Bell P-39 Airacobra & P-63 Kingcobra.

World War II American Military
#81

Well that is kind of strange as they did NOT use, or actually they tried to use, the P-39 to intercept Japanese bombers at 20,000 and they could not but F4Fs could, and did.

And considering it was there at the first of the war then why would the USAAF not use them (it was all they had?)

Now the basic specifications for the P-39D were as follows (taken from The Fighter Aircraft Pocketbook by Roy Cross): Max speed 360 mph at 15,000 ft; Best climb 2,040 ft/min. at 10,300 ft.; Climb to 20,000 ft. 11.7 min.; Range 600 miles at economical cruise; Armament 1-37mm nose cannon, 2-.50 nose m.g., 4-.30 wing m.g.; Span 34 ft. 2 in.; Length 30 ft. 2 in.; Height 11 ft. 10 in.; Wing area 213 sq. ft.; Empty weight 6,300 lbs.; Max weight 9,200 lbs.

Now was the N that much better than the D version? Did the N have the 1,325 hp. Allison V-1710-63 engine? The D version (D-2) did.

Deaf

#82

A couple of things about the P-39/P-400 at Guadalcanal: The initial P-400s sent to Guadalcanal had British oxygen systems not compatible to the American equipment there. They had no oxygen, therefore could not operate above 15,000’ or the pilots would become disoriented or pass out. The P-400 was an early export version of the P-39 for Britain/France that were taken over by the AAF and sent to the Pacific. Second point, Guadalcanal was initially a Navy/Marine operation in the Navy’s geographical area of command. This was early in the war and the Navy wanted desperately to atone for the Pearl Harbor disaster. They viewed the few P-400s sent by the Army (AAF) as an attempt to grab some of the publicity (which it probably was) and did everything they could to discredit their participation. Typical Army/Navy political crap. P-400 had no oxygen and was overweight at 7,850# so it was relegated to ground support which it performed admirably against Japanese ground troops in the Battle of Bloody Ridge. The Navy later admitted privately that the P-400s may have actually turned the tide in that crucial battle.

P-39s WERE used to intercept high flying Jap Betty bombers at Port Moresby in New Guinea from April 1942. They had a tough time because: 1. No radar for early warning (until August), 2. Japanese superiority in pilot quality (Jap Navy carrier pilots stationed in N. New Guinea vs green 200 hour American pilots fresh out of flight school) and 3. Japanese numerical superiority (bases all along north NG coast vs 2 squadrons of P-39s at Port Moresby and one at Milne Bay). Despite those odds those boys held the Japanese out of Moresby along with the Navy victory at Coral Sea.

The Navy had much more success intercepting the Bettys at Guadalcanal for a variety of reasons. First, they had radar and an extensive net of coast watchers for early warning and were able to climb to altitude above the bombers for ideal interception conditions. The P-39 pilots had no radar (until August) and few coast watchers so they were continuously being attacked with no warning. With only two squadrons they could only fly two-man patrols and even then not all the time. Interception of high flying bombers is virtually impossible without early warning. Second, the Japanese had a much longer trip from Rabaul to Guadalcanal (over 500mi one way) vs Lae to Port Moresby (180mi one way). Their Zero escort had to use drop tanks and pilot/crew fatigue and mechanical/combat damage had a greater effect. Third, those Navy F4F carrier pilots were better than their AAF counterparts, the Navy boys had an average of more than 1,000 hours and more extensive training. Carrier pilots on both sides were much better trained than their Army counterparts for obvious reasons. 4. Japanese pilot quality had already declined because of losses at Coral Sea, Midway and New Guinea which all happened prior to Guadalcanal which began in August 1942.

Regarding P-39 vs F4F, every P-39 was faster and would climb to any altitude faster than any F4F. F4Fs had much better early warning and better pilots early in the war. Pilot manuals for both planes show time to 20,000’ as 9.1 min for P-39D and 10.0 min for F4F. P-39N climbed to 20,000’ in 6 minutes, fastest of any US plane.

N model was a big improvement over D model P-39s. There were two basic models of P-39. D through M had the V1710-35 or -63 engines with 8.8:1 supercharger gears. N and Q (same plane except for wing guns) had -85 engine with 9.6:1 gears which gave about 100 extra horsepower at medium altitudes. Doesn’t sound like much, but at 20,000’ speed increased from 348mph to 375mph, at 25,000’ increased from 324 to 370mph. N and Q represented over 75% of all P-39 production and began in November 1942. N and Q engines had 1200hp for takeoff and 1150@15,000’. D through M had 1150 or 1325hp for takeoff and 1150@12,000’, hence the better medium/high altitude performance of N/Q.

