SHOULD the P39 have been able to handle the Zero? Was it training or performance?

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The source is wwiiaircraftperformance.org. Go there and look it up. I am comparing the P-39N (not the M or Q) to the Hellcat, both official government performance tests. Facts. Hellcat and the N had about the same speed at about the same altitude but the N vastly outclimbed the Hellcat at all altitudes.
 
Certainly not trying to confuse anyone, just trying to promote facts. My point is that we have all read all the negative statements on the P-39 for decades. Everyone here is parroting the same information "slow, no climb, couldn't climb over 12000', tumbled etc). My point is that I've been reading about WWII history for decades as you have but new information has become available (late 2012) with official government/military performance tests for the P-39, virtually all models. These are facts instead of hearsay. These facts present the P-39 in a much better light. If you have not seen these official tests, please go and look for yourself. It will change your outlook.

The reference books that I have read (virtually everyone I could get my hands on) seldom agreed on performance numbers for all the US fighters. I constantly wondered why all the discrepancies. This new information allows us to compare the official government/military data plane by plane at every altitude.

The old information you read about the P-39 not being able to get above a Zero is patently false with the N model (produced Dec '42 through April '43). The N outclimbed any model of the Zero at all altitudes by a substantial margin. At all altitudes. Look at the numbers for both planes and directly compare them. This old bromide started when writers said the P-39 couldn't intercept the Japanese Bettys escorted by Zeros. Well, NO plane can intercept another plane without early warning radar (which was ineffective until August '42) or flying patrols. But the writers didn't mention that. Now forever "the P-39 couldn't climb above the Zero". Newer information contradicts that with facts.

The P-39 was no more short legged than the P-47 which was in combat from May '43 (8th AF) and didn't even have drop tank capability until that August. P-39N was already out of production before the P-47 even entered combat.
 
wuzak said:
Which is interesting for when you compare to Spitfire V tests.

The British method seems to have been to correct the measure performance back to 95% of take-off weight. So at higher loading than the P-39N figures you quote.
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Okay, so now the British have a method of computing the "average weight per specific flight" like the US Army then, right? A Spitfire IX weighing 7500# corrected to 95% would be reduced by 7500x5%=375#. The average weight correction for the P-39N was 376# (7650-7274=376).

Is somebody actually saying that the British also used a form of "average weight". Impossible, right?
 
One more time, just for you. All airplanes weigh more at takeoff than at landing because they burn their fuel. In the P-39 this difference was 900# (120 gal). For ratios or performance calculations involving aircraft weight, the problem is what weight to use? And the difference was a substantial 900#. The plane could not fight on the runway at takeoff nor could it fight in the landing pattern. So they used a calculation (that I'm sure is a lot more complex than my "half fuel" generalization) to come to an average weight during that one flight to base their weight ratios on.

I read this somewhere and can't locate the source again, but there you go.
 
It wasn't 13 it was 15 squadrons, as per my previous post, 2 Eagle squadrons transferred to the USAAF with their Mk IX aircraft, you may have heard of the Eagle squadrons, they were formed with pilots from the USA, bless 'em.

It takes a long time to put an aircraft into service, the more squadrons you have in service the more planes need replacing due to combat loss and accidents. At the start of the battle of Britain (June) the UK had 565 S/E fighters, during the battle June to October the UK was producing circa 1000 S/E fighters.at the end we had 721 fighters. So despite producing circa 5,000 fighters the number available in squadron service increased by 156.
Document-42: Aircraft production during the Battle of Britain

It is exactly the same with any aircraft, if you take the number of P-51s in service in UK 1943/45 as a measure of production in USA you miss thousands of aircraft.
 
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And here you are confusing two things. Aircraft produced at the factories and and aircraft issued to squadrons. Not the same thing.
Each Air Force differed a bit but for the British aircraft seldom went from the factory straight to a service squadron. There were usually some sort of depot where reserve aircraft were kept and final work done on them, like live firing guns or sorting out radios. How many Spitfires were in depot at the end of the year I don't know.
Counting aircraft at the end of the year as the years production also has a few flaws as it doesn't count losses.
Like 133 squadron losing 11/12 aircraft in one day due to weather/navigation while on an escort mission for B-17s.

