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

[tomo pauk]

Of this I was aware.

The Merlin doesn't have to be the 1650-3. The V-1650-1 could give a useful altitude performance gain without much weight penalty, and it shouldn't require the massive increase in cooling capacity for the -3.

Though Packard didn't make them, I wonder how a Merlin 45 would have gone in the P-39. Obviously low down performance would suffer, but there should be some gain at higher altitudes (the 45 having a higher FTH than the Allison).

Actually not by that much once the later Allisons with 9.60 gears showed up. Critical height the Merlin 45 may be 3-4,000ft higher than a late model P-39 which would be a help but not solve the problem. The Late Allisons sort of split the difference between an early Allison and the Merlin 45.

A big problem is the weight, A P-39D clean is about 1000lbs heavier than a Spit V clean or almost 15%. Put together with the smaller wing and the wing loading was about 30% higher. At altitude the P-39 has to fly faster just to keep from stalling leaving that much less power for climb and maneuver.

Then you have a take-off problem. Early P-39s had 1150hp for take-off, late model Ds, Ks and Ls had 1325hp for take-off and the late versions had 1200hp for take-off. Merlin 45 had 1230hp for take-off at 12 lb boost. While the Allison was rated for 5 minutes CLIMBING at take-off or Military Power the Merlin was not so rated, what they did in the squadrons I don't know. We do know that Allisons tolerated over-boost abuse fairly well at low altitudes.

Indeed, I was thinking about V-1650-1 (note to self - next time be direct, instead of being cryptic).
That engine was able to outperform single stage V-1710 at every altitude, and it was available earlier than the '9.60 V-1710s' show up. Installation of that engine would've dictated also the relocation of (now longer) engine intake into a place not hampered from having the canopy ahead itself, should help to better use of ram effect.
The main problem to get V-1650-1 in P-39 would've been the low availability; also, IIRC the reduction gear was integral with crankcase - not compatible with P-39 power-plant installation.

BTW, the grpah kindly posted by krieghund neatly describes the single-stage V-1710 as an 'altitude rated engine'

 

[krieghund]

Well climb and speed are only a few of the factors involved in determining maneuverability. It would appear at face value that the P-39 has the advantage but I would suspect the F4F is the more nimble due to a lower wing loading and able to easily out turn the P-39. The P-39 probably bleeds energy faster than the F4F as well. Remember later in the war the USN used the F4F (FM-2) to simulate the Zero in dissimilar aerial combat training. The P-39 would have to employ AVG tactics against the F4F.

 

[krieghund]

Here's a comparison of the engine charts from the flight manuals. The military power recommended duration on the V1710 is 15 minutes and the V1650 is 5 minutes. A clear advantage of the V1650 in military is an increase in critical altitude by over 6000 feet. Of course the V1710 is the without ram. With ram it approaches 14,900 feet

 

[tomo pauk]

The table for the V-1650-1 lists the critical altitudes in the wrong column, under 'with ram', instead under 'no ram'.

 

[wuzak]

The main problem to get V-1650-1 in P-39 would've been the low availability; also, IIRC the reduction gear was integral with crankcase - not compatible with P-39 power-plant installation.

I don't think that the reduction gear was a big issue, tbh. Just needs a new casing with bearing and output shaft, as Rolls-Royce did with the Griffon for the Flying Test Bed (FTB). They could also use a torque tube, as was done in the FTB.

The main issues with the Merlin was the updraft carburettor. A downdraft carby would make fitting easier, but not sure how easy it was to convert.

The V-1650-1 should be a little shorter than the V-1710.

http://www.airpages.ru/draw/merlin25.gif

 

[krieghund]

The table for the V-1650-1 lists the critical altitudes in the wrong column, under 'with ram', instead under 'no ram'.

Would you have a source that has the correct information?

 

[varsity078740]

Some US pilots were able to engage the Japanese at altitudes where the P-39 was able to put up a fight. "Buzz" Wagner was one of the first US aces and scrored kills in both P-40 and P-39. He led several low level raids that were quite successful before being sent back to the US with 8 credits. He was later killed in a P-40 crash stateside.

Pittsburgh Post-Gazette - Google News Archive Search

There's more than a little doubt about the 3 kills attributed to Wagner on that mission.

Duane

 

[pinsog]

There's more than a little doubt about the 3 kills attributed to Wagner on that mission.

Duane

Do you have any details? Could you please explain what the other side of the story is?

 

[varsity078740]

Do you have any details? Could you please explain what the other side of the story is?

Officially he's credited with 3 Zeros although contemporary records vary from one to three. None of the narratives from other pilots mention Zeros shot down by Wagner. A total of 4 claims were made for the mission. Until recently, available Japanese records shed no light on the mission, but recent research by Michael Claringbould shows one loss, FPO2c Izumi Hideo. He may have been shot down by George Greene who claimed hits on a Zero that he thought fell to the water.

Duane

 

[FLYBOYJ]

There's more than a little doubt about the 3 kills attributed to Wagner on that mission.

Duane

Bottom line, Wagner and his pilots successfully brought the fight to the Japanese and did show the P-39 could at least hold its own uncer the right circumstances.

We could also re-write history and take 3 credits away from one of the first US Aces...

