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

[Shortround6]

Or perhaps Belgian technicians/gunners/engineers got to the solution earlier?
At any rate, one can buy earlier, 600-800 rpm models.

Maybe they did but something seems off. The US got the M2 up to 800rpm without much difficulty. The problem was going to 1000-1200rpm.
Look at Chinn for the number of projects and companies involved and some of the failures. The fast firing M3 had almost no interchangeable parts with the M2.
You can't even take an M2 and convert it to an M3 with a parts kit.

I would note that the Belgian 12.7mm gun saw little or no actual service?

as for the Italian gun, think of a machine gun like a piston engine. If you shorten the stroke (length of bolt travel/length of cartridge) you can raise the revolutions per minute or the rounds fired per minute while keeping the piston speed (bolt speed) about the same.
Taking the Italian gun and trying to get it fire American 12.7 ammo wich was 29mm longer than the Italian ammo wasn't going to give you a high rate of fire machine gun. Not without breaking things and figuring out how to move an heavier belt.
Try increasing the stroke on an engine 26% and turning the same max rpm?

 

[tomo pauk]

Per my earlier post, the problem with US 50cals appears to have been belt-fed wing installations. The CR32 carried guns in the fuselage while the P.24 cannons were drum fed.

Having a workable HMG is one thing. Having an operationally viable belt-fed wing installation in the latest generation of 300+mph fighters is something else. If installing multiple HMGs in the wings of high-speed fighters was so straightforward, why did it take the US until late 1942 to get it right?

Were the US wing installations of the .50 that problematic in all of the listed A/C? The P-51, once the 4 HMG set-up was the norm, yes - it was problematic due to the canted attitude of guns. OTOH, I don't believe that P-40D/E and F4F-3 was let down by their guns in 1941-42.
If there was a decision for the Hurricane to be outfitted with HMGs from the get go, there is 4 years to refine the installations before BoB.

Maybe they did but something seems off. The US got the M2 up to 800rpm without much difficulty. The problem was going to 1000-1200rpm.
Look at Chinn for the number of projects and companies involved and some of the failures. The fast firing M3 had almost no interchangeable parts with the M2.
You can't even take an M2 and convert it to an M3 with a parts kit.

I would note that the Belgian 12.7mm gun saw little or no actual service?

as for the Italian gun, think of a machine gun like a piston engine. If you shorten the stroke (length of bolt travel/length of cartridge) you can raise the revolutions per minute or the rounds fired per minute while keeping the piston speed (bolt speed) about the same.
Taking the Italian gun and trying to get it fire American 12.7 ammo wich was 29mm longer than the Italian ammo wasn't going to give you a high rate of fire machine gun. Not without breaking things and figuring out how to move an heavier belt.
Try increasing the stroke on an engine 26% and turning the same max rpm?

In caliber of 13.2mm, the model 39 was installed on the FFVS J-22.
Let's not think of the US gunsmiths and techinicians designing the airborne guns of ww2 as if they were given by Good, ie. if they needed 10 years to go from 600 rpm to 1000-1200 rpm, that every other designer team will also need 10 years. We know that even the Soviet and German gunsmiths, some of them with actual record of succesful airborne guns, sometimes went in wrong direction.

 

[Shortround6]

US had at least three teams trying to improve the M2. As I said perhaps the standards were too high. The Russians were fully prepared to junk an entire gun after it fired enough rounds for the US to allow it 6-8 jams and one or two broken parts. If the US had allowed more malfunctions/parts breakage per 1000 rounds fired (2-3 complete firings of ammunition supply in most fighters) they may have gotten a high rate of fire gun into service much quicker.

 

[Hansie Bloeckmann]

Wind-up: a joke meant to deceive someone (eg "He's winding you up" meaning "he's pulling your leg" or "he's kidding you").

Another way of saying: "He's jerking your chain".. Anyone know where that saying had its origin?? Like- Okey-Dokey??

 

[parsifal]

Thanks for the correction regarding weight savings on armour. I misread my source. it should be 250lbs.

 

[P-39 Expert]

Is this a wind up? Are you saying that if the RAF and US air forces had been given the correct graph and data then the P-39 would have been a winner in service? 601 squadron changed from Hurricane Mk IIs to P39s flew one mission with it then changed to Spitfire Mk Vb and went to Malta. The P 39 would have been no use at all in Malta. In the UK the FW 190 was superior to the Spitfire MkV forcing the Typhoon into service early. When the P51A arrived it was used because at low / medium altitudes it was a top performer, liked by all who flew it. As soon as the P 51 arrived people started figuring out how to put a Merlin in it because its only problem was altitude performance. Merlins were also put in P-40s for the same reason. Did anyone ever suggest putting a Merlin in a P-39?