Still it shows that the RAF and more importantly, The USAAF had no need for the P-39 in Europe in winter/spring of 1943. The RAF was equipping 2-3 squadrons per month in the fall of 1942 with Spitfire IXs, the Spitfire VIII with wing tanks was already on order. The US had the P-47s showing up and had several thousand Merlin Mustangs on order. The American big push over the winter/spring of 1943 was North Africa.
In Jan 1943 for example, the 78th fighter group starts to re-equip with P-47Cs. It had come to the UK with P-38s but all of it's aircraft and many of it's pilots were sent to North Africa to replace losses there. By the end of January the 56th fighter group is also receiving P-47Cs (in crates).
You not only need planes, you need pilots and ground crew to form squadrons and just about everything has to be imported. Britain cannot feed itself so the rations for ground crew have to be shipped in. Equipping units with P-39s would have been an expensive luxury for very little return.
 
Great post S/R, as you probably noticed pinning down production of the Spitfire is like nailing a blancmange to a wall because the pressing needs of the conflict forced changes that weren't planned. The Mk VII and VIII were actually more advanced airframe designs than the Mk IX which started out using MkV airframes. The Mk VIII being a different airframe was designated for use abroad and was used in Malta Italy and the far east where it played its part in defeating the Arakan offensive. The first production Mk VIII rolled out in Nov 1942.

Since it is the Merlin engine fitted that was the important factor in performance the Mk VII VIII IX and XVI were essentially the same basic plane.
 

Some tests will show the weight or estimated weight of the aircraft as it climbs.
Everybody knew the planes got lighter as the fuel burned off, doing performance figures at gross weight or close to it was sort of a worst case.
As in if taking off with full tanks (or full minus the fuel needed to warm up and clear the runway) the performance will not be any worse.
It may (should) be better as fuel burns off.
Taking off with a half tank gives better numbers and may reflect what could happen in combat but also is near useless for planning intercepts.
It also gives a false impression of high altitude capability.
For example a Hurricane I at 6316lbs needs about two minutes less time to climb to 25,000ft than a Hurricane I at 6750lbs, no surprise but which number do you use when planning intercepts?
Also note that at 26,000ft the lighter plane could still climb at 990fpm while the heavier one was climbing at 810fpm roughly 80% and that service ceiling changed by about 1500ft.
The difference in the Hurricanes was not caused by fuel but I just used them to illustrate the point. Using half fuel numbers may give you numbers that are more accurate for an encounter 1/2 way through a mission. They give you crap numbers if you are caught near your own airfield.
Having worst case numbers means you may be pleasantly surprised, having best case numbers means the surprises are much less likely to be pleasant.
 

Do not bring fists to a gunfight in a fact oriented group. Please.

First a better rule of thumb for high octane aviation fuel is 6#/gallon ----------> 120 gallons -----------> 720 pounds.

Professional flight testing for Range/Speed/Climb for USAAF during WWII ALWAYS stated the condition and load out of the airframe. The guidelines you should use for Performance comparisons should begin with full internal combat load out of fuel, guns, ammo and oil.

You keep referring to 1:1 ratio of P-39 vs IJN in SWP. What are your sources?

You constantly reference the P-39N performance as superior to IJN fighters as well as, Army fighters - yet IIRC there was only One P-39 Ace in the SWP (none in North Africa) for US pilots that flew them in combat before wholesaling them to the Italians and French. By contrast there were many F-4F, P-40 aces in SWP and by Commonwealth pilots in North Africa - all in a target rich environment.

The extreme climb to altitude capability relative to other top 'in service' fighters such as F6F, Spit IX, FW 190 and Bf 109 somehow failed to materialize in the key US battles in desperate times, namely Guadalcanal and the Solomons campaigns - to the extent that even when the vaunted P-39N arrived, it was never a choice for air superiority over P-40K through L or P-38 - and remained in service in 1943 simply because the much needed P-38 and P-47 and even P-51A were not available in sufficient numbers to entirely replace them.

The VVS used them in low to mid altitude - AKAIK, never as high altitude interceptors. What do you cite as the reasons that USAAF theatre commanders used to plead for replacements? And given influx of newer P-40 and P-38 and P-47, shuttled the P-39 fleet to CAS role and short range role at that?

Perhaps, take a cut at the reasons you think that AAF pulled them from Theatre combat planning and TO&E in mid 1943 as US production of the P-51B and P-47D ramped up? Well before first deployment of the P-51A and P-51B?

