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

[drgondog]

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

In late 1943 forward, both P-39s and P-40s were the steed of choice for Advanced Fighter Training prior to deployment offshore. There was a very narrow window in which the destination FG (US) were flying P39 or P-40/

My father's transition was P-40K at Sarasota, then 2.5 hours in P-51B at Goxhill in late May, 1944, then first combat mission (and victory credit) in P-51B on D-Day. He never flew the P-39.

 

[pbehn]

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.

Good heavens man! What do you think other testing organisations did, either companies or nations? Read the runes or studied tea leaves? The technology was very advanced all over the world, they just didn't produce lovely print outs from a bubble jet printer. As a former inspector who spent a life time looking at such things in a different field I can see where some "results" are written in when outside of the main area of interest. Here an example. From 0 to 12,400 ft rate of climb is exactly 2,720ft/min. I could possibly believe they would be similar, but not the same down to <1ft/min

Altitude
Ft. Speed MPH R.P.M. B.H.P. Rate ofclimb Ft/Min Time of climb Min.

-0000 -157 3000 1150 2720 0000
- 5,000 169 3000 1150 2720 1.84
-10,000 183 3000 1150 2720 3.68
*12,400 190 3000 1150 2720 4.56

 

[pbehn]

In late 1943 forward, both P-39s and P-40s were the steed of choice for Advanced Fighter Training prior to deployment offshore. There was a very narrow window in which the destination FG (US) were flying P39 or P-40/

My father's transition was P-40K at Sarasota, then 2.5 hours in P-51B at Goxhill in late May, 1944, then first combat mission (and victory credit) in P-51B on D-Day. He never flew the P-39.

Both my father and my uncle were bobbing about in boats on D-Day, I wonder if they saw him.

 

[P-39 Expert]

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?

No reduced fuel. If that P-39N had only 87 gallons then it would be only 33 gallons light x 6 pounds/gallon or 198# lighter. The N weighed 7650# loaded with 120 gallons internal, the cannon plus 2 .50 caliber machine guns and 4 .30 caliber wing guns and ammunition, and a 200# pilot with parachute. 7650# less half fuel (60 gal or 360#) resulting in an average weight for that flight of 7290# vs the listed weight of 7274#. Off by 16#. Same for the official performance tests (not different propeller tests etc) of the P-38, and P-47. Look it up.

Regarding facts, I am quoting the facts from the official government tests.

 

[P-39 Expert]

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.

At first glance those numbers look good to me. Note how your P-39D figures are EXACTLY the same as the P-39K graph in my post #773. The P-39K had about the same weight and the 8.8 geared engine as the D. And your P-39N numbers are EXACTLY the same as those I drew on the Hellcat climb chart in my post #717. That N could climb, eh?

The D did use 2600rpm after it reached 5 minutes, but was 3000rpm prior to that. You start your chart with 15000' and the shift occurred at 12500'.

The change in reduction gears, originally 1.8 in the D/F, then 2.0 in the K/L and 2.23 in the M/N/Q was to accommodate larger propellers. The larger propellers had to turn slower to keep the tips from going supersonic. Like you said, the newer hydraulic props were lighter than the Curtiss electric props. The only real difference in the M and the N was the different reduction gear but it sure made a big difference in climb, wouldn't you agree? So glad you posted this, facts are fun, no?

 

[DarrenW]

No reduced fuel. If that P-39N had only 87 gallons then it would be only 33 gallons light x 6 pounds/gallon or 198# lighter. The N weighed 7650# loaded with 120 gallons internal, the cannon plus 2 .50 caliber machine guns and 4 .30 caliber wing guns and ammunition, and a 200# pilot with parachute. 7650# less half fuel (60 gal or 360#) resulting in an average weight for that flight of 7290# vs the listed weight of 7274#. Off by 16#. Same for the official performance tests (not different propeller tests etc) of the P-38, and P-47. Look it up.

Regarding facts, I am quoting the facts from the official government tests.

Could you show us the "official government test" document which stipulated a normally loaded weight of 7,452lbs for a P-39N-1? And one not drawn in No. 2 pencil this time please....

 

[P-39 Expert]

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

Every pilots manual for an American WWII fighter had a warning not to snap roll or spin that airplane. The recovery methods are normal.

I don't think the spin chute was standard equipment, but was used on planes undergoing spin tests.

 

[DarrenW]

Every pilots manual for an American WWII fighter had a warning not to snap roll or spin that airplane.

