Matrix Games Forums

ORIGINAL: Mike Scholl

ORIGINAL: niceguy2005

ORIGINAL: RevRick
All thanks to one testicularly anesthetized colonel (I believe) who decided that a two stage blower was not necessary. Guy should have received a Darwin award.

He should have been forced to fly the plane in combat...at altitude.

Even with the turbo-charger the P-39 would have been a slow and not as maneuverable, but at least it would have made a much better interceptor than it was.

Actually the P-39 was faster than a Wildcat or a Zero even without the blower..., provided they would play at low altitudes. With one, it should have been able to zoom and boom and hold it's own pretty well. Wouldn't have been a world-beater, but neither were the P-40 or the F4f --- and they got the job done. Just as soon as they learned the "Cardinal Rule"..., Don't try to dogfight with a Zero or an Oscar.

Yes the P-39 is faster in horizontal flight...wasn't really what I meant...but you're right, I should have chosen my words better. What I was referring to was its overall closing ability, which was poor because of the pathetic climbing rate. A zero wants to get away all it has to do is climb.

ORIGINAL: mdiehl

Even with the turbo-charger the P-39 would have been a slow and not as maneuverable, but at least it would have made a much better interceptor than it was.

Well, it would not have been as maneuverable at low speed settings, but more maneuverable at high speed. More importantly, it WAS much faster than most Japanese planes, even without the 2-stage supercharger. The Japanese regarded the P-39 as an easy kill IF they could lure one to 20,000 feet. But Japanese pilots were notably reluctant to descend to the P-39's fighting altitude of <14K feet. Probably because the P-39 could make 375 mph roughly in the early, non 2-stage sc'd variants as compared with the A6M's 331 mph.

See above post.

Ironically, had the United States imagined that it could be bombed, it is likely that the production P-39s would have retained their superchargers, since the a.c. was intended, when originally designed, as an anti-bomber interceptor (hence the 37mm cannon).

In peacetime or in war why on earth would anyone build an interceptor that had poor climbing speed, above or below 15,000 feet? [&:]

I have read through the development of the P-39 a couple of times and the design decisions made by the USAAC is one of the most baffling of all time. I wouldn't fault Bell with this, it was the USAAC that screwed the pooch on that one.

It is amazing that despite it's drawbacks, the US STILL produced so many..The Brits weren't so stupid!&nbsp;
In July 1941, the Royal Air Force took delivery of the first of 675 P-39Ds (called the Model 14 by the RAF) which they had ordered the year before. Shortly after delivery, however, the RAF realized that the aircraft had minimal performance characteristics without a turbocharger, an accessory that had been deleted early in the aircraft's development. It was too late to cancel the order, and only one RAF squadron (No. 601) ever flew it operationally. Over 250 of the others were sent to Russia, about 200 more were transferred to the US Army Air Force in Britain, and another 200 or so were sent back to America and designated as P-400s.

ORIGINAL: niceguy2005


In peacetime or in war why on earth would anyone build an interceptor that had poor climbing speed, above or below 15,000 feet? [&:]

Politics

ORIGINAL: grumpyman

ORIGINAL: niceguy2005
In peacetime or in war why on earth would anyone build an interceptor that had poor climbing speed, above or below 15,000 feet? [&:]

Politics

Don't forget stupidity..., though in this case a projected shortage of super-chargers may have had something to do with it as well. The decision seems to have been made while the US was still "gearing up" by someone who thought "any airplane now" was better than a "good airplane later". They should have sent this fool to the South Pacific to explain his thinking to the folks who had to fly them. At least they could have had the satisfaction of beating him to a pulp.

HI!

In a game against the Jap AI, my P-39's actually have achieved more kills than they have losses (end of May 42). Fact is, against the KB's high-experience Zero's plus bonus early on no allied fighter fairs well. Later, with some accumulated experience of the P-39 units and less experience on the opposing side, its about equal.
Just bring in huge numbers, throw in some decent fighters as F4 or P40, and lets roll.

In the same game, my experience with P-36's are not bad, but I am facing huge numbers of Nates and such, nearly no more Zero's except in Rabaul. I Even have some P-35 and Brewster 339 - aces.


Anyway, I 'am looking forward to more advanced aircraft.

