P40 Vs all other fighters in Europe (1 Viewer)

[Escuadrilla Azul]

Those post are what I like about this forum. A thread started about the P-40 in Europe and drift to the Boeing debacle via some pretty technical detour about how temp and high afect performanceand TO, all with first hand knowledge and an informative mood. That is great.

Love you guys!

 

[Escuadrilla Azul]

Risking some groundhogery.

Could the high temp and low air density in New Guinea and Guadalcanal explain partly (beside all other known factors) explain the abysmal difference in performance (real and perceived) of the plane that can't be named and the P-40 in the PTO vs the eastern front?

 

[Shortround6]

Not quite.
The P-40 and the P-** should not change places.

If the P-40 and P-** are both running at 95 degrees then they will both perform below book value.
If the P-40 and P-** are both running at 0-32 degrees than they should both perform above book value.

Now the difference might not be identical (both planes might not drop by 3000ft) but the difference of a few hundred feet out of 3000 shouldn't change the relative standings.
LIke have the P-40 out climb the P-** in one case and climb slower in the other case (weather condition.)

Remember that the you are also comparing 3-5 planes. The P-40 and P-** are trying to climb in comparison to the A6M (and bombers?) and both are going to climb worse than the A6M (and bomber at altitude) even though the A6M is also going to climb worse. Likewise on the Russian front you are trying to see how well the P-40 and P-** climb in relation to the Bf 109 as main adversary.

open to correction.

 

[Escuadrilla Azul]

Not quite.
The P-40 and the P-** should not change places.

If the P-40 and P-** are both running at 95 degrees then they will both perform below book value.
If the P-40 and P-** are both running at 0-32 degrees than they should both perform above book value.

Now the difference might not be identical (both planes might not drop by 3000ft) but the difference of a few hundred feet out of 3000 shouldn't change the relative standings.
LIke have the P-40 out climb the P-** in one case and climb slower in the other case (weather condition.)

Remember that the you are also comparing 3-5 planes. The P-40 and P-** are trying to climb in comparison to the A6M (and bombers?) and both are going to climb worse than the A6M (and bomber at altitude) even though the A6M is also going to climb worse. Likewise on the Russian front you are trying to see how well the P-40 and P-** climb in relation to the Bf 109 as main adversary.

open to correction.

I think I didn't explain very well but nevertheless you answered my question.

I was thinking if the temp difference between NG and Cactus and the eastern front could explain the difference in performance of the P-40 and the P-40 minus one in both theathers, been both "below book value" in the tropics and "above book value" in the USSR, rather than the P-38 plus one been better than the P-40 in northern latitudes.

Anyway, thanks!

 

[tomo pauk]

My take: if one's aircraft already have problems of unfavorable power-to-weight ratio, especially at higher altitudes - talk above 15000 ft in the SW Pacific in 1942 - these problems will be even worse when trying to operate in the climate of the region.

 

[Shortround6]

Well, if our pilot friends are correct ( I am assuming they are) you may see around a 3,000ft drop in critical altitude (FTH) but this is not going to show up on the instruments.
Or rather the Manifold pressure gauge may say you are getting 42in at 2600rpm (or what ever) but you are not getting the mass of air at the pressure that you will get at a lower temperature. Watching your altimeter may show that you are not climbing at the rate of climb you are expecting for the manifold pressure.
You also have to fly a bit faster to actually equal the true airspeed and now we get into is the plane making less drag in the thinner air or is it the
increase in the incident of the wing providing more lift at similar speed cancel things out?

Your P-40 may be climbing several hundred fpm slower, but from the pilots view point that Zero (which is also climbing several hundred FPM slower) above him is still climbing faster than the P-40.

 

[FLYBOYJ]

Risking some groundhogery.

Could the high temp and low air density in New Guinea and Guadalcanal explain partly (beside all other known factors) explain the abysmal difference in performance (real and perceived) of the plane that can't be named and the P-40 in the PTO vs the eastern front?

Density altitude limitations effect ALL aircraft and are well known to the pilots operating them - and effects the enemy's aircraft as well.

 

[tomo pauk]

Density altitude limitations effect ALL aircraft and are well known to the pilots operating them - and effects the enemy's aircraft as well.

