot of overlap in the P-40 story, like the British ordering 560 Hawk 87s (P-40D) in May of 1940 which is before the First French aircraft flew at the factory, which was June 6th 1940.

Wuzak is quite correct in that the first Hawk 81s/P-40s don't actually arrive in England until Sept. 1940 making their use in the BoB rather problematic.

Now even if we, for the sake of argument, allow for a time shift of several months (2-3?) and slight changes in equipment what was the actual combat capability of the early P-40 aircraft, their engines and armament/ammo as they existed in 1940? And how to they compare to what the British were already using or introducing? and lets try to keep to the facts and not made up stuff like the following.

"The Hurricane was NOT heavier than a P-40. MK I Hurricane went just under 6800lbs fully loaded. (and that is with a constant speed prop) A P-40B with the rear fuselage tank about 1/3 full and full ammo went about 7350lbs."
Load the hurry with a drop, or aux tank so it carried half as much gas as the P-40 and they are much closer add a pair of HMGs and it is heavier still. The Hurry could have guns added under the wings like the 109 and needed them to have a chance to down a bomber in one pass. The P-40 was a larger and heavier plane, but only if you discount the fact it is better armed and has like three times the combat range, about 700 miles at 70-75% throttle compared to less than 200.

Hurricanes did not use drop tank s or under wing guns in 1940 so this attempt to skew the comparison is bogus. Hurricanes shot down plenty of German bombers with their existing armament some in one pass, Some not with one pass.

Range comparison is rather skewed too. P-40B Might make 700 miles at 70% or so power but that is certainly NOT combat range as it makes no allowance for combat, or reserve for landing or even climb to a decent altitude after warming up the engine. In fact at 2280rpm and about 27-28in map the engine used 50-59 US gallons an hour and the range on 140 US gallons (after using 18 for warm up and take off) was 620 miles A P-40B could use 22 US gallons warming up, taking off and climbing to 15,000ft. RPM and MAP are for about 650hp which is even a bit under 70%.
Hurricane MK I uses about 47 Imp gal an hour (2 hours a full tank capacity which is also a bit useless) at 2600rpm and max weak mixture. At 1900 rpm (most economical) it could, in theory, stay up for 4.7 hours.
P-40 does have range advantage, just not anywhere near what is being claimed.

 

[drgondog]

The first series of external tanks for the P-40 were strictly ferry tanks, unpressurized and unsealed - and not available to the AAF until 1942

 

[Shortround6]

Thank you Drgondog.
Just for reference so we are all on the same page the Hurricane I held 94-97imp gallons of fuel internally. The P-40B held 132 imp gals and the P-40C held 114Imp gallons. Hurricane data from the pilots manual and the aircraft data card (they don't agree). P-40 data from the US Army pilots flight operating instructions.

Hurricane at 94 gallons held 71% of the fuel of a P-40B and 82% of the fuel of a P-40C so it hardly needed any extra tankage to reach 50% of the fuel of a P-40.

 

[pbehn]

I can understand a discussion of range in the battle over France and later Germany, Hurricanes and Spitfires protected the beaches at Dunkerque. They had adequate range to cover Kent.

 

[wuzak]

All things are relevant! A P-40 can out climb any bomber, does that make it quick enough?

Again, you "Define" lower altitudes inappropriately in that all the planes in this discussion can easily out climb the bombers and none of them could out clime the Me-109! So to put things in perspective;" All the Allied fighter planes could out clime all the Nazi bombers of the period, but none of the allied fighter planes could climb above the Me-109 that fought in the BoB!"

Wrong! It was not as fast [a climber] as the Hurry, which was not as fast as the Spit, but all were very much faster than the German bombers and, depending on their bomb load had more than 10,000' of advantage over them. So "High Altitude was a very relative thing and not relevant to the discussion about fighter planes Vs Bombers!

Whether or not the P-40 could out-climb a German bomber or Bf 109 is irrelevant.

The real enemy was time. That is, the warning time they got of a Luftwaffe attack against the time they needed to get to their aircraft, start it, taxi it, take off and climb to the German bombers' altitude or, if possible, above.

No point being able to out-climb a German bomber, or even a Bf 109, if the German bombers have finished their bombing and left the area before you can get to altitude.

In August of 1940 the time to climb to German bomber altitude for a RAF P-40 was > 2 months.

 

[Greyman]

The typical dispersion from the Colt-Browning was about 4" per 100 yards. The Spit's wing and it's distributed mounting system caused the normally great gun to scatter it's bullets all over the place. When mounted in the Hurricane the same gun shot to under 8.5"

This is a common Canard that is repeated often. The .50 is roughly eight times as had to tumble as the .303 which was slightly better than the 30-06 which was about half as good as the German 7.92 MM

Self sealing tanks negate all RCMG ammo! The .50 is large enough to make self sealing tanks irrelevant! The .50 cal tracer was a better incendiary round than the De Wilde incendiary in the .303. The .303 tracer was worthless at setting fire to gasoline and would not start a leak in a SS Tank.

