The P-39 a Zero Killer???

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FLYBOYJ said:
Lt. William Fiedler, he was killed when his P-39 was stuck by a P-38, I believe while on the ground.



Those losses were from all causes?
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Yes, all causes. I confess that im not 100% sure of the total losses suffered by p-39s, but their air victory totals are not great. Atleast three squadrons were in combat more or less continuously in PNG in 1942-3, stretching over roughly an 11 month period. The general rate of attrition suffered by the allied air forces was in the vicinity of 10% per month. With a force structure of 90 aircraft, the P-39s are going to be losing or writing off about 9 aircraft per month, for a total loss of about 100 aircraft in that one TO alone.

The US lost 22000 aircraft in air combat , and more than 25000 to other causes outside the US during the war. ive read they lost about 14000 aircraft iin the US itself in training accidents. Thats a total of around 61000 aircraft lost to all causes during the war. by comparison, Japanese losses were 45000, of which 17000 were not combat related. Germany lost somewhere between 75 and 110000 aircraft.

Just getting airborne will gurantee losses. Entering a disputed area like New guinea will guarantee losses on the ground and ihn the air. Operating in conditions where front lines are fluid, like the eastern front will ramp up losses even further
 

whichever way you want to cut it, the p-39 did not do well in the pacific, as the pilots that flew them readily attest to. in the air, the exchange rate was somewhere between 2:1 and 4:1, depending on who to believe. On the ground, well no way of comparing with japanese losses. However, from April 42 on, japanese air assets were heavily outnumbered....by September it was in the region of 1000 to 140, so inevitably within the microciosm of that one TO, Japanese overall losses are going to be lower. they held many advantages in the TO....most important were interior lines, better aircraft, better pilots, at least in 1942. Working against them was numbers, far better allied logistics, improving allied tactics and hradually improving pilot skills
 

What was onther impeller, apart from the 9.50 in one, that was used on the V-1710s during the ww2?

The P-40 didnn't have the turbo in the 1st place, so it could not be removed.
The unarmed XP-39 was good for mazbe 370 mph, and was immediately sent to a full scale NACA wind tunel for drag cleanup tests. NACA determined that drag from coolers was excessive, ditto for turbo iinstallation. Thez also recomended installing a more shallow cockpit glazing and a smaller wing. In case the clean-up was undertaken, NACA estimated that speed would be better than 390 mph above 20000 ft. Same speed was expected with altitude rated V-1710 (ie. single stage engine) at 15000 ft.
Once the armament and other combat equipment was installed, there is no wonder that P-39s were barely able to top 370 mph, until Allison introduced engines with 9.60:1 S/C drive ratio.
 
The Allison had a 10.25" impeller on the -143 (G6R) and -145 (G6L). It also had it on the -147 / 149 G9 R/L. Joe Yancey has both for sale and overhaul, so they aren't gone yet/

All the WWII Allisons had a 9.5" impeller.

According to Don Berlin's son, the P-40 was designed for a turbo, but was never allowed to have one until late in the game when ONE was supposedly made and performed VERY well. Unfortunately, I can't find any record of it's actual existence, so it is heresay from the Designer's son. I think it might have happened, but have no real feeling or proof either way.

Because you can't find it doesn't mean it never happened ... it means you have no proof as yet, and I don't. Will continue to look but, frankly, whether he made one or not ... it never made production, so the significance is low either way ... unless performance figures say differently.

Since I can't find proof of it's existence, I certainly can't find any performance data! ... and make NO claims about it on my own.

It remains an interesting "what if" to me, but is likely to never surface if it hasn't already. I give it little credence, but hope it is so in the end. That, at least, would enhance Don Berlin's importance as a fighter designer WAY past time. Might never happen unless someone makes a discovery of long-buried documents.
 
At low altitudes, the P-39 could be a peach of a fighter. Just ask the VVS.

The RAF found that the P-39C they tested was able to hang with a Spitfire Mk V in a climb under 10,000 ft and was faster than the Spitfire up to about 15,000 ft, but was not as nimble in switching direction (being comprable to a Mk I with fabric ailerons) or as good in the turn.

Of course, the P-39D added a heap of weight to the design (somewhere from 750-1100 lbs) with heavier armament, armour, self sealing tanks, plumbing for D/Ts and the like.