If more than 'a feeling', please cite sources?

If not, I have a suggestion ---------> dive into research of the Med Air Force and Air Marshall Coningham, then into noted AWPD planners Generals Lawrence Kuter (developer of FM-100 7/43) and Muir Fairchild as the AAF doctrine for Tactical Air requirement included aircraft capable of air superiority over the battlefield in addition to CAS. These two gentlemen were Essential to the acquisition and increased Prioritization of the P-51A and Merlin P-51B over Oliver Echols objections - and for a brief time, responsible for the dedication of the first year of P-51B to TAC for Recon and CAS - before clearer heads pulled them into subordination to 8th AF in November 1943.
 
I would note that there was sometimes a variation.

drgondog said:
The guidelines you should use for Performance comparisons should begin with full internal combat load out of fuel, guns, ammo and oil.
Click to expand...

A lot of times there was a difference between "design" weight and even max clean gross weight (no external stores). The "G" load ratings were often done at "design" weight which was sometimes with less than full internal fuel and ammo for example.
For the P-39 it seems that the ammo load was 300rpg for the .30 cal wing guns for example. The ammo boxes could hold 1000rpg but the extra weight, while counted for max gross was not in "normal/design" gross weight.
This is why the conditions of the test need to be spelled out.
The Navy played an awful lot of games with weight both pre-war and early war with intercept weight loadings counting partial fuel and partial ammo loads, with full internal fuel and full ammo being called overload. Once they were in combat in the Pacific I doubt very highly if F4Fs flew off carrier decks with just 200rpg and less than full internal fuel tanks. Navy even had weight charts showing F4Fs with only two guns if carrying bombs. Another load-out that never saw the light of day in combat.

However I would agree that if not stated otherwise then full fuel, oil, guns and ammo (subject to what was considered "normal") should be assumed to be the condition of the plane. Or suitable ballast for anything not in the plane for test.
 
This is a bit of a non sequitur. The important information is not the relative climb rates it is how high you have to get and how long you have to do it. This is more a function of RADAR range, efficiency in detecting then getting airborne and cruise speed of the attacking force. If a force is detected at 20,000 ft doing 200MPH 100 miles away you have 30 minutes to get to the interception point at that altitude, getting above when climbing at less than 1000ft min is much more difficult.
 

Your N model Airacobra couldn't meet Army cooling requirements on a chilly day in October (in Dayton, Ohio of all places!) and you expect it to somehow run efficiently in the steamy-hot jungles of the Southwest Pacific???? I am quite positive that this little nugget was added to the already growing list of reasons why it was felt that this airplane was unsuited for USAAF combat operations and off-loaded to the Russians in hoards, as they were desperate and would fly anything that had two wings.

Also, that P-39N flight was at war emergency settings but I was only quoting the F6F-3 at military power settings. If we factor in the use of ADI you can add 10-15 mph to the Hellcat's top speed. I say this because 60 percent of all Hellcats had WEP by January 1944 (source: AHT) so it's not a stretch to believe that a portion of them were so equipped during the time frame you are concerned about (year 1943). I also have a test document from January 1944 which clocked an F6F-3 at 391 mph @ 25,000 feet. On top of that, the document states that the actual maximum speed of this particular Hellcat was most likely never fully realized. And with the 200+ extra horsepower it most assuredly had a far improved climb rate as well. Are you getting all of this?

And you are dead wrong about the actual weight of that particular P-39N on the 17th of October.......
 
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Most British flight test document that I have come across will give a take-off weight AND a "mean weight", which was 95% of take-off. This took into account the fuel burned during the tests. Why is it so hard to believe that take-off weight isn't the same as average weight????
 
Till the end of Dec '42 ~390 Spitfire IXs had been produced. You can double check with the link in Post 603.

How many P-39Ns had been produced in that time period?
 
Yes a gallon of gas weighs 6 pounds. It was early this morning when I was doing this math. Sorry for the error.

Please read the official performance tests for the P-39 at wwiiaircraftperformance that were made available in late 2012. If you haven't analyzed this yet it could change your views on the P-39. These official military performance tests state the loads of each plane. The P-39N test states armament of one 37mm cannon with 30 rounds, two .50 caliber MGs with 250 rpg and four .30 caliber MGs with 300 rpg. The N was fully equipped when tested. Again, the weight reflects the average fuel weight during the flight.