I'd like to see the test that produced an 8.5 inch group from a Hurricane's Browning at 100 yards. I wont say its impossible - but I'm willing to bet the test isn't representative of service conditions.

The 'common canard' you refer to is supported by Orfordness Research Station firing trials. Namely:

- Vulnerability of the Me. 109 F (Fighter version) from Direct Astern of the Thrust Line
- Vulnerability of the Me. 109 F (Fighter version) from 20 deg. above Direct Astern
- The Estimated Vulnerability of a F.W. 190 A 3 from Direct Astern​

These trials demonstrate that the pilot of a German fighter is very safe from .5-inch M1 AP fire from directly astern.

The statement that self-sealing tanks negating all rifle ammunition is false. Not all self sealing tanks are created equal - some are very effective and some are practically useless. With regards to the .303 'de Wilde' round, the Chief Superintendent of Design (D. Arm. D.) had this to say in January '41:

"Should the mouth of the steel sleeve remain open, and the bullet travel nose foremost through a petrol tank, the sleeve will often cut out a round hole in the covering of the tank thus destroying the self sealing device."

 

[wuzak]

Once again, if the Brits had had the foresight to order the P-40 because of the lack of fire power in eight gunned .303 RCMGs, then they would have been available in time for the battle of Britain. America was one of the first to realize that RCMGs would not cut it in the next war. We put .50s on mass produced planes starting in the 1920s. When did the RAF see the need for bigger guns? Long after the Germans had installed crappy 20s. I just bought a book about Russian aircraft and do not know the history of their weapons development, so any info will be greatly appreciated! Sincerely. But as far as I know, the RAF were the last force on the planet to get larger guns?

The problem was that the USAAC had first dibs, and production had only started in early 1940.

By the time US deliveries were suspended in favour of export orders the Battle of Britain was all but over.

Getting P-40/Kittyhawk Is in squadron strength, the pilots and ground crew trained on the type the battle would have been over.

There is also the pesky fact that the RAF (and the USAAC) considered the P-40/Kittyhawk I to be unsuitable for combat owing to lack of armour, self sealing fuel tanks, etc.

As to the P-40's 0.50" HMGs, were the RAF using the 0.50" Browning anywhere in 1940? Or teh British in general? What does that do for the supply of rounds - do they all have to be imported from the US?

 

[pbehn]

I the Brits wanted to use 0.5 cal weapons they could have put them in the wings of a spitfire and hurricane, the idea that you order a plane based on its home nations armament is beyond stupid, what was the armament of the Mustangs (not P51s). Some Spitfires were fitted with two 0.5 in place of 4 x0.303 MGs it was not a game changer, the preference was for 4 cannon as carried by the typhoon and tempest.

 

[wuzak]

I the Brits wanted to use 0.5 cal weapons they could have put them in the wings of a spitfire and hurricane, the idea that you order a plane based on its home nations armament is beyond stupid, what was the armament of the Mustangs (not P51s). Some Spitfires were fitted with two 0.5 in place of 4 x0.303 MGs it was not a game changer, the preference was for 4 cannon as carried by the typhoon and tempest.

The Spitfire use of 0.50" mgs came late in the war - around 1944 IIRC.

The point is the supply chain. Are the guns and ammo to be built in the UK, if so when will they be available? And if not, they have to be imported, which could lead to a delay in their introduction.

I believe that the 0.50" the RAF tested before the war was a Vickers, not the US Browning, and was found unsuitable.

Also, as discussed in the other thread, aiming was an issue early in the war. With the 0.50" Browning fewer guns and less ammo could be carried, lowering teh chances of most pilots scoring hits.

 

[pbehn]

The Spitfire use of 0.50" mgs came late in the war - around 1944 IIRC.

The point is the supply chain. Are the guns and ammo to be built in the UK, if so when will they be available? And if not, they have to be imported, which could lead to a delay in their introduction.

I believe that the 0.50" the RAF tested before the war was a Vickers, not the US Browning, and was found unsuitable.

Also, as discussed in the other thread, aiming was an issue early in the war. With the 0.50" Browning fewer guns and less ammo could be carried, lowering teh chances of most pilots scoring hits.