That is patently false!

 

[pbehn]

Every pilots manual for an American WWII fighter had a warning not to snap roll or spin that airplane. The recovery methods are normal.

I don't think the spin chute was standard equipment, but was used on planes undergoing spin tests.

You have obviously made that up. The report recommends the pilots manual be modified as per their recommendations, so not normal. Are you saying that all US fighter pilots were forbidden from spinning and rolling a combat aircraft?

 

[Dimlee]

Great thread, I learned a lot about P-39. Many thanks to all contributors.
One can disagree with P-39 Expert's argumentation but he did bring a lot of interesting information to think over. And he is standing well so far - under the barrage.

 

[pbehn]

Great thread, I learned a lot about P-39. Many thanks to all contributors.
One can disagree with P-39 Expert's argumentation but he did bring a lot of interesting information to think over. And he is standing well so far - under the barrage.

I don't know if we have clearly established when the war started and ended yet.

 

[Shortround6]

Simple, the war started Dec 7th 1941 and the air war ended March of 1944

 

[P-39 Expert]

Could you show us the "official government test" document which stipulated a normally loaded weight of 7,452lbs for a P-39N-1? And one not drawn in No. 2 pencil this time please....

The P-39N pilots manual is not online, or at least I can't find it. I can find manuals for the K/L and the Q.

This chart is from the P-39K which was equipped the same. Empty weight 5658# including radios, oxygen equipment and fluids. The third column shows normal gross of 7648# including 120 gallons of fuel, oil, guns, ammo, armor plate and glass, and a 200# pilot with chute. First column is with a 75 gal drop tank, second column is with a bomb. Most all P-39s weight chart looked like this.

 

[P-39 Expert]

Great thread, I learned a lot about P-39. Many thanks to all contributors.
One can disagree with P-39 Expert's argumentation but he did bring a lot of interesting information to think over. And he is standing well so far - under the barrage.

Thank you sir. The fight continues. We will never surrender.

 

[Shortround6]

The only real difference in the M and the N was the different reduction gear but it sure made a big difference in climb, wouldn't you agree? So glad you posted this, facts are fun, no?

What troubles me about those figures is the P-39s apparent extreme sensitivity to power and and weight.
The P-39Q used the same engine and prop as the P-39N and yet the addition of 557lbs knocked 500fpm off the climb at 15,000ft, 430 fpm off at 20,000 and 370fpm off at 25,000.
Also note that the P-63, although it had about 1000lbs more weight, may have had around 1300hp at 15,000ft and 1200hp at 20,000ft.

Those P-39N figures are in an official document but I suspect you would be very hard pressed to get them in the field.

 

[pbehn]

The P-39N pilots manual is not online, or at least I can't find it. I can find manuals for the K/L and the Q.View attachment 487696

This chart is from the P-39K which was equipped the same. Empty weight 5658# including radios, oxygen equipment and fluids. The third column shows normal gross of 7648# including 120 gallons of fuel, oil, guns, ammo, armor plate and glass, and a 200# pilot with chute. First column is with a 75 gal drop tank, second column is with a bomb. Most all P-39s weight chart looked like this.

P-39 Flight Manual

on this very forum.

 

[P-39 Expert]

You have obviously made that up. The report recommends the pilots manual be modified as per their recommendations, so not normal. Are you saying that all US fighter pilots were forbidden from spinning and rolling a combat aircraft?[/QUO

Forbidden from INTENTIONALLY spinning per the manual. And a "snap roll" is different from a regular roll, look it up.

 

[DarrenW]

Thank you sir. The fight continues. We will never surrender.

What's this "we" stuff??? But I do agree it's been a real hoot discounting your facts one by one. Can you at least try to stick to one set of facts from now on, please???

 

[DarrenW]

Having limits on spins is not the same as being FORBIDDEN to perform one!

 

[drgondog]

Both my father and my uncle were bobbing about in boats on D-Day, I wonder if they saw him.

An interesting question - the shoot down occurred near Janville as 15 Stukas were caught sneaking in at dusk 100' off the deck.

The Area Patrol was between 10 and 15K and following RTB, dropped to the deck for strafing when the 357FS called the Ju-87s rallied the two squadrons in for the shoot. Went out in a direct line from Janville so nowhere near Normandy.

His first combat mission was at 0251 to 0851 on an Area Patrol just east of the Beachhead - dropping down to shoot stuff up behind German lines near Caen... so this one possible