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Not really an engine swap, same Allison just 8.1 internal supercharger gears. Second stage was just an add-on. Like the P-63 just move the coolant tank from behind the engine to the front, then put the second stage where the coolant tank was. Shouldn't need more cooling, same horsepower (1325/1150) as the -73 in the P-39D-2/K/L, the -95 just made it's 1150hp at 22400' instead of 12000'.Hello P-39 Expert,
Let's accept for a moment that there are no issues with an engine swap and no additional cooling requirements for the higher powered engine (which I believe to be unlikely).
How much performance improvement do you believe would result from adding 300 HP at 22,400 feet?
The P-39N with the V-1710-85 was tested at
398.5 MPH @ 9700 feet and
389.5 MPH @ 16100 feet.
Would it even break 400 MPH at altitude?
Would the performance level be more suited to a typical ETO fighter from 1942?
The armament of a single big 37mm and a couple synchronized .50 cal would still be less than adequate.
- Ivan.
Not lying, but perhaps overly optimistic as to how many enemy aircraft that they did shoot down?
I believe Ivan1GFP is close to the truth.
The engines in most P-39s the Russians had gave as much or more power at 4000 meters and under than the M-105 engines in the Yaks and Lagg-3s. The build quality was better on the P-39 (as much of difference between the paper specs of the P-39 and the aluminum ones the difference between the paper specs of the Russian aircraft and the aluminium/wood ones was often greater.)
Most Russian fighters were poorly armed by western standards. I say this because while there are certainly numbers of Russian fighters that were at least adequately armed (faint praise intended) a batch of several hundred planes is a mere handful in Russian terms.
Range of missions tended to short on the Russian front so short range was not as big a problem. The low alittidues of the vast amjority of combat meant the P-39s poor perfroamce at 15,000ft (or 20,000ft for later ones) and above was not a problem.
AS an exercise try to substitute any Russian fighter for an Allied fighter in other theaters at the same time. Lagg-3s or Yak-1s in New Guinea/Australia or Guadalcanal ??Or cross channel operations in NW Europe?
Hello Schweik,
I believe that part of the explanation here is the relative performance of the P-39 in each theatre.
On the Eastern Front, the P-39 was flying near ground level where its performance was at its peak.
The Soviets deleted the wing guns, reduced the fuel load, and seriously overboosted the engines without regard to the limitations in the manual. At low altitude, there was enough supercharger to give some extra boost.
The single 37 mm cannon and pair of cowl mounted .50 cal didn't bother them because that was pretty close to what other Soviet fighters used. 1 MG and 1 cannon was not an unusual armament for their late fighters.
Also, for the most part, Soviet fighters were not particularly fast, so the speed of a late model P-39 would have been very comparable.
On the Western Front, the battles are much higher and start off about where the P-39 runs out of steam.
The P-39 was also relatively slow at altitude, especially by the standards in the West.
In the case of the Spitfire, I believe the "real" length of the airframe never really changed. The distance from firewall to rudder hinge line was the same for all versions. The overall length changed because the engine dimensions forward of the firewall changed and the rudder aft of the hinge line changed.
In the case of the P-40 Hawk 87 series, the short tail aircraft had an offset fin that was straightened on the long tail aircraft. Part of the problem with offset surfaces is that they are really only balanced for a certain speed range. There isn't enough aerodynamic force below the speed and there is too much above the speed and both conditions need to be trimmed out to fly straight and level without control inputs.
- Ivan.
There was a fair amount of cross channel flying being done in NW europe even if it didn't really amount to much in terms of effectiveness or notable battles. The whole lean into France thing. It may have been a poor strategy or tactic but it was being done and it did affect fighter development and for the British, fighter deployment. Better fighters kept at home.I think way too much emphasis tends to be put on NW Europe in WW2. During the Battles of France and Britain it was very important. Then fighting settled down quite a bit, barring brief but bloody flareups like Dieppe, all the way until June of 1944. The direction of the war had changed by then.