I think you just said there was no great advantage in switching to 0.5" and I agree, I believe the idea behind the eventual chance was the trajectory being closet to the canon (not sure though)

 

[Shortround6]

The British did test the American .50 cal but the American .50 was an evolving weapon. The British tested in the early 30s or when they were doing the testing that lead to the eight .303 option.
However than means that they were testing it using the M1 ball, M1 AP and M1 tracer and so on. at some point in the late 30s the Americans changed the propellant (powder) and the bullets and picked up several hundred FPS in velocity (MV was 2500fps to 2700fps depending on source and barrel length, the water cooled AA guns had 45 in barrels, the aircraft guns had 36in barrels.) The common rounds used by the US in 1941-42 were the M2 loading's with over 2800fps. a 10% increase in velocity gives a 21% increase in kinetic energy. The guns were also barely able to reach 600rpm rate of fire and that was with short belts, the weight of long belts slowed the rate of fire and that is for the un-synchronized guns. US boosted the the rate of fire of the un-synchronized guns at some point in 1940 from the barely 600rpm to about 800rpm. There were still problems with feed, especially when pulling "G"S.

If your payload is somewhat fixed (weight of armament) you can get 3 .30/.303 Brownings for the weight of one .50 cal. You can also get 45-500 rounds of the small ammo for every 100 rounds of the .50 cal ammo.
For instance four .50 cal guns with 235 rpg went 596lbs.
eight .303 with 350rpg went 411lbs.
If you want to keep the weight of armament to somewhere around 420lbs you can have four guns with about 90rpg or you can have two guns with 430-440 rpg. or three guns (one in the cowl and one in each wing) with about 205 rounds per gun. The first option gives you 40 rounds per second at best, the second one gives you 20 rounds per second at best if the guns are in the wing and closer 15 rps if synchronized. The 3rd option gives 27-28rps.
With limited power and small airfields the weight of armament was an important consideration.

 

[Shortround6]

I think you just said there was no great advantage in switching to 0.5" and I agree, I believe the idea behind the eventual chance was the trajectory being closet to the canon (not sure though)

The .50 was a better option by 1944, better ammo and better reliability than earlier. It also matched the 20mm ballistics almost exactly (with-in a few inches) out to 600 yards or bit more which was certainly all that was needed for all practical purposes.

 

[gjs238]

Didn't the US fly Spitfires when first operating from the UK?

 

[Shortround6]

British got F2As and F4Fs with .50 cal guns. What they got for ammo or what they loaded themselves might be subject to question.

See: .50 inch Browning - British Military Small Arms Ammo

British were loading .50 cal ammo with 800 grain bullets at 2,580 fps during the 30s. US M1 Ball and derivatives used 753 grain bullets (aprox) and the high velocity M2 loading used bullets closer to 710 grains.

British also got the M1 loadings when buying ammo cash before lend-lease kicked in.

Ammo loaded to British contracts with M1 specifications had 2500fps instead of the 2800fps in the M2 loading. Remington got large contracts for British .50 cal ammo in 1940.
British like or dislike of the .50 cal has to be viewed with consideration of the ammo they were using in the 30s and 1940-41 and not what the Americans were using in 1943-44-45.

 

[Shortround6]

Didn't the US fly Spitfires when first operating from the UK?

Yep. In part because the P-38s were sent to North Africa.

 

[Mike Williams]

357 mph at 15,000 ft. and 295 mph at sea level (or 302 mph depending on source) maximum level speeds of the P-40 are very competitive for a 1940 aircraft. 3,080 fpm climb rate up to 10,000' isn't too shabby either for 1940. See Performance Chart, Curtis P-40 and Official Performance Summary. FTH is a bit lower than competitors. On the plus side it had a useful constant speed propeller and rate of roll was good.

Perhaps of interest: a Air Corps, Materiel Division Memorandum Report dated October 13, 1941 on combat trials of various pursuit airplances noted:

"P-40E vs. Spitfire: The Spitfire is a much better combat airplane than the P-40E. It has a shorter radius of turn, better rate of climb and higher speed at altitude." "General Comments: The Spitfire and Hurricane are easier for inexperienced pilots to fly than the american pursuit airplanes. The automatic boost control is a big help in that respect."

I don't seem to have an AFDU comparison at hand. That might be interesting. Anyone?

 

[wuzak]

357 mph at 15,000 ft. and 295 mph at sea level (or 302 mph depending on source) maximum level speeds of the P-40 are very competitive for a 1940 aircraft. 3,080 fpm climb rate up to 10,000' isn't too shabby either for 1940. See Performance Chart, Curtis P-40 and Official Performance Summary. FTH is a bit lower than competitors. On the plus side it had a useful constant speed propeller and rate of roll was good.

Perhaps of interest: a Air Corps, Materiel Division Memorandum Report dated October 13, 1941 on combat trials of various pursuit airplances noted:

"P-40E vs. Spitfire: The Spitfire is a much better combat airplane than the P-40E. It has a shorter radius of turn, better rate of climb and higher speed at altitude." "General Comments: The Spitfire and Hurricane are easier for inexperienced pilots to fly than the american pursuit airplanes. The automatic boost control is a big help in that respect."

I don't seem to have an AFDU comparison at hand. That might be interesting. Anyone?

Do you have anything for the P-40 performance above 15,000ft?

It would be interesting to see how it dropped off.