Have fun, everybody

HansenII - the AI is very good at putting itself in bad situations...this will make the P-39 appear to perform better, against a human who will manage his AC better it is a different story. Still as has been said its better than nothing and certainly better than Wirraway which are worse than nothing.

Docpaul, regarding the RAF, I'm not so sure it's that they were smarter as it is that they had less of a need. They had Hurris, Spits and a host of other fighters and had flown them and proven them in battle. I think like everyone else they were attracted to the promise of the aircobra, but had alternatives they could turn to when it was proven to under perform.

The US was in a different situation, not having been at war for two years, production lines and fighter designs had not yet been proven. I think by the time the P-39 was ready for deployment its development was too far along and the alternatives were not far enough along. Basically the P-39 became a stop gap. IMO the army knew even as they were getting the first squadrons operational that its time as a front line fighter would be limited.

In peacetime or in war why on earth would anyone build an interceptor that had poor climbing speed, above or below 15,000 feet?

In peacetime the YP variants with superchargers had good performance up to around 38,000 feet. I think the reasons why the superchargers were stripped out were the folliwing:

1. The USAAF assessed that there was no strategic bomber threat to the United States (in which assessment they were correct), so there was no need for a high-altitude interceptor.

2. There weren't enough superchargers to equip both new P-39s and new P-40s.

3. Therefore the P-40 was designated as the air superiority weapon (and equipped with superchargers) and the P-39 relegated to close support and low altitude ops. In fairness to the interceptor choice, most Axis bombers couldn't accurately hit anything at altitudes greater than the ones that the neutered P-39s could reach.

I have read through the development of the P-39 a couple of times and the design decisions made by the USAAC is one of the most baffling of all time. I wouldn't fault Bell with this, it was the USAAC that screwed the pooch on that one.

I completely agree. Although I do fault Bell for going with the 37mm cannon. It wasn't a particularly reliable weapon and had a fairly brief ammo load. Of course, if one *anticipated* having to shoot down the Axis equivalent of a B-17 then I suppose the choice for 37mm makes sense.

ORIGINAL: mdiehl
In peacetime the YP variants with superchargers had good performance up to around 38,000 feet. I think the reasons why the superchargers were stripped out were the folliwing:

1. The USAAF assessed that there was no strategic bomber threat to the United States (in which assessment they were correct), so there was no need for a high-altitude interceptor.

2. There weren't enough superchargers to equip both new P-39s and new P-40s.

3. Therefore the P-40 was designated as the air superiority weapon (and equipped with superchargers) and the P-39 relegated to close support and low altitude ops. In fairness to the interceptor choice, most Axis bombers couldn't accurately hit anything at altitudes greater than the ones that the neutered P-39s could reach.

I have read through the development of the P-39 a couple of times and the design decisions made by the USAAC is one of the most baffling of all time. I wouldn't fault Bell with this, it was the USAAC that screwed the pooch on that one.

I completely agree. Although I do fault Bell for going with the 37mm cannon. It wasn't a particularly reliable weapon and had a fairly brief ammo load. Of course, if one *anticipated* having to shoot down the Axis equivalent of a B-17 then I suppose the choice for 37mm makes sense.

Agree on all points..., the decisions were made for what seemed like good reasons at the time. The problems came when the situation didn't develope as forseen --- which made the decisions "stupid" in retrospect.

It's one of those facts of nature - reality is brutal, but hindsight is downright vicious.