Only one P-39 ace, Bill Fiedler was unfortunately killed shortly after his 5th victory in an accident, a P-38 careened off the runway during takeoff and killed Fiedler sitting in his plane. Many Pacific aces got their first few kills in the P-39 before going on to P-38s. Had they kept their P-39s many more would have undoubtedly become aces. The Russians had 3 of their top 4 aces flying the P-39 and scores of aces with 20 victories or more flying the P-39 against the Luftwaffe. There were plenty of P-39 aces.

The VVS used them at low-mid altitude. This is one of my favorite myths. All the Russian combat was below 15000', right? Not really. Was there some treaty or rule that kept the Luftwaffe 109s at low altitude? Certainly not. The standard combat formation for the VVS in 1943 was the "Flying Bookshelves" or "Kuban Stairs" consisting of a squadron (12 planes) flying at three levels, 5km (16500') for the lowest four, 7km (23000') for the highest four and the remaining four in between. Not much combat over 8km (26000'). About like western Europe where the B-17 and B-24 flew at 25000' with their escort at the same altitude or a little above at 26000/26500'. The Russians' mission was intercepting German tactical bombers and escorting their own tactical bombers and both flew under 15000', but that German escort was certainly not flying that low. Plenty of combat up just about as high as either side wanted to go.

Why did the AAF pull them so quickly to be replaced by the P-38, P-47 and P-51? Please remember I'm comparing the P-39N which was produced between Dec '42 and April '43. During that period the P-38F/G had just begun combat in Dec '42 and the P-47 would not see combat until May '43 after the N was out of production. These were the AAFs turbocharged super planes that were in production but not yet in combat. They had a vested interest in playing down the P-39 accomplishments and overstating their new planes. How would it play to have the AAF saying "We're giving the Russians a great little plane here, but our Lightnings and Thunderbolts are not quite ready yet". The AAF's motto was "Better planes coming", but the better planes were not that much better if at all in their earlier models. The Lightning couldn't dive and the Thunderbolt couldn't climb, and neither were very maneuverable at all. The Thunderbolt had a very short Spitfire-like range before they got drop tanks in August '43, and then still couldn't get much into Germany proper. But the biggest problem was cost. Now there are various cost figures for these planes that all got lower as production ramped up, but the Lightning was about 2.5 times the cost of a P-39 ($50k) and the Thunderbolt was about 1.7 times. American won WWII because we could pay the cost, but if a LIghtning cost 2.5 times as much then it should have been 2.5 times as capable. Put another way, you got almost a group of P-39s for every squadron of LIghtnings, or instead of the 9500 lightnings produced you could have had almost 24000 P-39s. Nobody really looks at it this way, but that's the way it was.
 
Shortround6 said:
Bell built 299 P-39s in Dec alone, but Fighters in Britain (even in Depot) beat the heck out of fighters in Buffalo New York.
And depending on shipping space, do you send P-39s or P-47s ?????
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Castle Bromwich produced a maximum of 320 planes in a month, and produced 12, 129 Spitfires in total. It may have been able to produce more MkIX s but it is a question of logistics and marrying up engine and air frame production. In addition to producing new airframes, the ramping up of production of the latest Merlin also took time, in the absence of enough Merlin 60/70 series engines then Mk Vs were produced, in the absence of Mk VII and VIII airframes then MkIX were produced. Whereas a Mk IX was better than a MKV a Mk was better than nothing, it stayed in service until 1944.
 
Milosh said:
Till the end of Dec '42 ~390 Spitfire IXs had been produced. You can double check with the link in Post 603.

How many P-39Ns had been produced in that time period?
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9500 or so P-39s produced between January 1941 and August '44. About half went to Russia. Most of those were the superior N and Q models produced from Dec '42 which comprised about 7000 of the total 9500. N and Q differed only in wing armament (4 .30s vs 2 .50s) and since the Russians removed the wing guns the Russian N and Q were pretty much the same plane. Earlier D, F, K and L had the 12000' engines, the M, N and Q had the 15000' engines that were about 100hp better at all altitudes.
 
You continually use words like "superior" well 1,300 is superior to 1,200HP but in late 1942 early 43 the USA was introducing the P--47 and the UK the Typhoon and Griffon Spitfire, the game had moved up to 1600-2000BHP for top line fighters.
 
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