Problem might be that Japanese aircraft were already at 17-18 kft after their 300-500 mile ccruise towards the NG and Guadalcanal. Allied fighters need to take off and climb under more difficult circumstances than it will be the case in Alaska or Connecticut. P-40 and P-39 will be worse in this job (climb to 18000 ft) than the Spitfire or F4F, and even those two were not stellar.

 

[FLYBOYJ]

Problem might be that Japanese aircraft were already at 17-18 kft after their 300-500 mile ccruise towards the NG and Guadalcanal. Allied fighters need to take off and climb under more difficult circumstances than it will be the case in Alaska or Connecticut. P-40 and P-39 will be worse in this job (climb to 18000 ft) than the Spitfire or F4F, and even those two were not stellar.

Exactly. Thus the need for an interceptor with better across the board performance, possibly turbo-supercharged with a great climbing ability. Can we guess what might fill that role?

 

[Schweik]

Not quite.
The P-40 and the P-** should not change places.

If the P-40 and P-** are both running at 95 degrees then they will both perform below book value.
If the P-40 and P-** are both running at 0-32 degrees than they should both perform above book value.

Now the difference might not be identical (both planes might not drop by 3000ft) but the difference of a few hundred feet out of 3000 shouldn't change the relative standings.
LIke have the P-40 out climb the P-** in one case and climb slower in the other case (weather condition.)

Remember that the you are also comparing 3-5 planes. The P-40 and P-** are trying to climb in comparison to the A6M (and bombers?) and both are going to climb worse than the A6M (and bomber at altitude) even though the A6M is also going to climb worse. Likewise on the Russian front you are trying to see how well the P-40 and P-** climb in relation to the Bf 109 as main adversary.

open to correction.

I suspect this may actually have something to do with it. The early P-39s and P-40s were both underpowered and overloaded. Just at the tipping point. P-39 was a bit lighter but they had shorter and smaller wings

It sounds like field-stripping started a bit earlier with P-40s (as early as Java) and overboosting was already being done by Aussie units by the time of Milne Bay (summer 1942). Meanwhile the P-39s were being shipped with those extra guns in the outer wings, which I don't think they stripped those off right away. With the F4F, they were lucky in that the original F4F-3, used up to Midway, was the peppier one (before the folding wings and extra guns).

Early Allied Fighters
F4F-3 has a 38' wing span with a 260' wing area. Loaded weight was about 7,300 lbs for a 28 lb / sq ft wing loading
P-40E has a 37' wing span with a 236' wing area. Loaded weight was about 8,000 lbs for a 33 lb / sq ft (171 kg/m2) wing loading
F2A has a 35' wing span and a 206' wing area. Loaded weight was about 6,800 lbs for a 34 lb / sq fit wing loading
P-39D has a 34' wing span and a 213' wing area. Loaded weight was about 7,800 lbs for a 36 lb / sq ft wing loading (this is with the wing guns)

Early Japanese Fighters
A5M2 has a 36' wing span with a 192' wing area, loaded weight was about 3,500 lbs for a 19 lb / sq ft wing loading
A6M2 has a 39' wing span with a 241' wing area. Loaded weight was about 6,000 lbs for a 21 lb / sq ft wing loading
Ki-27 has a 37' wing span with a 200' wing area. Loaded weight was about 3,500 lbs for a 18 lb / sq ft wing loading
Ki-43 has a 35' wing span with a 230' wing area. Loaded weight was about 5,500 lbs for a 25 lb / sq ft wing loading (plus auto-flaps)

So based on that, the Japanese fighters seem much better suited to Tropical conditions.

A few lbs difference in wing loading between the Allied types may not seem like much but as I said, all the Allied fighter types were right at the tipping point, a difference of ~300 lbs or 150 hp or so seems to have made a huge jump in rate of climb, top speed etc. The Finns also experienced this with their lighter variant of the F2A. I suspect the P-39 units were lagging a bit in modifying their crates, and they already had the shortest wings and highest wing loading of the major US fighter types.