It's often said that the P-39 didn't have a supercharger, but that's not true.&nbsp; It had a single stage, single speed mechanical supercharger, similar to early models of the Spitfire.
&nbsp;
The XP-39 had an exhaust driven turbo-supercharger, which gave it good high altitude performance.&nbsp; It had a maximum speed of 390 mph, but this was a totally unarmed, unarmored prototype, not a true fighter.&nbsp; The production fighter was 30% heavier than the XP-39.
&nbsp;
The XP-39 also had a lot of drag, and the design was changed to reduce this.&nbsp; Part of the design change was to move the supercharger intake from the side of the fuselage to the top, behind the cockpit.&nbsp; This didn't leave enough room for the turbo-supercharger (the P-39 was a very small aircraft) so the mechanical supercharger was substituted.&nbsp; It was recognized that this would hurt high altitude performance, but since prewar USAAC doctrine stressed low altitude operations, this wasn't considered a serious problem.
&nbsp;
The production P-39 was a decent fighter below 17,000 feet, but practically useless above that.&nbsp; Even though the British rejected it, they judged the P-39 to be at least the equal of the Messerschmitt Bf-109 at low altitude.&nbsp; It could out turn and out dive the Bf-109.&nbsp; It was faster and had a better roll rate than the Zero.&nbsp; All this at low altitudes.&nbsp; Unfortunately, in US service the P-39 was used as a high altitude (>20,000 ft) interceptor in 1942, and it was badly outmatched at those altitudes.
&nbsp;
Air combat in Russia was mostly below 10,000 ft, and the P-39 was very successful there.&nbsp; While the Russians used the P-39 for ground attack (they used everything for ground attack) it was primarily an air superiority fighter.&nbsp; Many Russian aces flew P-39s.
&nbsp;

I wonder if anyone has tried, but how would corsair manage against early zeroes with their bonus? Or other better,
late war planes like mustang.

It would be very easy to setup a test by going into the database editor. I suspect the Corsair would do very well...not even sure you would notice the bonus.

ORIGINAL: Mike Scholl
Agree on all points..., the decisions were made for what seemed like good reasons at the time. The problems came when the situation didn't develope as forseen --- which made the decisions "stupid" in retrospect.

Isn't this how most stupid decisions come about? [&:] Anticipation of future needs is half of management.

I think the problem was partly the militaries unwillingness to allow aircraft to specialize. The army and navy were forever in a search for that one AC that could do it all. In '39-'41, given that the US aircraft designs were lagging those of Germany, Japan (although I don't think it was realized at the time) and England, trying to build 1 plane that was air superiority fighter and bomber was a questionable undertaking. This was particularly so at the time when design methodologies called for highly iterative design/prototype/test cycles, since aeronautical engineering was so new. The P-39 was a nice try (there was a lot of innovation in the plane), but it should have been sent back to the drawing board for another iteration until they figured out how to get the high-altitude performance they wanted.

The production P-39 was a decent fighter below 17,000 feet, but practically useless above that. Even though the British rejected it, they judged the P-39 to be at least the equal of the Messerschmitt Bf-109 at low altitude. It could out turn and out dive the Bf-109. It was faster and had a better roll rate than the Zero. All this at low altitudes. Unfortunately, in US service the P-39 was used as a high altitude (>20,000 ft) interceptor in 1942, and it was badly outmatched at those altitudes.

The production P-39N/Q models were decent combat aircraft but were used nearly exclusively by the Russians who used it primarily for ground attack. They did not use it for air superiority unless the Mig-3 and Yak-9 weren't in the area as they were far better suited for those roles.

The only thing the P-39D/F models excelled at without a supercharger was speed below 10K ft. With WEP selected at 5K it was nearly as fast as the P-38. With WEP selected at 15K ft, it was slower than the A6M3 Zero.

While it had a high top speed, its ability to accelerate in level flight was extremely poor. The F4F could out accelerate it at any altitude. The P-39 took nearly 3.5 minutes to accelerate from takeoff speed to 350kts. Compare that to the Zero who could reach its maximum speed in less than one minute. Remember the P-39D/F models only had 1150 HP engines to haul around 8000lbs of weight (combat load). The Zero's 975hp engine only had to haul about 5000lbs.

It lagged behind all contemporary Japanese fighters (A6M series, Ki-43, Ki-61) in climbing ability at all altitudes. These were its primary opponents in the PNG theater.

The P-39 had the poorest turn radius of any fighter (US, Brit, Japanese) at ANY altitude. Indeed an A6M3 could complete a full 360 degree turn at 5000ft in the time it took the P-39 to turn 265 degrees. That's a whole lot of time to spend in a Zero's gunsight.

The P-39 could out roll the Zero only above 300 kts and below 10K ft. At 5000ft, the A6M3 could out roll the P-39 at any airspeed below 275kts. Only the P-40 could outroll the Zero at that speed and altitude.

For diving ability it could outdive any Japanese fighter though the Ki-61 wasn't far behind.

