Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained) (2 Viewers)

[Snautzer01]

Picture of a dead thread creeping back to life.

 

[P-39 Expert]

If they had axed the P-39 and ordered the XP-51 right away, could Bell have also built more P-40's for Curtis? Not that it didn't have it's own quirks and flaws, but it was still a far better aircraft than the P-39 especially when flown with significant overboost.

No way the P-40 was superior to the P-39 in speed climb ceiling or range.

 

[buffnut453]

No way the P-40 was superior to the P-39 in speed climb ceiling or range.

P-40E Range: 716 mi (1,152 km, 622 nmi) at 70% power
P-39Q Range: 525 mi (845 km, 456 nmi) on internal fuel

Is this some kind of new math where 525 is actually greater than 716?

Of course the P-39's range can be increased by the addition of the external drop tank...but that reduces its speed to below that of the P-40.

 

[P-39 Expert]

The "early 2 stage Spitfire MkIX" was a 1942 aircraft. Only 4 squadrons active with the Mk IX before Sept '42, basically test batches. Real production of the Mk IX was in 1943.

By 1943 the engines had improved.

Do you think the P-39N is actually a match for the P-51A? The P-51A being faster and longer ranged. Charts for the P-51A and P-39Q (no wing guns) below. P-51 is about 10mph faster even though with a sanded and polished finish. Climb is almost identical even though the P-51 weight was reduced to 8000lbs (from 8600) and carried only 105gal fuel (normally 180). Hard to believe they climbed at the same rate when the P-39 was 400lbs lighter with the same engine. P-39N tests showed an additional 600fpm climb. Performance of these two planes, even with the P-51 finish being sanded and weighing 600lbs less than normal, was about even. I would consider them a match.

What about the Spitfire XII? Sure only 100 made, but top speed about the same as the P-39N, best performance in a similar altitude band, but better climb rate than the P-39N. You said it, only 100 made. Griffon engine was 30% larger than the Allison and had a two stage supercharger. Not really any faster and didn't climb as well as a P-39N.

Typhoon Ib? Faster, with more firepower. And range. According to wwiiaircraftperformance.org the Typhoon 1b had about the same speed at 20000ft but a lot slower below. Climb was 2000fpm at 20000ft when the P-39N would climb at 2650fpm at 20000ft. Not a bad plane, about like a 1943 Corsair, Hellcat or FW190.

Fw190A (not sure which subvariant was best by 1943)? By your own reckoning, the P-39N was no match for the Spitfire IX, the Fw190A was, or was close. Surely that would mean the Fw 190A outmatched the P-39N? You can compare a 190 with a Spitfire V but not a Mk IX. Mk IX would climb away from a 190 at any altitude, would climb almost THREE times as fast at 26000ft. No comparison, especially when the 190 couldn't use full power through most of the war. Against the P-39N the 190 was about the same speed but climbed 600fpm slower at 20000ft. And a lot less maneuverable than the P-39.

 

[tomo pauk]

The 1942 P-39 (D/F/K/L) was way too heavy when compared with contemporary fighters power/weight ratio. Delete the unnecessary/redundant wing guns, nose armor plate and IFF radio and those P-39s weigh 7150lbs.

Still does not do things required by USAAF Pacific (the area USAAF was mostly fighting in 1942). In best part of 1942, it required the -83 engine (so it can compete above 15000 ft) and at least 50% more fuel (so it can cover the area better).
It wasn't so.

No plane will meet these specs until the Merlin P-51 in 1944. A 1943 P-39N was very competitive with any other 1943 fighter. Except the early two stage Spitfire MkIX.

P-47 has certainly a potential to do 500 mile escort with wing tanks in 1943. P-38 - ditto (and a bit longer). P-39 can do how much of the escort job at 25000 @ 300 mph TAS? 250-300 miles?

I'm wrong that a 20% larger engine should make more power?
Yes, with 20% less displacement.

You've answered your own question there.

Never said any P-39 had the two stage engine (except the P-39E), just said it would fit with minor modifications. The engine was in production in April '43 but the first P-63 airframe wasn't ready until October '43. Put the engine in the P-39 until the P-63 was ready.

P-39E required major modifications of central and rear fuselage in order to the cooling systems and the 2-stage engine to fit inside. Once all of that was done, the P-39E was found to have dangerous spin characteristics - no wonder with the extra weight added aft the CoG.