No Merlin for the P-39, different mount, different attachment points, the Merlin would have had to be redesigned with a remote reduction gear, basically no. Regarding P-51, any true comparison between P-51A and P-39N with the same engines and propellers had the P-51A about 10mph faster at all altitudes, but the P-39N climbed much faster so basically a trade off. P-51 was endurance champ for sure.

 

[P-39 Expert]

Apologies to one and all as I hadn't seen this posting when I replied to the other response.

I am sorry but this is total rubbish. The P39's were ordered by the UK in September 1940 when it was already clear that the BOB had been won and of course France had fallen some time before. As a result it wasn't a case of cutting losses, or weaseling out of a contract (not a fan of the UK are you) it was because the P39 wasn't a match for the latest fighters and wasn't combat ready for Ground attack, a role it could have been very useful in. We did what we did with later Hurricanes, send them to Russia or somewhere else anywhere apart from Europe.
Just a thought did the UK pay for the P400's used by the USAAF?

The original order for P-400s by the French was March 1940, before France had fallen and well before the BOB. British added to the order and ended up assuming the whole order after France fell. Then in the fall they won the BOB and at that point invasion of Britain was impossible. Now they really don't need the planes they ordered, because their own Spit and Typhoon production is plenty with no threat of invasion. And they sure don't want to pay for them because Lend Lease was enacted the following February and they would now get any US plane they want for free (at the time). So they specified an overweight plane that if necessary they could strip (like Russia) and have a nice plane. At the time the P-39/P-400 was delivered in mid 1941 they didn't need them and didn't want to pay for them. So big stink about the plane, blah blah, was okay because the US Army desperately needed them after December 1941.

 

[tomo pauk]

No Merlin for the P-39, different mount, different attachment points, the Merlin would have had to be redesigned with a remote reduction gear, basically no. Regarding P-51, any true comparison between P-51A and P-39N with the same engines and propellers had the P-51A about 10mph faster at all altitudes, but the P-39N climbed much faster so basically a trade off. P-51 was endurance champ for sure.

Talk about ~20 mph difference P-51A vs. P-39N - 385-398 mph vs 409-415. Kinda points out how unfortunate it was that Allison didn't managed to put the reliable version of the V-1710 with 9.60:1 drive for supercharger. Here is the gun-less, well prepared P-39C with the 'faster' S/C making 406 mph: link.
The P-39Q, sans gun pods, was supposedly able to beat 400 mph. Sometimes the -85 engine was stated as with rated altitude at 15500 ft, no ram. We know that P-39s were succesful in post-war racing, despite some of competitors boasting twice the horsepower.

BTW - the comparison between the Fw 190A and P-39 is a tricky thing. We know that, in winter of 1941/42, the Fw 190A1 and A2 were good for 400+ mph at 17000-18000 ft, with full weapon set up and protection for both pilot, fuel and oil system. P-39C will not cut it performance-wise, it's protection is also lacking. It will pass another 10 months before the P-39M can do 375 mph at 15000 ft, by what time the Fw 190A3 makes 410 mph at 20000 ft. Where the P-39 shines is between sea leavel and 10000 ft.

 

[tomo pauk]

The original order for P-400s by the French was March 1940, before France had fallen and well before the BOB. British added to the order and ended up assuming the whole order after France fell. Then in the fall they won the BOB and at that point invasion of Britain was impossible. Now they really don't need the planes they ordered, because their own Spit and Typhoon production is plenty with no threat of invasion. And they sure don't want to pay for them because Lend Lease was enacted the following February and they would now get any US plane they want for free (at the time). So they specified an overweight plane that if necessary they could strip (like Russia) and have a nice plane. At the time the P-39/P-400 was delivered in mid 1941 they didn't need them and didn't want to pay for them. So big stink about the plane, blah blah, was okay because the US Army desperately needed them after December 1941.

Why push an agenda without proof? British specifying a lighter cannon in order to make fighter overweight? Typhoon prodction is plenty once BoB is finnished?Do you have facsimiles of the original documents that can prove the agenda?

 

[Shortround6]

Thanks for the correction regarding weight savings on armour. I misread my source. it should be 250lbs.