Still, the US TAIC P-39D-1 (using 52" manifold pressure giving 1325 hp sea-level/1150 at 11,200 ft, [70" was causing detonation]) vs A6M2 test (possibly slightly underperforming with only 900 hp instead of 955 hp) showed the P-39D-1 was capable of accelerating away from the Zero at any height, albeit it more slowly about 15,000 ft, and could peg it in a climb up to about 12,500 ft. Beyond this the Zero "walked away" (not encouraging phraseology for an official test).
 
GregP said:
The Allison had a 10.25" impeller on the -143 (G6R) and -145 (G6L). It also had it on the -147 / 149 G9 R/L.
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A number of the two stage engines had the 10.25" engine stage supercharger. The auxiliary stage was 12.1875".

There were some single stage engines with that impeller size - the -57 for one. Looking at Vees for Victory it would appear that most of teh G-series had the larger impeller.



It's de ja vu all over again!

The P-40 was never design to carry a turbo and never did. The definition of the P-40 project was a Hawk 75 airframe with a single speed, single stage, altitude rated V-1710 and no turbo. The reason for this was that the turbo in the XP-37 and YP-37 was unreliable and the performance was less than spectacular.

The P-40 project may have been the impetus behind the development of the altitude rated engine.

The XP-53 sort of looked like a P-40. It was to have an IV-1430 without a turbo. But since that engine was behind badly, the V-1650-1 was substituted, and it became the XP-60.

Then followed proposals for two turbocharged versions - both with the V-1710, but with different turbos. These were the P-60A (with GE turbo) and P-60B (with Wright turbo). On initial inspections the XP-60A's turbo installation was deemed to be a fire hazard, and had to be reworked. The XP-60B never happened.

There was also a proposal for the Chrysler IV-2220, the P-60C, but because that engine was also behind they stuck in an R-2800.

The XP-60 was later re-engined with the V-1650-3 as the XP-60D, but it was thought that the Merlin was needed elsewhere and it did not proceed past the prototype.

And, lastly, there was the XP-60E - another R-2800 powered version, by now bearing no resemblence to the P-40.

The XP-60A was estimated to have a top speed of 420mph, but this was never confirmed.
 
For the third time I don't say the Airacobra was a success in the Pacific, I say it contributed. Just like the P-47 after the P-51 arrived in numbers, the P-39's mission changed and it served a useful function, probably due to it being there and we had to use it.

I recommend FIRE IN THE SKY, The Air War in the South Pacific, by Eric. M. Bergerud; and Osprey's Aircraft of the Aces # 36, P-39 Airacobra Aces of World War 2.

FIRE IN THE SKY is a very good read (much like reading a novel) and the best analysis of the Air War in that area, on both sides.

Why didn't the US Pilots lighten the plane as the Reds did? Removing the .30's and ammo, could have been done easily and two .50's (forget the 37mm, replace it with a 20mm if possible - another .50 if not) on center line would have been adequate against the lightly armored Japanese planes. Of course I'm "Monday morning quarterbacking" but it seems to me that since performance was of paramount interest our Pilots would have modified the planes to achieve better performance - especially since their lives depended on it.
The men in the field did many modifications to other aircraft without approval for the brass, why not with the P-39?
 
muscogeemike said:
FWhy didn't the US Pilots lighten the plane as the Reds did?
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In theater, that would not be a decision made by pilots; that decision would normally come from a maintenance officer with concurrence from the manufacturer - that's not to say that "custom" mods weren't done in theater (some mods very "illegal" and somewhat dangerous), and few were actually done by "pilots."
 

I can't speak for the U.S. Army Air Corps practices in that particular theater of War but in the RCAF and Probably for the RAF the Pilot was the commander of the ship not his maintenance crew. He was the one that risked his life and died if there was a malfunction. It was common practice for a pilot to provide feedback to his ground crew after a flight in the aircraft that something was not working properly and needed fixing and that he expected it to be fixed ASAP assuming time and supplies permitted. If not the ground could report the a/c not ready for flight. After all they didn't want to see the pilot put into a dangerous situation. Besides regulations forbade it.