#83

If you like some technical number crunching heres a little report to keep you busy
FLIGHT INVESTIGATION OF THE VARIATION OF DRAG COEFFICIENT
WITH MACH NUMBER FOR THE BELL P-39N-1 AIRPLANE

A few manuals listed for download
ww2aircraft.net p-39-airacobra-pilots-flight-operating-instructions

Vids
P39/400 RAF
RAF P39/400
Intro to the P39
[[IntroductionToTheP-39](http://www.archive.org/details/Introduction To The P-39)

#84

The report on the variation of drag coefficient with mach number was very interesting. I didn’t understand a word of it :). I think it had something to do with drag increasing as mach number increases. Duh.

The P-39K and L flight manual was interesting, I had not seen that one before. Can you locate the P-39D or N flight manuals?

#85

The drag co-efficient one I posted as if you read through it (and get rather lost in the heiroglyphics) it seems to say that a P39N-1 could reach 600+ mph in a vertical dive.

The more interesting point though was that I have seen people claiming the top speed of a P39 was around 460mph in level flight. In the tests though the top speed in a ‘dive’ from 28000 ft was 471mph with part throttle at 10300 ft @ 2800 rpm.
Odd to me was that a full throttle dive at 3050 rpm from 30000 ft the max speed was 464 mph @ 12500 ft.

Engine fitted

Type . . . . . . . . . . . . . . . . . A l l i s o n 'J-1710-85
R a t i n g s ( b h p / r p m / a l t i t u d e )
Take-off . . . . . . . . . . . . . 1200 / 3000 / sea level
Military . . . . . . . . . . . . . 1125/3000/15,500
Normal . . . . . . . . . . . . . . 1000/2600/14,00

#86

No way the P-39 ever hit 460mph in level flight. If it had, it would have been the best fighter of WWII. The N model performance was a little over 375mph at 20,000’, about like the Hellcat only it climbed a lot better. Pretty good for early 1943. Your V-1710-85 numbers look exactly right from what I’ve read.

#87

Had not seen the P-39K and L manuals. Any idea on how to get P-39D or N manuals? Thanks in advance.

#88

Portuguese P-400s’:
My uncle, now 90, flew a P-400 in the 81st Fighter Group. He once told me about the flight of ~five A/C that, they believed “claimed engine trouble” so the pilots would be to be interned and sit out the War. The Portuguese A/F turned them over to the American Embassy in Lisbon, and they were in turn sent to Morocco, then Telepte airbase. To quote my uncle “Those guys had to fly Tail-end Charlie the whole tour”. “Not a great spot when doing strafing…they really know you’re coming”. My uncle’s getting old, and forgetful, but even years ago you couldn’t get five stories out of him. We have long forgot that many of the guys who REALLY won that war don’t want to talk about it. Comment: As a former USAF-aux SAR pilot myself, who’s logged >450 hours PIC, low level in the Rockies, in all kinds to weather, with instrument and engine problems…and instances where I had to find “a flat place to stick it”. I know what he means. He and I have shared stories we don’t tell anyone else. People would think we were bullshitting them, or trying to be a hero. It’s a place that only those of us that have had repeated trauma, blood replaced by adrenaline…can go to.

#89

Your uncle is a true American hero. Sounds like he was flying the P-400 early in the war before most of the really good German and Japanese pilots had been shot down or captured. Those guys had real courage, always outnumbered facing the absolute best the enemy had to offer in North Africa, New Guinea and Guadalcanal. That was a far cry from 1944 when American industry was producing wave after wave of new planes and the Germans and Japanese had been worn out by those old P-400s, P-39s and P-40s. The guys that came after your uncle had it much easier, newer planes, more planes, better training, and a depleted enemy. I salute your uncle, he fought the hard fight.

#90

C’mon boys, doesn’t anyone want to dispute my claim that the P-39 was the best fighter of WWII (in 1943)?

#91

hgilley,

http://www.wwiiaircraftperformance.org/mustang//p-51-37320-chart.jpg

And the go to the website
http://www.wwiiaircraftperformance.org/

and look at the blue bar and "Japan’

Go down to “Intelligence Summary 85.” The A6M is compared to the P39-D as well as others (it’s in PDF form)

And then TAIC Report No. 38 Comparative performance between Zeke 52 and P-38, P-51, P-47

and then http://www.wwiiaircraftperformance.org/sl-wade.html

and then the roll rate chart

http://www.wwiiaircraftperformance.org/naca868-rollchart.jpg

Then come back and we will talk.