 

[Schweik]

The P-40 used a similar engine that was rated mostly at about 1,325 hp. Some had engines of 1,425 HP or so. Two variants of the P-40, the P-40F and P-40L, had Packard-Merlin V-1650 engine, but the Merlins so used were single-stage engines and the resulting P-40s performed almost the same as with the Allison engines. The Merlin-powered units were very slightly faster and had very slightly better altitude performance, but not enough to make much of a difference. They were still low-altitude fighters. You can tell the Merlin units because they airscoop on top of the nose is missing.

Good post overall, but this part is incorrect and it's one of those tropes that just lingers forever.

The Merlin engine did make a big difference, big enough that the Merlin engined variants were almost the only type of P-40 used by the five American fighter groups that flew P-40s in the Mediterranean Theater (North Africa and then Italy). The Merlin engine, being single-stage (but two speed), didn't do for the P-40 what the (2 stage) Merlin did for the P-51, and it didn't turn it into a high altitude fighter, but it did increase the combat altitude considerably and that was the main reason it was so much in demand.

P-40 variants in the MTO included:

P-40 B/C (Allison Engined used only by the British and Commonwealth Air Forces as Tomahawk IIA and IIB)
P-40 D/E (Allison V-1710-39, used only by the British and Commonwealth Air Forces as Kittyhawk I and IA)
P-40 F (Merlin 28 / V-1650-1 engined, used by 5 US fighter groups, 2 British squadrons as Kittyhawk II, and 1 Free French)
P-40 L (Merlin 28 / V-1650-1 engined, used by 5 US fighter groups, 2 British squadrons, as Kittyhawk IIa, and 1 Free French)
P-40 K (Allison V-1710-73, used briefly by one US FG - 57th FG - during a shortage of Merlin engines, used by British and Commonwealth units as Kittyhawk III)
P-40 M (Allison V-1710 -81 used by British and Commonwealth forces as Kittyhawk III, mainly used as a fighter bomber)
P-40 N (Allison V-1710 -115 and others, used by British and Commonwealth forces as Kittyhawk IV, almost exclusively used as a fighter-bomber)

All variants through the K were used in the air superiority role, but only the F/L could be called successful in terms of win / loss ratios. The P-40B/C "Tomahawk" had an effective performance ceiling of about 14,000 ft and could fight up to about 16-17,000'. The E and K had an even lower effective performance ceiling of about 12,000' . Above about 15,000 they were very sluggish. The K was considered one of the best Allison variants however because the allowed boost settings had been increased, and at WEP setting it had 1,550 hp available, but only down below 3,000 ft. The M and N varied but most had a higher-tuned engine with an effective ceiling of around 17-18,000', but with lower maximum boost allowed down low.

The critical altitude for the (Packard Merlin) V-1650 powered P-40F and L was just under 18,000 ft, and they were able to operate effectively up to a bit over 21,000. This wasn't much lower than the effective performance altitude for the Spitfire Mk V, and it made a significant difference. At altitude it was about 30 mph faster than a P-40E and (depending on the loadout) had a much improved rate of climb. They were able to operate 6-8,000' higher than the Allison P-40 models which meant being pounced less often and with less ease by Bf 109s and MC 202s.

It's worth noting that the P-40N was widely used by the USAAF in the Air Superiority role in the Pacific and China / India / Burma Theaters against Japanese fighters, but was not considered viable for operations against the Germans, whereas the Merlin powered F and L were.

The P-39 was used briefly by US forces in the Med, but after some disastrous engagements was relegated to 'Coastal Patrol' duties, for which it was ill suited due to short range. After a gradual familiarization process and some improved models with more powerful engines arrived in Theater, it was put into use as a fighter bomber in Italy with moderate success.

There were 18 US pilots who made Ace while flying P-40s in the MTO, and at least 35 British and Commonwealth pilots, but so far as I've been able to determine only one US P-39 Ace in the entire war, and that was in the Pacific.