P-39 didn't do quite as badly in the Pacific as their reputation, they did get some victories (a bit over 300 claims). They definitely did better there than in the MTO. But only one (American) Ace, which is pretty telling.

Conversely, not all the P-39 units did so well in Soviet use. There were a couple which got started in the Kuban zone (which is down in the Taman peninsula on the Black Sea, in Southern Russia) in the Summer, and they didn't do so well. I wonder if climatic conditions played a role in that.

 

[Schweik]

Problem might be that Japanese aircraft were already at 17-18 kft after their 300-500 mile ccruise towards the NG and Guadalcanal. Allied fighters need to take off and climb under more difficult circumstances than it will be the case in Alaska or Connecticut. P-40 and P-39 will be worse in this job (climb to 18000 ft) than the Spitfire or F4F, and even those two were not stellar.

Sometimes, but it depended on what kind of bombing they were doing. If they were coming over with level bombers (G3M, G4M, Ki-21) they might stay at that altitude, if they were doing dive bombing, torpedo bombing or strafing they would come down much lower. The Allies also developed a fairly effective coast watcher network after the first few months and often got warning early enough to climb to altitude before the Japanese got there (even with the very slow-climbing types).

 

[Schweik]

Exactly. Thus the need for an interceptor with better across the board performance, possibly turbo-supercharged with a great climbing ability. Can we guess what might fill that role?

View attachment 654715

It helps explain why the P-38 did so well in the PTO. The extra power really helped.

 

[FLYBOYJ]

So based on that, the Japanese fighters seem much better suited to Tropical conditions.

Not really and don't over think this

As mentioned, density altitude (DA) effects EVERY aircraft. If you have an aircraft that's a poor climber to begin with, it's performance will be diminished even more based on the severity of the DA for that given day. Take off weight will definitely have a play into this, but you also have to consider how the aircraft is set up for climb performance. Available HP and wing design are also part of the equation.

 

[FLYBOYJ]

It helps explain why the P-38 did so well in the PTO. The extra power really helped.

And in general PTO pilots were better trained

 

[Schweik]

Not really and don't over think this

As mentioned, density altitude (DA) effects EVERY aircraft equally. If you have an aircraft that's a poor climber to begin with, it's performance will be diminished based on the severity of the DA for that given day. Take off weight will definitely have a play into this, but you also have to consider how the aircraft is set up for climb performance. Available HP and wing design are also part of the equation.

Right, but I'm just saying that the Japanese types seemed to have a much more comfortable margin. P-40 and P-39 are going to be starting to lose power at 10,000 ft in Tropical heat. They are close to the tipping point both for power loading and wing loading which if degraded by the equivalent of 3,000 ft, would affect takeoff and climb, right? The Japanese fighters already had an altitude advantage, but the 'comfortable zone' for the US types would be greatly compressed in high heat.

This affects not only engines but also airframes. When it comes to a stall, doesn't thinner air play a role? If you have an aircraft with a propensity to spin, and you have just effectively placed it 3,000 feet higher, wouldn't the odds of a spin go up?

The P-38 had high wing loading but a lot of extra power to call upon, and you make a good point about the training. The P-38 pilots went through operational training units. Many of the P-39 and P-40 pilots were barely trained on type. Both US 49th FG the Australian 75th FS had most of their pilots going into battle with less than 30 hours on a P-40, they literally got their training flying to the battle area (and lost half of their planes along the way in landing accidents, as many of them hadn't gotten used to retractable landing gear).

P-38 is a much more complex aircraft but I bet the extra training (often with pilots who already had combat experience in other types, like Bong and McGuire) really helped.

 

[FLYBOYJ]

Right, but I'm just saying that the Japanese types seemed to have a much more comfortable margin. P-40 and P-39 are going to be starting to lose power at 10,000 ft in Tropical heat. They are close to the tipping point both for power loading and wing loading which if degraded by the equivalent of 3,000 ft, would affect takeoff and climb, right? The Japanese fighters already had an altitude advantage, but the 'comfortable zone' for the US types would be greatly compressed in high heat.

But that "margin' would generally be the same if they were flying in 100F at 98% humidity as if they were in 32F at 10% humidity

This affects not only engines but also airframes. When it comes to a stall, doesn't thinner air play a role?