Deaf

#92

The wwiiaircraftperformance site is fantastic, I have studied it for years and it never ceases to amaze me, except for the almost total lack of information about the P-39. The performance chart of P-39, P-40 and P-51 is interesting in that I have never been able to determine which plane is represented by the fastest line on the max speed chart. It is a dashed line which eliminates the P-51, and the P-40F lines are dashed and broken by the shift points of the two speed Merlin. That only leaves the P-39D and I don’t think it ever did 390mph like that chart seems to say. What is your opinion? At any rate that chart seems to say that the performance of those three planes is very similar. Keep in mind that the P-39D weight is shown as 7,700#. The Soviets flew that plane at 7,000# by eliminating the 4 useless 30 caliber wing guns, some of the non-essential armor plate (still left essential armor) and some radio equipment (essential radio eq. retained). At 7,000# the P-39 would do 382mph at 13,000’ and 370mph at 20,000’ and climb to 20,000’ in 7 minutes.

The Intelligence Summary 85 showed the P-39D-1 (at 7,850#) to be faster at all altitudes up to 25,000’ where they were equal and climb was equal up to 15,000’. Again, the Soviet modifications (which could be performed at front line bases) would have increased speed to almost 50mph faster than the Zero at 20,000’ and the Zero could no longer outclimb the P-39.

The roll rate chart was interesting in that the P-39 would out roll the Zero. Don’t try to turn with a Zero and you were fine. Stick with diving passes or dive away if the Zero was above and your life expectancy was long.

One last thing. Intelligence Summary 85 was dated December 1942. By that time the P-39N was in full production to the tune of 400/month. Why not use the N in this comparison instead of the D? The N (at 7,600#) would do 375mph at 20,000’ and climb to that altitude in 6 minutes. Compared to the Zero the N was much faster, would outclimb, outdive and outroll the Zero at all altitudes and possessed a comparable ceiling. And the N had armor plate and self sealing tanks. Oh well.

It is important to compare planes that were in combat at the same time. The P-51B was vastly superior to the P-39 but the P-51B first saw combat in 1944 (Dec '43). The P-39 was combat ready in mid 1941, two and one half years before the P-51B. Might as well say the F-22 is better than a Sopwith Camel.

These planes were in combat at the same time:

1941/1942: Spitfire V, Me109F, P-39D, P-40E, F4F Wildcat, A6M2
1943: Spitfire IX, Me109G6, P-39N (Dec 42), P-40N, P-38F (Dec 42), F4U (Feb), P-47 (May), F6F (Aug), A6M3 (Nov 42)
1944: P-51B (Dec 43)

Those are fair comparisons, especially if the P-39D is at 7,000#. Same performance as the Spit V and Me109F-1, better performance than the P-40E, F4F and A6M2.

#93

Did you take into account the acceleration rates? Or cornering speeds and altitudes? Or range?

Now you were saying best fighter in '43. Well that depends on what you consider the best attributes.

In '43 the P-39 could never escort one bomber to any target and thus could not be an escort fighter.

It could not take the fight to the enemy as it lacked range. That is it could not be an air superiority fighter.

It never could carry the bomb load of a P-47 or P-38 (and I doubt a P-51, which was not all that good a ground attack fighter.) So it could not be a top fighter-bomber.

Yes it could be a short range interceptor but we, the U.S., was more in the business of taking the fight to the enemy by mid '42 and not waiting for them to attack us.

Deaf

#94

Bomber Escort: According to the P-39Q Pilots Manual, max cruise at 25,000’ burned 62 gallons per hour. With a 75 gallon drop tank and 120 gallons internal after deducting 20 gallons for takeoff and initial climb (120+75-20=175gal) divided by 62gph=2.8hours. A B-17 cruising at 220mph traveled 616 miles or 308 miles out and 308 miles back. Based on the east coast of England 300 miles east would cover the Ruhr valley industrial complex. Remove the wing guns and put 25 gallon self sealing internal tanks in each wing where the ammo was (170+75-20=225) divided by 62gph gives you 3.6hours. That’s Berlin and back. In 1943 the P-38s had all been sent to North Africa for Operation Torch leaving only early P-47s with (unbelievably) no provision for drop tanks that could only provide escort as far as France and the Low Countries, not even to the German border. Later model P-38’s showed up in October and had much better radius. That should cover the range argument.

Bomb load was one 500 pounder. P-39 was an excellent dive bomber with no formal pilot training, just guys learning to do it on their first dive bombing mission. With the 37mm cannon it was a fearsome ground attacker providing much more destructive power than .50 caliber machine guns.

In mid-42 we were hardly taking the fight to the enemy. We had only two squadrons of P-39s in New Guinea that would have been wiped out had the Navy not won the Battle of the Coral Sea (Japs were attempting to invade Port Moresby New Guinea).