I suspect that after a number of dog fights the Pilots would collectively discuss was was working and what was not in combat. So for instance in this case I would not be surprised if they collectively got together and told the ground crew that the 37mm cannon was of no use in combat because of it's excessively slow rate of fire and propensity to jam in combat.Of course I am speaking hypothetically here and using the 37mm gun as an example of something inherently wrong with the a/c that needed fixing. This feedback could only be provided by the pilots not the maintenance crew. The Maintenance Officer I would suspect as well would want to accomodate his pilots and based on their feedback would try and make the necessary mods by perhaps advising the manufacturer of the problem and asking for a solution or alternative to using the 37mm cannon. So really changes and mods were initiated by the pilots and based on their feedback were/were not physically implemented by the ground crew.
 
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I could tell you that even a RAF or RCAF pilot would be limited on what he could have his crew do with regards to aircraft modification, repairs within approved maintenance manual data is a different story. I know back then, as in today's world, no modifications are done unless there is some kind of approved "engineering data." I've worked with both the CAF and RAAF during the past 20 years and they seem more strict on defining what types of mods or repairs involves engineering approval then the USAF and USN. What you describe in your 2nd paragraph is just about how it worked back then and even in today's world, but nothing happens "leagally" until the paperwork is approved.

I served in the USNR as a maintainer and on at least two occasions I was asked (then ordered) to attempt to repair something that was not within my maintenance authority - both times I told the powers to be to eff off and I'll be ready to stand mast with them, both times those parties stood down.
 
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As you say, any of us who have been there know that much of the book goes out the window in combat. Common sense says that survival would guide at least some Pilots and their input would be heard by commanders and Maint. people. USAAF units in New Guinea and Guadalcanal were a ways away from the flag pole.
 
muscogeemike said:
As you say, any of us who have been there know that much of the book goes out the window in combat.
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Back then, on many occasions - in today's world, you better be able to justify your actions, and even then there are many who would rather preserve their career then make a decision regarding the field alteration of a weapons system. BTW I speak for aircraft only....
 
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you have to watch when you start "lightening" as weight isnt your only consideration. you have to work within an envelope of a planes balance point. it can neither be too heavy in the nose or the tail or your flight characteristics go out the window and the plane can become unsafe for flight. that 37mm and its ammo weigh a considerable amount...replacing it with a 50 may make the plane tail heavy. you really can use the soviets as to what can be done safely and sanely to an ac. they had practices that would make other pilots and crews of most every other air force shutter. the soviets took down a lot of german planes but they lost a heck of a lot doing it.
 

My understanding is that Soviets never replaced the 37mm cannon, but deleted the wing LMGs and their ammo. That was far less CoG-sensitive thing to do, it also buys some speed through less drag. They also removed some of it's radio equipment (the P-39 carried up to 3 radio sets regularly), and probably some of it's armor.

An interesting tidbit for P-40 fans: link
 
Here is a description of modifications to a P-40E to reduce its combat weight of the 49th PG defending Darwin in 1942, authorized by the squadron CO. Note the moment contribution tabulated for each bit of equipment. The engine's position was apparently adjusted to compensate for the configuration changes that evidently included removal of two HMGs and radio, reduction of ammo, and fuel and other odds and ends. Some 49th PG pilots reportedly fought with some subset of these changes. The atached apparently describe changes to an aircraft made in June, 1942 even though the date is 9/8/42
 

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Hi Wuzak,

Yes, it IS deja vous all over again.

I stated clearly that the designer's son made the statement, not me. There IS room for a turbocharger in the P-40 if you place it correctly, and Mr. Berlin said they were allowed to build ONE. As stated by me plainly above, I can find no record of it. So it may or may not be true, I make no claim either way. When I pass on what others have said, you don't have to try to convince me of one side or the other ... I already have an opinion (not posted in here) and that won't change.

I've stuck my head into the belly of a P-47 and have seen the ducting up close and personal. I've looked in the P-40, and have actually gotten into the rear fuselage, and think you could locate a turbocharger in there, too. But I haven't bothered and won't bother to try any calculations for it since nobody in the world wants to DO it to a very valuable stock, flyable P-40.

We all know you could certainly do it with smaller modern turbo, but they didn't have them in WWII.

To me, the easiest solution to the low-to-medium altitude P-40 performance was a 2-stage Merlin. That would definitely have fit and should have been tried, but apparently wasn't. Perhaps they simply didn't think the P-40 was enough of a fighter to merit the expense of the project ... I don't know and don't care to speculate about why it was never tried.
 
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