Chez

ORIGINAL: Mike Scholl

ORIGINAL: grumpyman

ORIGINAL: niceguy2005
In peacetime or in war why on earth would anyone build an interceptor that had poor climbing speed, above or below 15,000 feet? [&:]

Politics

Don't forget stupidity..., though in this case a projected shortage of super-chargers may have had something to do with it as well. The decision seems to have been made while the US was still "gearing up" by someone who thought "any airplane now" was better than a "good airplane later". They should have sent this fool to the South Pacific to explain his thinking to the folks who had to fly them. At least they could have had the satisfaction of beating him to a pulp.

I should have said what I mean about politics. I know I am going to over simplify things, but there was a battle between USAAC (or later the USAAF) and the regular army. The USAAC were looking to be a separate branch, a strategic bombing force and felt the regular army wanted them to be airborne artillery and spotters (a over simplification of this I know). There was a some fighting over where resources go. I think this opens the door wider for stupidity to slip through. Did it affect decisions about the P-39? I'm not sure.

pretty much tracks with what i've read. Sakai in his book noted no reluctance to attack a P-39 under any circumstances. If the Cobra had a good head of steam built up and an altitude advantage though, it could do a boom and zoom attack as good as a P-40 and that was what they had to watch out for especially given their lack of armor or self sealing fuel tanks. Ye old "beware the Hun in the Sun"

Nice to see you back around Nik.

@Chez -

The problem with your claims about P-39 and A6m acceleration, while generally correct, is that the P-39 had a much higher top speed. We can't really know how many minutes it would have required for an A6M to achieve a top speed of 350 knots (the P-39's top speed) because the A6M couldn't get there except in a dive, and that speed was above the A6M's Do Not Exceed limit. The other problem is that turn radius does not equal "time in a zero's gunsight." Briefer turn intervals simply imply that the amount of time available to the inferior turner to get a shot on the superior turner is limited. Likewise the P-39s good high speed characteristics meant that the A6M had very little time to get into position behing a P-39 before the P-39 would leave it out of range.

@Niceguy

I think the problem was partly the militaries unwillingness to allow aircraft to specialize. The army and navy were forever in a search for that one AC that could do it all. In '39-'41, given that the US aircraft designs were lagging those of Germany, Japan (although I don't think it was realized at the time) and England, trying to build 1 plane that was air superiority fighter and bomber was a questionable undertaking. This was particularly so at the time when design methodologies called for highly iterative design/prototype/test cycles, since aeronautical engineering was so new. The P-39 was a nice try (there was a lot of innovation in the plane), but it should have been sent back to the drawing board for another iteration until they figured out how to get the high-altitude performance they wanted

I don't think that is correct. The USN specialized on three types of basic combat carrier planes in the early going, and a couple of types of recon. I do not see a "one plane fits all approach" in the USN of 1941 of the form implied in the Joint Strike Fighter approach of current desires.

There is also no evidence that US aircraft design lagged Japan's. The F4F for all its poor low speed characteristics was quite successful in North Africa against ME-109s, and seems to have regularly defeated the A6M throughout the early war, and gained air supremacy where deployed starting around November 1942. On the face of it, the F4F and the P-40 were better than contemporary Axis designs excepting the Tony, the FW-190 (easily the best fighter of 1942), and the Spitfire. And if we judge Allied a.c. vs Axis a.c., the US was in fact well ahead of all the Axis powers. The Germans' effort at developing a twin-engined fighter was a miserable failure (the ME110-210-310-410 series). Contrast that with the P-38, a huge success. Japan's twin engined fighters started the war obsolete and ended the war obsolete. In 1942 the US had the F4U and F6F in design, and the P-51 in design. The only Axis aircraft really comparable to these were the FW190 and the Italian MC-202 folgore (a frequntly overlooked a.c. in such discussions).

Sakai in his book noted no reluctance to attack a P-39 under any circumstances.

Except that in his book he writes of the frustration of his wingmen that the P-39s refused to climb to the A6Ms altitude to engage. Which is a clever way of avoiding saying that the A6Ms refused to descend to 10,000 feet to engage the P-39s. Sakai's book is quite self serving, although perhaps not consciously so. One may of course sympathize with and accept that a pilot's memoirs will have a biased perspective.