P-39 was much better plane than U.S. history gives credit. Soviets used it much better at all altitudes.

#95

Hey Deaf,

Haven’t posted in a while, tried a while back and this site was down or something, couldn’t get on. You might want to check your favorite site wwiiaircraftperformance. There is some updated P-39 information added in February 2012 about the P-39N and Q. I had not seen this before, explains why the Russians did so well with it against the Luftwaffe. Most historians would consider these docs as “primary” sources. Shows N climbing to 20,000’ in 5.8 min and 25,000’ in 8 min which would put it as the fastest climbing American plane and on a par with the 109 and Spitfire. Top speed of the Q without wing guns, which is how the Russians used it, was 393mph at 20,000’, very competitive with the 109 and 190 in early 1943. Most all the books show the N and Q at 375mph at 20,000’, 393mph would be quite an improvement. Coupled with 2630fpm climb at 20,000’ and this was a very high performance airplane for late '42 and early '43.

#96

Russian [Soviet] sources are usually fairly suspect,since the Stalinist program was never to let the facts get in the way of the ''correct " story.
The Luftwaffe basically rated the Eastern front as a rest-cure - compared to fighting the RAF/USAAF - this was shown in the loss ratios & merit award values, where victories in the west counted for more points. The Gemans kept their ''top-gun" jagd units, such as JG 26, in the west - for reasons of need…
As for fighters in service in 43, the RAF found the only plane capable - of besting the FW190 low-level strike fighters attacking Britains south-east - was the mighty 2000+hp, 4 20mm cannon Typhoon -much more potent than a dinky little P39…
& for a quick climbing, dog fighting, high altitude interceptor, - the Spitfire IX had the wee Airacobra whipped…

#97

From 486 [NZ] Sqd Typhoon combat report: “The E/A [2 FW 190s] then turned port due south & turned out to sea, where they split up, one flying south-east at sea-level & the other continuing south at about 20-30ft followed by Yellow section flying at 345/350 at sea level. Yellow 1 opened fire at long range with several short bursts of cannon fire & noticed splashes in the sea short of the E/A which immediately started to weave…Yellow 2 fired three short bursts at 200-250 yards striking the fuselage & engine. A jet of flames burst from the starboard side of the engine, the hood was jettisoned & parts of the aircraft fell away & it turned over & fell into the sea, disappearing immediately.”
The Germans initially mistook the Typhoons for P 40s, but likely wondered how they`d got them going so fast on the deck…

#98

The basic Western complaint about the P-39/63 Aircobra was its miserable high altitude climb and performance due to the limitations Allison engine. However, the airframe was very sound and like the P-40, the aircraft was very agile at low level and could out turn a Me109. Several Soviet aces flew and loved the P-39. There’s no reason to dispute this as while the initial Red Air Force was incompetently led while flying obsolete planes, they did come back and improve significantly after 1943 with better planes and pilots equal to those of the Luftwaffe, a service now buckling under the attrition of multiple theaters. There may be some exaggeration as far as numbers, but certainly the Soviet pilots loved the Aircobras while they denounced nearly every other Western Lend Lease fighter - even the Spitfire! There was in fact a final version of the P-39 that was fitted with a Merlin engine and its performance was a shade under that of the P-51 IIRC. It was just the tactical nature and low level of the air war over the East. There indeed are American and Commonwealth pilots that will attest to the skill of the elite Soviet aces - as they met them over the skies of Korea…

#99

There is no question that the toughest, & most technically advanced WW2 air combat occurred over NWE, where the US 8th AF & the 2nd TAF wrested control of the skies from the Luftwaffe in the last year of the war. The 8th AF Fighter Command required the best possible performance from its US built machines, & in fact, replaced their P38 & P47 inventory [all but one, the 56th, re-equipped with hi-po P47 Ms] with P51s. The 2nd TAF had the hottest performers from Britain, the Spitfire XIV & Tempest V, also in the air superiority role, vs the latest Nazi-tech 109K,190D & jets…
The P63, let alone the P39, could find no place here…
Indeed, the memoirs of the western fliers who had contact with Soviet airforces at this time usually describe them as a rabble, & there are also recorded episodes of ‘friendly fire’ where gung-ho USAAF units ripped into Russian formations with savagely one-sided outcomes…

#100

Stalin received no P51Ds or Tempests [well, directly from the Allies, at least - he may have taken possession of Adolf’s captured examples at Rechlin] but he was gifted quite a few P47Ds, which were capable of moving a whole lot more mud than a Airacobra or Kingcobra…