 

[tomo pauk]

Would you have a source that has the correct information?

The part of the document encompassing the US airplane engines (open the picture in separate tab for hi-res):

Whole document:

http://www.enginehistory.org/ModDesig/SecI.pdf

 

[varsity078740]

Bottom line, Wagner and his pilots successfully brought the fight to the Japanese and did show the P-39 could at least hold its own uncer the right circumstances.

We could also re-write history and take 3 credits away from one of the first US Aces...

I don't think that history needs to be rewritten and I'm not saying for certain that he didn't shoot down the 3 Zeros. But it remains a controversial topic as noted in the 8th Fighter Groups history Attack and Conquer. Nevertheless The Air Force
and the American Aces Association both credit him with 8 victories which includes the 3 from the Lae Mission. But, it's no secret that alot of the stories that came out of the Pacific during the first 6 months of the war were pure propaganda. Witness the variety of stories about Colin Kelly. When the legend becomes fact, print the legend. As far as the merits of the P-39 vs. the Zero goes, Wagner's written report on it after the Lae mission is very informative.

Duane

 

[FLYBOYJ]

I don't think that history needs to be rewritten and I'm not saying for certain that he didn't shoot down the 3 Zeros. But it remains a controversial topic as noted in the 8th Fighter Groups history Attack and Conquer. Nevertheless The Air Force
and the American Aces Association both credit him with 8 victories which includes the 3 from the Lae Mission. But, it's no secret that alot of the stories that came out of the Pacific during the first 6 months of the war were pure propaganda. Witness the variety of stories about Colin Kelly. When the legend becomes fact, print the legend. As far as the merits of the P-39 vs. the Zero goes, Wagner's written report on it after the Lae mission is very informative.

Duane

And that mission also gave a big boost to the 8FG, it really showed that the USAAF WAS capable of taking on the Japanese even with P-39s and P-40s.

 

[pinsog]

Down on the deck, one on one with a Zero, what would you guys want to be in, a P39, an F4F or a P40? Personally, I would take the P39 because it is alot faster and has a very good climb rate down low. Of course, hind sight 20/20, I would also want all the wing guns removed to dump a few hundred pounds of extra weight and I would want the 20mm cannon and not the 37mm cannon.

 

[Conslaw]

Pinsog, I have noticed the same thing - the charts show the P-39 as faster than the F4F to 24,000 feet, and if we overlaid a A6M-2 chart, the P-39 would likely have a similar paper advantage over the Zero. So why did the P-39 have the reputation of being such a dog at much lower altitudes, sometimes 12,000 to 15,000 feet? I can understand that the Guadalcanal P-400s didn't have oxygen. That's a good excuse, but the New Guinea P-39s had the reputation of being dogs both to the American and the Japanese pilots, and they were U.S. spec.

 

[Glider]

Down on the deck, one on one with a Zero, what would you guys want to be in, a P39, an F4F or a P40? Personally, I would take the P39 because it is alot faster and has a very good climb rate down low. Of course, hind sight 20/20, I would also want all the wing guns removed to dump a few hundred pounds of extra weight and I would want the 20mm cannon and not the 37mm cannon.

Personally I would take the Zero

 

[varsity078740]

Pinsog, I have noticed the same thing - the charts show the P-39 as faster than the F4F to 24,000 feet, and if we overlaid a A6M-2 chart, the P-39 would likely have a similar paper advantage over the Zero. So why did the P-39 have the reputation of being such a dog at much lower altitudes, sometimes 12,000 to 15,000 feet? I can understand that the Guadalcanal P-400s didn't have oxygen. That's a good excuse, but the New Guinea P-39s had the reputation of being dogs both to the American and the Japanese pilots, and they were U.S. spec.

The P-39 was not a "dog" at 12,000 feet but at 24,000 it needed full throttle to keep from stalling. In the early part of the New Guinea campaign, the P-39 was used as an interceptor against bombers with escorts coming over the target at altitudes over 20,000. They never were able to attain an altitude advantage during attempted intercepts and were constantly bounced by escorts coming down on them from higher altitudes. The 8th Pursuit(fighter)Group was decimated. At Guadalcanal lack of oxygen for P-400s was a mute point. They couldn't get to the same height as the F4Fs with or without oxygen.

Duane

 

[Shortround6]

The performance charts are all corrected to stand air pressure and sometimes standard temperature. Temperature is usually 59 or 60 degrees F or 15 degrees C. BUT NOT ALWAYS.

See:

Please note that for THIS chart take-off distance and time for climb are figured for 0 degrees C or 32 degrees F and need 15% added to them just to bring them TO STANDARD.

Now adjust for 90-100 degree tropical heat on some days and the climb rate IN THEATER can take a real beating compared to the test results at factory or test center. And no, the air temp at 20,000ft is not the same world over.

 

[Conslaw]

Wouldn't the performance of all aircraft be negatively affected by the high density-altitudes caused by the high temperatures? Why the p-39 more than the P-40? the navy got loaded TBDs over the Owen Stanleys for Pete's sake. When WWII pilots refer to altitude, are they generally talking about density altitude, or actual distance over sea level?

 

[Njaco]

isn't this for a P-47?