real P-39 vs ingame p-39

[pandacat]

Based on WWII Aircraft Performance, P-39 is a pretty impressive plane. And that's reflected in game as well. At some alt even faster than zero21, its main opponent, and has impressive rate of climb. Its handling ingame feels better than its contemporary p40. But why in the real history, it was an aircraft hated so much by so many. In battle of guadalcanal for example, the main dogfighting role is carried by F4F and P-39/400 was primiarily strafing ground target.

[horseback]

The P-39's reputation among the western air forces was colored by a number of things.

First, and greatest, was that it had limited range and like all Allison powered fighters without a turbosupercharger system, it quickly lost performance above 12,000 to 15,000 ft. Above those alts, it was generally thought to be nearly useless, and couldn't climb even as well as the overweight and lumbering F4F-4 Wildcat (which needed the better part of an hour to get up to 25,000 ft and still have enough fuel for combat over Guadalcanal). Tactically, it was limited in an air war that demanded range and better high altitude performance.

Second, it was rushed into the Southwest Pacific theater with undertrained pilots and support personnel, in many cases without the most basic technical documentation. Since this rush delivery to New Guinea and the Solomons included various early versions of the Airacobra, including the types originally intended for British Lend Lease, there was an extra measure of uncertainty and unreliability for the type in its initial combats. Remember that the aircraft were shipped in crates and then had to be re-assembled by personnel who had been working on other fighters like the P-35 or P-40, which were the primary types in the Philippines; the P-39 was a very new type in the inventory and had been flown primarily in the continental US.

Third, it had a reputation for being 'touchy' and unforgiving; the tendency it had for getting into a flat spin made it particularly unsuited for the novice pilots who flew it in the early combats. Pilots either loved it or (mostly) hated it, primarily because it was so sensitive. The smooth natural pilots liked it, and the heavier handed average pilots didn't, especially when they could see aircraft better suited to their skills being flown by other combat units.

Finally, it got a bad reputation early due to it being forced into roles it wasn't designed for and bad tactics ordered by senior officers who were clueless about its limitations. By the time that the pilots flying it had recognized its strengths and how to make best use of them, it was replaced by aircraft considered more reliable and longer ranged, like the P-40 and P-38.

The P-39s that flew in the Southwest Pacific rarely performed to the 'book' levels due to various combinations of the factors mentioned above, especially in the first year of American involvement; compared to the standard American taildraggers, it was small and weird looking, even when it could be flown to its limits. It was a good thing that the Russians liked them so much more than the P-40.

cheers

horseback

[Pursuivant]

Originally Posted by horseback

First, and greatest, was that it had limited range and like all Allison powered fighters without a turbosupercharger system, it quickly lost performance above 12,000 to 15,000 ft.

Good analysis.

It's especially important to recall that early in the war American fighters in the SW Pacific were often called on to be high/middle altitude interceptors against Japanese bombers flying from Rabaul or other bases on or around New Guinea, so high altitude performance and long loiter time were crucial. The P-39 just didn't have the range to be a good bomber escort or long-ranged strike fighter. And it didn't have the high-altitude performance to be a good interceptor.

On New Guinea, offensive missions required pilots to fly over the Owen Stanley Mountains, which are about 12-13,000 feet high - long distances at right about the level where the P-39 starts to lose performance. On Guadacanal, things were even worse, since any offensive operations required long high-altitude flights over water. So, the P-39's "short legs" and poor high altitude performance really grated on pilots, especially since there weren't a whole lot of good places to land.

Another minor issue that Horseback only slightly touched on was the fact that the P-39 was "weird" and "high tech" by the standards of the day. Its tricycle landing gear was different than the typical "tail-dragger" fighters and it's center-mounted engine not only gave it nasty spin recovery characteristics but also made it a maintenance headache (harder to access the engine, the long driveshift for the propeller was a hassle to swap out). Bell made a lot of design trade-offs to put a big cannon in the P-39's nose!

By contrast, the P-40 was longer-ranged, had better high altitude performance, and because it was a progressive development of the P-36, was more familiar to U.S. ground crews and was easier to maintain.

