SHOULD the P39 have been able to handle the Zero? Was it training or performance?

[wuzak]

In actual Practice, the time to climb test was at maximum power available by the 'book' - and does not understate anything. That specific test was performed to get an idea what the airplane could be expected to do for the weight and balance conditions cited in the test.

The primary reason was to gauge interception capability and often flown in AAF 'Fighter Condition' of reduced fuel and ammo and no external stores.

Would several climb tests at military power be undertaken starting at different altitudes, to see the climb response when already in the air?

 

[Shortround6]

Ok, I am going to try to list P-39 climb rates.

model..........weight............altitude............power...............FPM
P-39D...........7525...............15,000............865.................1880
P-39D...........7525...............20,000............710.................1300
P-39D...........7525...............25,000............585...................800
P-39M...........7430...............15,000..........1040.................2640
P-39M...........7430...............20,000............880.................2000
P-39M...........7430...............25,000............725.................1400
P-39N...........7274...............15,000...........1060.................3340
P-39N...........7274...............20,000............885..................2630
P-39N...........7274...............25,000............745..................1940
P-39Q...........7821...............15,000...........1050.................2840
P-39Q...........7821...............20,000............882..................2200
P-39Q...........7821...............25,000............740..................1570
P-63A...........8286...............15,000............UNK..................3210
P-63A...........8286...............20,000............UNK..................2800
P-63A...........8286...............25,000..........<1150?................2200

The P-39D was using 2600rpm and not 3000rpm like the other planes.
The P-39 M, N and Q all used essentially the same engine, the 9.60 supercharger gear model although the P-39M used a 2.0 reduction gear to the prop and the N & Q used a 2.33, so we have different props and perhaps different propeller efficiency.
P-63 is actually the XP-63A. power figures not given in climb chart but engine rated at 1150hp at 22,400ft with no RAM Power at 15,000 and 20,000 should be greater. XP-63A figures may not be from test instruments?

all figures from the tests at WWII Aircraft Performance

I chose these altitudes because they pertain to the high altitude intercept and/or escort scenarios and because, for the P-39s at least, WEP would not be a factor. As for the weight difference between the D and M, there is roughly a 75lb weight difference between the Aeroproducts hydraulic propeller and the Curtiss electric propeller.

Make of them what you will.

 

[Shortround6]

The P-38 is considered to have excellent range. It held 150gal/engine internal. The P-39 held 120. After deducting the Reserve (for T/O and climb to 5000') of 25gal for the P-38 and 16 gal for the P-39 the useable fuel for both planes was 125 for the P-38 and 104 for the P-39. 21 whole gallons. The P-38 had a 165 gallon drop tank/engine and the P-39 had drop tanks of 75gal, 110, 158 and 175gal available. Range could have been increased to P-38 levels if needed.

More FUN FACTS?

How about reading the manuals instead of wild guesses based on such a flawed premise?

P39Q at 200mph IAS at 20,000ft burned 41 gallons an hour. or 4.9miles per gallon.
A P-38F at 190mph IAS at 20,000ft burned 67 gallons an hour or 2.8 miles per gallon.

But wait it gets better

P-39Q at 222mph IAS at 20,000ft is turning 2600rpm and burning 60 gallons an hour 3.07mpg
A P-38F at 225mph IAS at 20,00ft has engines turning at 2150rpm and is burning 83 gph(? chart is fuzzy) for 2.7MPG

These figures are for clean aircraft.
So, assuming the P-38F needs 80 gallons for take-off climb and finding it's own airfield and the magic P-39 only needs 16 we have, at 222-225IAS at 20,000ft the P-38F flying 594 miles while the P-39Q flies 319 miles.

The only way you are going to get a P-39 to fly as far as a P-38 is to tow it.

 

[Shortround6]

For any new members who haven't explored this site fully yet (and it is Huge)

scores if not hundreds of manuals can be found here.

Other Mechanical Systems Tech.

 

[DarrenW]

Sorry, but I'm not going away. I'll keep giving you the facts as long as you want to listen.

We like facts a lot around here. And now that it's quite apparent the P-39N-1 tested on 17 October 1942 had the reduced fuel capacity, how will your "facts" change to suit your flimsy arguments? And listening is a two way street, are you willing to listen to the facts as well?

 

[Peter Gunn]

I agree. But to promote your favorite plane I'm pretty sure that you wouldn't pick an avatar with the Oscar shooting down the Buffalo, now would you? Even though it happened on occasion, through no fault of the pilot or aircraft involved....

Hey now, let's not go casting aspersions on the Buff... them's fightin' words.

 

[DarrenW]

P-39Q at 222mph IAS at 20,000ft is turning 2600rpm and burning 60 gallons an hour 3.07mpg
.

So in a nutshell the P-39Q (or N, take your pick), wouldn't have more than about an hour or so of flight time available at that altitude in a clean condition, and maybe about two hours with the 75 gallon drop tank. And in order to get that sort of endurance you better hope you don't get in a fight along the way. A 200 mile radius is nothing to write home about, especially for an aircraft doing supposed escort work.

 

[DarrenW]

Hey now, let's not go casting aspersions on the Buff... them's fightin' words.

No way Peter, I happen to be a big fan of the Buff!

 

[Ascent]

Actually I read an article by a pilot who flew Spit V's in the Med. On his first flight just after takeoff he got intercepted by a P-39 and got "shot down" multiple times while he was trying to build up some airspeed.