A lot of the fighting in the Med, the Pacific, and the CBI was done at quite low altitude. This is why aircraft like the A6M2 and Ki-43-I which did not have good high altitude capabilities performed quite well.
Imagine say a Yak-9T available in Burma instead of a Hurricane. Yak -9T is armed with a 37mm NS-37 nose gun and a 12.7mm mg,. More than adequate to destroy any Japanese aircraft. It is 50 kph faster and far more agile than a Hurricane. I think it might have been a good swap.
There was a fair amount of cross channel flying being done in NW europe even if it didn't really amount to much in terms of effectiveness or notable battles. The whole lean into France thing. It may have been a poor strategy or tactic but it was being done and it did affect fighter development and for the British, fighter deployment. Better fighters kept at home.
The altitude ability of the A6M2 and Ki-43-I was not bad due to the power to weight ratio and low wing loading. That is not bad for their time.
If you have several planes with engines giving similar power at similar altitudes and using similar sized wings the 6000lb planes are going to perform better at higher altitudes than 7500-8000lb planes. Once the Japanese changed to improved engines with 2 speed superchargers their altitude performance got better. Of course some of the improved engine power was sucked up by better protection on the Ki-43 II and improved armament and slightly heavier construction on later A6Ms.
Not sure how good the Yak 9T would have been. The 37 is great IF you can hit with it but since the ammo for it (and the single) 12.7 are ,limited and since even a MK I Hurricane could destroy most Japanese aircraft the Yak doesn't actually bring much.
Thanks for clearing that up. It's amazing how many articles get written stating things as fact that are not. Sometimes it's difficult to figure out what's true and what's isn't.No that is not true. They had some with 20mm but most of the ones they got had the 37mm gun which they liked.
Sometimes it's difficult to figure out what's true and what's isn't.
I agree mostly with you and Ivan.I believe Ivan1GFP is close to the truth.
The engines in most P-39s the Russians had gave as much or more power at 4000 meters and under than the M-105 engines in the Yaks and Lagg-3s. The build quality was better on the P-39 (as much of difference between the paper specs of the P-39 and the aluminum ones the difference between the paper specs of the Russian aircraft and the aluminium/wood ones was often greater.)
Most Russian fighters were poorly armed by western standards. I say this because while there are certainly numbers of Russian fighters that were at least adequately armed (faint praise intended) a batch of several hundred planes is a mere handful in Russian terms.
Range of missions tended to short on the Russian front so short range was not as big a problem. The low alittidues of the vast amjority of combat meant the P-39s poor perfroamce at 15,000ft (or 20,000ft for later ones) and above was not a problem.
AS an exercise try to substitute any Russian fighter for an Allied fighter in other theaters at the same time. Lagg-3s or Yak-1s in New Guinea/Australia or Guadalcanal ??Or cross channel operations in NW Europe?
Very interesting but are you sure the p39 outclimbs the p38, any p38. In americas 100,000 there is a chart( ive seen it and similar charts elsewhere) that shows i believe the p38G with the best climb of 4200 ft per min. and the other variants weren't far behind.I agree mostly with you and Ivan.
Analyzing the P-39 has always been difficult because detailed performance information on the later N and Q models wasn't available until 2012 as far as I know.
Helps to analyze by timeline as well as theater. As with most planes performance increased over time.
In early '41 the first production P-39s were the C model without armor/self sealing tanks and the P-400 for the British that grossed an astonishing 7850# clean. It could not compete with the comtemporary SpitfireV that weighed 6500#. Astonishing, eh? The comtemporary C model weighed 7075# and would have weighed the same after the self sealing tanks and a reasonable amount of armor (140# vs 245# for the P-400) had been added because the new tanks reduced fuel by 300# and the nose .30s weren't needed. But nothing was done to the 20 C models except to use them as trainers/pilot familiarization.