I'd also guess that U.S. pilots were more familiar with the P-40's guns and gun layout, since it had the typical U.S. arrangement of 4-6 wing-mounted 0.50 caliber guns. The 0.50 calibers worked just fine against the lightly-protected Japanese planes of the time, they fired faster, they carried more ammo and they were more or less interchangeable with the 0.50 caliber MG used by the Army ground troops, which made supply and maintenance easier.

By contrast, the Russian Front was perfect for the P-39 - lots of short-ranged, low-level action, mostly fought over land, against more heavily-protected targets where the 20mm cannon was the better weapon. Additionally, while the P-39 was somewhat tricky to maintain, it was inherently a higher-quality product than some of the Soviet fighters available. Soviet pilots appreciated the amenities that Western pilots took for granted, like reflector sights and cockpit heaters, and appreciated its relatively superior reliability.

[pandacat]

Hey horseback. Very good analysis. Btw, when you mentioned touchiness and tendency to enter flat spin, it kinda reminds me of our ingame p51s. Oh, btw, remember a while ago, you did a post on acceleration comparison? The other day, I was surfing a website call WWII aircraft performance. One of the manuals on f4f mentioned that in order to attain the same lvl of power at high alt, one needs use a lower rpm setting. The military power at low to medium requires 2500rpm, but at higher alt, the requirement drops down to 2250rpm. That kinda rang a bell when I recalled what you said about P51 getting more acceleration at 2700rpm at higher alt when speed is above 310mph. Sounds like in thinner air, you need heavier bites from the prop to get similar thrust?

[JtD]

Originally Posted by Pursuivant

By contrast, the P-40 was longer-ranged, had better high altitude performance, and because it was a progressive development of the P-36, was more familiar to U.S. ground crews and was easier to maintain.

The P-40 didn't have better high altitude performance. It essentially used the same engines, save for the differences caused by the installations, but was heavier. It was also draggier. It ended up being slower, worse climbing and with a lower ceiling than contemporary P-39's, even at high altitudes.

It was easier to fly, though - the P-39's near neutral longitudinal stability made it very difficult to handle, and spin characteristics weren't exactly forgiving. It was much easier to make a mistake in a P-39 and much harder to fix it.

However, in Il-2 it imho is one of the biggest clown wagons there are because of the absence of any the historical handling problems, yet performance that is best described as optimistic.

[horseback]

If a fighter usually works as expected, and can be kept in more optimal condition (let's be honest here; maintenance was a nightmare in the Solomons and New Guinea, regardless of which aircraft you were operating), it is vastly better performing than the aircraft with the better 'book' numbers that cannot reach them and isn't available in the minimum numbers needed because of a thousand and one maintenance problems.

The P-40 was reliable, it was predictable (if demanding) to fly, and it had a much better support system already in place, not only in the US Army Air Forces, but in the Commonwealth air forces as well. It had the confidence of its pilots, comparable (if not better) performance in actual practice to go with better range, and was therefore better suited to the first theater that the Airacobra saw combat in.

With the Soviets, the reverse was true; the P-40s rushed via Lend Lease were not well received or properly maintained by the VVS, and by Soviet standards were enormous ungainly beasts. The Airacobras benefited from the P-40's problems in terms of better care and feeding of the Allison engines because they arrived later, and from Bell's rapid commitment to support their biggest combat customer.

cheers

horseback

[gaunt1]

However, in Il-2 it imho is one of the biggest clown wagons there are because of the absence of any the historical handling problems, yet performance that is best described as optimistic.

Why, what is the problem with the P-39 ingame? Its speed and climb matches quite well to ww2aircraftperformance graphs.

[MaxGunz]

P-39D is what US pilots had. When the Russians got it they proceeded to work with Bell on improvements. See how many P-39N and Q served around New Guinea. There is a difference in weight and structure and even engine controls.

Front engine and mid engine planes act and handle differently in touchy situations. A lot of what goes on you do not feel in a sim. IRL the training is more complete than in sims. So when in a touchy situation a front-engine trained pilot may revert to training and do the wrong things then of course the plane is wrong, which last part is the similarity to sims.

It's about the same with mid or rear engine cars as opposed to front engine, also which wheels are driven. I'm happier with rear wheel drive most of the time, front or rear engine, but had one wreck that a front wheel drive could have gotten me right out of. I don't blame the car.