No worries,

I have misquoted and most certainly mistyped plenty of times.

 

[pbehn]

The original order for P-400s by the French was March 1940, before France had fallen and well before the BOB. British added to the order and ended up assuming the whole order after France fell. Then in the fall they won the BOB and at that point invasion of Britain was impossible. Now they really don't need the planes they ordered, because their own Spit and Typhoon production is plenty with no threat of invasion. And they sure don't want to pay for them because Lend Lease was enacted the following February and they would now get any US plane they want for free (at the time). .

The British ordered what became called "P400"s because they were told it did 400 MPH, additional planes were ordered under lend lease in 1941. When they arrived they didn't do anything like 400, as you say it was slower than the P51A and that didn't do 400MPH either. The British and the USA wanted top class fighters. If as you say, the British could have any US plane for free why wouldn't they choose the P-39 if it was as good as you say it was? As previously requested please advise what role the USA used the P-39 in and for how long?

 

[CORSNING]

The P39 had an unspectacular record against Japanese fighters. Was it an issue of pilot training against an unfamilier enemy aircraft?

YES.

Or was the performance of the Zero the P39's undoing?

Range, maneuverability and the ability to operate off carriers, then YES.

The P39 had a 30 or 40 mph speed advantage over the Zero,

I am still studying this statement. At this time I can safely say that NO
operational P-39 until the introduction of the P-39N in November 1942
had a speed advantage of more than 21 mph. at any altitude.

about the same as a Spitfire, so why couldn't the P39 use this speed and dive advantage to beat the Zero like the Hellcat did?

Before November 1942 it just did not have the engine to make it happen.
.
I apologize to everyone. I have just now stumbled across this thread and not had time
to read all post yet.

 

[Glider]

The original order for P-400s by the French was March 1940, before France had fallen and well before the BOB. British added to the order and ended up assuming the whole order after France fell. Then in the fall they won the BOB and at that point invasion of Britain was impossible. Now they really don't need the planes they ordered, because their own Spit and Typhoon production is plenty with no threat of invasion. And they sure don't want to pay for them because Lend Lease was enacted the following February and they would now get any US plane they want for free (at the time). So they specified an overweight plane that if necessary they could strip (like Russia) and have a nice plane. At the time the P-39/P-400 was delivered in mid 1941 they didn't need them and didn't want to pay for them. So big stink about the plane, blah blah, was okay because the US Army desperately needed them after December 1941.

I am afraid that you are simply digging a bigger hole for yourself.
a) What the French ordered isn't the point, the point is that the British didn't order any P39's until the BOB was effectively over in September. To pretend that we were trying to cancel an order at the sane time as we ordered them is foolish
b) You seem to believe that Typhoon production was 'plenty' in 1940, I strongly recommend you check that as the second prototype didn't fly until May 1941 entering service in late 1941
c) The UK took over all the aircraft ordered by France from the USA irrespective of type when France fell. Some such as the P36 Mohawk and the Martin Maryland were used in combat but most either did nothing or were used in third line duties such as target towing or training. The fact that the P39 was taken theoretically into RAF care in May 1940 doesn't mean that we wanted or liked them. Indeed the fact that they were not used in combat when some as mentioned earlier were speaks volumes about how poorly they were thought of
d) As far as I am aware the UK paid all it's bills for all the aircraft taken over from the fall of France even if they just rotted away on a backend airfield, there was nothing special in the way the P39 was treated. As for the claim 'So they specified an overweight plane'. Others have pointed out to you that armour to protect the pilot, self sealing fuel tanks to stop them turning into torches isn't specifying an overweight aircraft. Its the bare minimum for making them combat worthy.

 

[Shortround6]

Even the US had decided back in 1940 that planes without armor and self sealing tanks would not be counted as combat worthy.
I would also note that by the time the British had built 150 Typhoons Bell had built over 900 Aircobras (end of 1941) which makes trying to get out the P-39 contract in late 1940 or early 1941 by "specifying" an overweight plane a very risky business. The British already having been burned by the Botha, the Lerwick, the Beaufort/Taurus problem and perhaps a few other programs where drawing board or prototype aircraft failed rather miserably. Deliberately screwing up
"insurance/back up" aircraft would be the height of folly.