First combat was defending Port Moresby, NG. AAF was not really up to speed yet, losing 17 planes just ferrying them from Australia. May '42 saw two squadrons defending Moresby against mostly G4M Betty bomber attacks escorted by Zeros from Lae. Ineffective radar and coastwatchers meant the two squadrons had to fly standing patrols to intercept the bombers who came in at 18000-22000' with escort above. The early P-39D/F/K/L had a theoretical 40mph speed advantage over the early Zeros at all altitudes but could not climb above 20000' (at 1000 feet per minute) with the now ever present drop tank. Virtually all Zero attacks came from above so these P-39s were at a severe disadvantage. In hindsight the wing guns/nose armor should have been deleted as soon as the AAF realized that virtually all missions would carry drop tanks. Had this been done the lighter P-39s would climb over 23000' at normal power with drop tank and in clean condition (combat) would outclimb contemporary Zeros at all altitudes. Bell issued weight saving instructions in May but who knows if that information ever got to the front. Moresby was saved by the Coral Sea battle and the Australians pushing the Japanese back, but the green pilots in the overwweight P-39s held their own.
Then in February came Guadalcanal and the famous P-400s (like a P-39D-1) who couldn't climb above 12000' because they had no oxygen as their British oxygen system was different than the Navy's and there was no time to wait. But all you hear is they couldn't climb above 12000'. No F4F Wildcat would outclimb any P-39 (with oxygen) at any altitude up to 25000', but you never hear that from the Navy/Marines, and Guadalcanal was largely their show.
On to North Africa in late '42 and a few squadrons of early P-39s and P-400s struggled along overweight as usual so their work was limited to mostly ground attack.
By now the (late '42) early P-38s were coming into combat finally and with all their inherent problems. The P-47 would be in combat in England in May. The AAFs turbocharged fighters were finally coming online and the P-39 (and P-40) would move into second line duty. Their only purpose was to hold the line until the turbocharged P-38 and P-47 could get into action. Except the P-39 could have dome much better all this time by just removing some items thus reducing their weight. Almost criminal to send those men into combat equipped that way.
But now in November/December '42 Allison has finally widened the V-1710 supercharger gears so they would take the 9.6 gears and the P-39N is coming out the door. The extra 100HP above critical altitude resulted in improved speed and great climb, the only planes that would climb with the N in early '43 were the Me109G and of course the SpitfireIX which would outclimb anything. The N would definitely outclimb the early Lightnings and Thunderbolts. But by now the P-39 (and P-40) were relegated to training and lend lease to the Soviets. The N and Q were the main types sent to the USSR in spring '43 and they were the same plane after removal of the wing guns and the IFF radios. Even lighter than the already well performing N the Airacobra went on to glory in the east. Oh well.
Not really an engine swap, same Allison just 8.1 internal supercharger gears. Second stage was just an add-on. Like the P-63 just move the coolant tank from behind the engine to the front, then put the second stage where the coolant tank was.
I don't know exactly what performance improvement the two stage P-39 would have. Probably a little better than the P-63 since it would have been 1000# lighter and have 35sqft less wing for the same HP. Climb should have been outstanding.
The P-39N had 100HP more at altitude than the P-39K and was 20mph faster. 300 extra HP at an even higher altitude 22400' would have made quite a difference, certainly more than 400mph. Probably a little better than a P-63A.
A P-39N was already about the same performance as the 109 and 190. A bit slower at altitude but better climb, turn and endurance. Add another 300HP at higher altitude and performance improves drastically.
The 37mm and two .50s was plenty. One hit from the cannon and goodby opponent. Just my opinions.
Anglo-American and ANZAC pilots did the same thing with their fighters in places like the Pacific and MTO... do you have any evidence the Soviets did more of these weight saving measures than anyone else?
I already pointed this out. 1 37mm and 2 nose mounted HMG was actually quite good armament unless you are trying to shoot down B-17s.