Of course, if he had been flying a Clipped and Cropped Spitfire V it might have been a different story.

I love that P-39 artwork partially because it reminds me so much of a cover from a "Men's" magazine I saw in the 60's Very similar kind of a painting, a P-39 pilot opening the door and entering his airplane as enemy aircraft approach in the sky. Except that also scrambling into their Airacobras in the background were a bunch of beautiful scantily clad women.

Any aircraft that's just taken off and struggling for speed and altitude is a sitting duck for anything already airborne.

 

[pbehn]

We like facts a lot around here. And now that it's quite apparent the P-39N-1 tested on 17 October 1942 had the reduced fuel capacity, how will your "facts" change to suit your flimsy arguments? And listening is a two way street, are you willing to listen to the facts as well?

Every "fact" presented is a masterpiece of omission. Range always the one with the most fuel, power always at the highest rating regardless of time. Rate of climb for the lightest etc etc. There is a flat out denial of any stall spin characteristics even though "aircraftperformance" has a report saying it should never be spun or snap rolled. The plane gave no warning of stall (in the manual) and had a landing speed of 100-110 MPH, how do you do a wheels up landing? The performance quoted by S/R of the D model is abysmal. The P39 was not an equal of the Spitfire MkV in most respects indeed hardly better than a Hurricane in most. It wasn't an equal of the F4F let alone later US fighters. It was a pup, not as good as any front line allied fighter in 1942 but better than some Soviet fighters which is why it was given to the Russians.

 

[Elmas]

I like the conclusions to the test on the P39, a bit odd for a single engine combat plane. combat

1. The P-39 should not be spun intentionally under any circumstances.

2. The P-39 should not be snap rolled as the roll usually ends in a spin.

3. The best spin recovery is to simultaneously apply opposite rudder and neutralize the stick.

4. Power should be cut immediately if a power on spin is entered.

5. Care must be excercised during the recovery to prevent an accelerated stall and re-enty into the spin.

6. The wing tip spin chute does not aid recovery of the P-39Q from a flat spin.



Reading the report, the pilot bailed out as a result of 6
www.wwiiaircraftperformance.org/P-39/P-39Q_Spin.pdf

An Italian pilot recalls: "... I owe my life to the fact that I never let myself try to do acrobatics with the P-39 ."
I can't find the link anymore, unfortunately.

 

[pbehn]

An Italian pilot recalls: "... I owe my life to the fact that I never let myself try to do acrobatics with the P-39 ."
I can't find the link anymore, unfortunately.

Incredibly it was used as a training aircraft, I don't know what sort of training though.

 

[P-39 Expert]

So what was the climb performance and air speed while climbing with 110 external tank?

Climb with tank is not shown on P-39N test, so I don't know for sure.

The graph below is for the P-39K and is representative of the earlier P-39s (D,F,K and L) with the 8.8 supercharger gears and weighing approximately 7650#. As you can see, the dotted line is with belly tank, the solid line is without. This indicates a 300-350fpm lower climb rate with the tank.

Also please notice the curved line between 12500' and 15000'. That represents the point at which the pilot decreased rpm from 3000 (max) to 2600 (max continuous or max cruise) after the 5 minute mark complying with the time limit for those earlier engines. This reflects a substantial decrease in climb rate due to the lower HP for 2600rpm. The heavy dashed line at each 5000' interval is my estimate of climb after the five minute limit was increased to 15 minutes in mid '42. Just for fun.

Also notice the "SECRET" stamped in the upper right corner.

 

[P-39 Expert]

Perhaps not...but, then again, an aircraft getting caught on the ground has nothing to do with the performance of the aircraft and everything to do with the intelligence, early warning and C3 capabilities.

I just now noticed that your avatar photo is a Brewster Buffalo. Supposedly the Finns soundly whipped the Russians with that plane until they had to finally capitulate.

 

[pbehn]

Climb with tank is not shown on P-39N test, so I don't know for sure.

This shows 18 minutes to 25,000 ft
If your enemy is doing 180MPH they can go 54 miles in any direction in that time and you are hardly going any faster in terms of ground speed.

 

[Elmas]

Incredibly it was used as a training aircraft, I don't know what sort of training though.

Pilots who survived were certainly outstanding Pilots.

 

[drgondog]

Would several climb tests at military power be undertaken starting at different altitudes, to see the climb response when already in the air?

Yes - but normally initiated at incremental altitudes to determine initial ROC from level flight when WEP or MP applied.

 

[buffnut453]

Pilots who survived were certainly outstanding Pilots.

Or just plain lucky.

 

[pbehn]

Pilots who survived were certainly outstanding Pilots.

I was thinking of the many aspects of training, some like navigation and take off landing procedures are quite undemanding on the aircraft but I just don't see how you can train for combat with no risk of stall or spin.

 

[P-39 Expert]

Would several climb tests at military power be undertaken starting at different altitudes, to see the climb response when already in the air?

The test program for these planes was exhausting. Many flights at the different altitudes meticulously recorded by the pilots and the array of test equipment installed in the test plane. They didn't depend on the plane's instruments but used additional test equipment. Undoubtedly they did test climb at all altitudes and both at max power and max continuous power, but the graph shows a continuous climb from sea level up to the ceiling. Hope this helps.