 

[pbehn]

Even the US had decided back in 1940 that planes without armor and self sealing tanks would not be counted as combat worthy.
I would also note that by the time the British had built 150 Typhoons Bell had built over 900 Aircobras (end of 1941) which makes trying to get out the P-39 contract in late 1940 or early 1941 by "specifying" an overweight plane a very risky business. The British already having been burned by the Botha, the Lerwick, the Beaufort/Taurus problem and perhaps a few other programs where drawing board or prototype aircraft failed rather miserably. Deliberately screwing up
"insurance/back up" aircraft would be the height of folly.

I just realised that the pesky British screwed up that other winner the Brewster Buffalo, and they used exactly the same sneaky methods.

Facing a shortage of combat aircraft in January 1940, the British government established the British Purchasing Commission to acquire U.S. aircraft that would help supplement domestic production. Among the U.S. fighter aircraft that caught the Commission's attention was the Brewster. The remaining 32 B-339 aircraft ordered by the Belgians, suspended at the fall of France, were passed on to the United Kingdom.[44] Appraisal by Royal Air Force acceptance personnel criticized it on numerous points including inadequate armament and lack of pilot armor, poor high-altitude performance, engine overheating, maintenance issues, and cockpit controls, while it was praised for its handling, roomy cockpit, and visibility.[11] With a top speed of about 323 mph (520 km/h) at 21,000 ft (6,400 m), but with fuel starvation issues over 15,000 ft (4,600 m), it was considered unfit for duty in western Europe.[11] Still desperately in need of fighter aircraft in the Pacific and Asia for British and Commonwealth air forces, the UK ordered an additional 170 aircraft under the type specification B-339E.[45] The aircraft were sent to Royal Australian Air Force, RAF and Royal New Zealand Air Force fighter squadrons in Singapore, Malaya and Burma, shortly before the outbreak of war with Japan.

 

[Shortround6]

Contracts were often complicated documents with performance spelled out and even weights spelled out with penalties (reductions in price) for failing to meet performance or weight requirements, usually a certain margin was allowed. Some US contracts allowed up to 3%. at some point a short fall in performance (each plane was test flown on one or more acceptance flights) would result in that particular plane being rejected until it was brought up to standard.

Curtiss for example lost over 10,000 dollars on the 2nd XP-46 when it failed to get close to promised performance.

No manufacturer was going to accept change orders from a customer that would severely impact performance without renegotiating the contract weights and performance. TO do otherwise could result in bankruptcy.

 

[Juha2]

This is how comrades saw things
I don't have Fw 190 A-6 figures but A-5

 

[buffnut453]

Were the US wing installations of the .50 that problematic in all of the listed A/C? The P-51, once the 4 HMG set-up was the norm, yes - it was problematic due to the canted attitude of guns. OTOH, I don't believe that P-40D/E and F4F-3 was let down by their guns in 1941-42.

Yes, the problems were very real in all the types mentioned. Read Bill Bartsch's "Doomed at the Start" for accounts of the P-40s in the Philippines for the number of times gun stoppages prevented engagements. On the USN side of things, Lundstrom's "The First Team" makes it clear that the problems with the F4F's gun installation were not fully resolved until the latter half of 1942 (which makes the F4F's successes in combat prior to that point even more remarkable, IMHO).

If there was a decision for the Hurricane to be outfitted with HMGs from the get go, there is 4 years to refine the installations before BoB.

But that's applying hindsight again. When the Hurricane was ordered, the British didn't KNOW that they had 4 years' breathing room. They had to be ready for combat ASAP. Attempting to re-arm the entire Fighter Command force with HMGs when war was expected imminently would not be a sensible move, and a partial re-armament of only certain units would introduce significant logistical challenges under combat conditions. Note that cannons were only rolled out in any numbers AFTER the Battle of Britain was effectively won.

 

[buffnut453]

The aircraft were sent to Royal Australian Air Force, RAF and Royal New Zealand Air Force fighter squadrons in Singapore, Malaya and Burma, shortly before the outbreak of war with Japan.

Just a slight bit of pedantry but most Buffalo squadrons were officially RAF units, the only exception being 21 Sqn RAAF. There were 2 Article XV squadrons, 453 and 488 which later became RAAF and RNZAF units respectively but, at the time of Buffalo usage, were still strictly speaking RAF units manned with Australian and New Zealand personnel. Like I said...pedantry!

 

[wuzak]

You are truly an expert on crankshafts. My source for the 15 minutes is wwiiaircraftperformance.net. The actual government performance docs. Check them if you like.

The 15 minute rating may have been for 3000rpm at lower boost than combat power.