Both the P-39 and say, Yak 1B or Yak 9 were quite fast for their era, assuming they were performing to spec. Faster than say, an A6M2, a Hurricane or an MC 200.
I'm referring to the length from the propeller blade to the rudder tip. Which is I think the significant part.
Part of the issue with the P-40 was that it was routinely able to dive at speeds up to 500 mph and more, most aircraft didn't have to contend with controlling an aircraft going that fast (certainly I don't know of any Soviet planes which could). Lengthening the tail on the P-40 seemed to fix the torque problems substantially, although you did still have to use trim somewhat.
The Russian aircraft were not tailored for the eastern front. Not in the sense that they were really what the Russians wanted/desired.
They were what the Russians were able to build and they did the best the could with what they had a available and they were rather realistic about what could and could not be done with engines, fuel and guns they had available.
The Russians would have loved to build fighters using the more powerful M-106 engine and they would have loved even more to use the M-107 engine but both engines (prototypes built before the german invasion) simply could not be brought up to service reliability during the war forcing the continued use of the M-105 engine. Given the limited power and altitude capabilities of the M-105 the Russians "Tailored" their aircraft for performance by restricting the number of guns and the amount of ammo.
Manufacturing ability also entered into it as a 12.7mm gun could be built with fewer man hours than the fast firing Rusian 7.62 gun. The 7.62 was an excellent gun on paper and in service but required too much effort to manufacture and service. ... The Russians tended to like heavy armament if they could get it without sacrificeing too much else. The late model LA fighters went from 2 20mm guns to 3 guns when a new lighter weight gun was developed. The Russians wanted 3 or 4 cannon, they just knew their aircraft could not carry them without an unacceptable loss of performance.
The Russian 20mm cannon was a rather pedestrian gun. Since the cartridge was basically a necked up 12.7mm machine gun case (not exactly the same one that saw wide spread service) it was in the lower 1/2 of 20mm cartridges in regards to power. The gun itself was on the light side and not particularly durable but it was rather easy to make and reliable. However it should not be a surprise that the Russians were looking at alternatives to it. Like the larger calibers, the late war lighter 20mm allowing more guns to be fitted, the 23mm guns, especially the short 23mm cartridge guns that showed up immediately post war ( development started during the war) so the Russians were persuing multiple avenues of improved gun performance.
Hello Schweik,
From what I have been able to find, there is very little mention of loading OVER 200 rounds per .50 cal cowl gun except in one flight test and in the Russian manual on the P-39. Other reports mentioning ammunition loads have stated 200 rounds as a full load.
I believe the reduction in fuel capacity in the late model Airacobra was at the request of the Soviets and not of anyone else though there is also mention that fuel capacity can be restored if needed.
I believe the 37 mm would have been more useful against a big target such as a B-17 than in pulling a deflection shot against another fighter. It gets even worse when you consider that the ballistics of the cannon is so different from the two cowl guns that if one is one target, the other won't be.
The problem with this statement is what "for their era" means. A Hurricane or Macchi C.200 wasn't really a competitive fighter past about 1940-1941 at the latest. The faster than a A6M2 is a probably but by how much. Combat reports suggest that the Airacobra's speed advantage in combat was VERY small.
In various places, the opposition was pretty low tech (Think Italian biplanes and Ki 27) and fighters that were not suitable for front line service elsewhere could still do the job well enough. That is probably why aircraft such as the P-40, Hurricane and even Gladiator were used effectively for a while. That does not mean that they were really up to standards.
P-40N manual states maximum diving speed is 496 MPH IAS.
It also states that the aircraft will yaw to the right when diving. This suggests that the typical trim / offsets even on the P-40N are such that above a certain speed, aerodynamic effects will still cause a pull to the right and below that speed, there will be a pull to the left.
In comparison, this is not an extraordinarily high diving speed. I believe the Ki 84 manual lists 475 MPH IAS which isn't far off.