No - the aircraft will stall at the same indicated airspeeds for a given configuration.

"At higher altitudes, the air density is lower than at sea level. Because of the progressive reduction in air density, as the aircraft's altitude increases its true airspeed is progressively greater than its indicated airspeed. For example, the indicated airspeed at which an aircraft stalls can be considered constant, but the true airspeed at which it stalls increases with altitude."

If you have an aircraft with a propensity to spin, and you have just effectively placed it 3,000 feet higher, wouldn't the odds of a spin go up?

No, same as stalling.

 

[gordonm1]

Risking some groundhogery.

Could the high temp and low air density in New Guinea and Guadalcanal explain partly (beside all other known factors) explain the abysmal difference in performance (real and perceived) of the plane that can't be named and the P-40 in the PTO vs the eastern front?

I thought a major point was one type was not equipped for oxygen and limited to 12,000 feet and the other was and not limited to 12,000.

 

[FLYBOYJ]

I thought a major point was one type was not equipped for oxygen and limited to 12,000 feet and the other was and not limited to 12,000.

That would be more of an operational situation. The lack of O2 was based on the configuration of the aircraft being operated.

 

[Simon Thomas]

This affects not only engines but also airframes. When it comes to a stall, doesn't thinner air play a role? If you have an aircraft with a propensity to spin, and you have just effectively placed it 3,000 feet higher, wouldn't the odds of a spin go up?

I've got some time in a Victa Airtourer 100. When I did stalls for training, I was around 3,000 ft.
One day for giggles, my brother and I took it up to 10,000 ft. Due to its small wing area and 100 hp O-200, it has a rather poor climb rate. We got to 10,000 ft after a very long hour. ATC thought we were never going to make it.
Once we got their, we didn't know what to do - so with all the wisdom that a pair of teenagers could muster, we stalled it.
The stall was at the usual IAS, but bugger me it was different. Instead of the usual waffle and nose drop, it dropped a wing and despite almost instant full rudder to catch it - that wing kept going. It got past 90° very quickly. We eventually got right side up and wings level, but dropped a few thousand feet in the process.

Getting back to the question, any planes controls are less effective at altitude. The impact on the planes performance is likely related to the way wing loading and power loading decay with altitude.

 

[Greg Boeser]

Right, but I'm just saying that the Japanese types seemed to have a much more comfortable margin. P-40 and P-39 are going to be starting to lose power at 10,000 ft in Tropical heat. They are close to the tipping point both for power loading and wing loading which if degraded by the equivalent of 3,000 ft, would affect takeoff and climb, right? The Japanese fighters already had an altitude advantage, but the 'comfortable zone' for the US types would be greatly compressed in high heat.

This affects not only engines but also airframes. When it comes to a stall, doesn't thinner air play a role? If you have an aircraft with a propensity to spin, and you have just effectively placed it 3,000 feet higher, wouldn't the odds of a spin go up?

The P-38 had high wing loading but a lot of extra power to call upon, and you make a good point about the training. The P-38 pilots went through operational training units. Many of the P-39 and P-40 pilots were barely trained on type. Both US 49th FG the Australian 75th FS had most of their pilots going into battle with less than 30 hours on a P-40, they literally got their training flying to the battle area (and lost half of their planes along the way in landing accidents, as many of them hadn't gotten used to retractable landing gear).

P-38 is a much more complex aircraft but I bet the extra training (often with pilots who already had combat experience in other types, like Bong and McGuire) really helped.

49th Pursuit Group absorbed many survivors of the Phillipines and Java, skimmed the cream of the newly arrived replacement pilots, and early on, served in an air defense role in the Darwin area, flying a single type, armed with a single weapon type, thereby simplifying maintenance.
8th and 35th Pursuit Groups were equipped with a variety of models of Airacobra, P-400s, P-39D ( of different blocks), P-39F. These were armed with three different weapons, vastly complicating supply and maintenance requirements. Plus, their theater of operations, defending Port Moresby, and conducting offensive operations across the Owen Stanleys, was a much more challenging one. P-38 squadrons being stood up or converting from other types got to cherry pick the best and brightest veteran pilots.