US P-40 pilots claims: 592 victories in the MTO, 660.5 in the PTO, and 973 in China for a total of 2225.5
US P-39 pilots claims: 2.5 victories in the ETO, 25 in the MTO, 288 in the Pacific, 5 in China, for a total of 320.5

The Russians were able to do something with the P-39 that neither the US nor the British nor the other Western Allies we saddled with them (some high scoring Italian and French aces were killed in accidents in these planes) were able to do.

 

[Peter Gunn]

On doctors advice, I am no longer allowed to install or remove fuel tanks, armour or weapons, at any time.

My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.

 

[pbehn]

My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.

I got the same but from my anger management consultant, and mental health awareness self help group.

 

[P-39 Expert]

P-40E Range: 716 mi (1,152 km, 622 nmi) at 70% power
P-39Q Range: 525 mi (845 km, 456 nmi) on internal fuel

Is this some kind of new math where 525 is actually greater than 716?

Of course the P-39's range can be increased by the addition of the external drop tank...but that reduces its speed to below that of the P-40.

According the the pilot's handbooks for P-40E and P-39K/L (same engine power above 12000ft):

Clean:
P-40 12000ft 148gal less 28gal warmup&climb = 120net gallons divided by 41gph = 2.9hours x 235mph = 681mi.
P-39 12000ft 120gal less 20gal warmup&climb = 100net gallons divided by 33gph = 3.0hours x 241mph = 723mi. P-39 cruised faster than P-40 at a lower power setting.

We can do this at any altitude with any external tank. P-39 was faster, climbed faster and cruised farther then P-40.

 

[Thumpalumpacus]

My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.

Huffing the dirt from a groundhog discussion impairs respiration, I'm told.

 

[Milosh]

Flight Operation Instruction Chart

P39FOIC.pdf (zenoswarbirdvideos.com)
P-40FOIC.pdf (zenoswarbirdvideos.com)

 

[P-39 Expert]

Still does not do things required by USAAF Pacific (the area USAAF was mostly fighting in 1942). In best part of 1942, it required the -83 engine (so it can compete above 15000 ft) and at least 50% more fuel (so it can cover the area better).
It wasn't so. In 1942 the AAF was in a defensive position. Only thing the P-39 had trouble doing was intercepting IJN bombers at 18000-22000ft headed for Moresby. Could intercept them about half the time. At 7150lbs it could intercept them all the time. Otherwise the escort of medium bombers and transports was no problem.



P-47 has certainly a potential to do 500 mile escort with wing tanks in 1943. P-38 - ditto (and a bit longer). P-39 can do how much of the escort job at 25000 @ 300 mph TAS? 250-300 miles? P-47 could only escort about 350mi radius in 1943 and then only after drop tanks introduced in August. I have a range chart but can't seem to make it attach.



You've answered your own question there. A larger engine will make more power.



P-39E required major modifications of central and rear fuselage in order to the cooling systems and the 2-stage engine to fit inside. Once all of that was done, the P-39E was found to have dangerous spin characteristics - no wonder with the extra weight added aft the CoG. I'm not talking about an 8900lb P-39E. I'm saying put the -93 engine in a standard P-39, offset the weight of the auxiliary stage with a larger four blade propeller. The -03 engine would fit into a standard P-39, I've shown the drawings on here many times. Whole thing would have weighed about 7900lbs.

 

[P-39 Expert]

Flight Operation Instruction Chart

P39FOIC.pdf (zenoswarbirdvideos.com)
P-40FOIC.pdf (zenoswarbirdvideos.com)

I used that same P-40D/E chart for my calculations.
That P-39 chart is for a P-39Q with 86 gallons internal and a different engine. I used a P-39K/L chart with a more comparable engine and the normal 120gal internal fuel.

 

[Milosh]

Produce the chart.

 

[drgondog]

According the the pilot's handbooks for P-40E and P-39K/L (same engine power above 12000ft):

Clean:
P-40 12000ft 148gal less 28gal warmup&climb = 120net gallons divided by 41gph = 2.9hours x 235mph = 681mi.
P-39 12000ft 120gal less 20gal warmup&climb = 100net gallons divided by 33gph = 3.0hours x 241mph = 723mi. P-39 cruised faster than P-40 at a lower power setting.

We can do this at any altitude with any external tank. P-39 was faster, climbed faster and cruised farther then P-40.

Nope - P-39 Faster (under 18K vs P-40F, then P-40F faster by 20mph), better acceleration (under 18K vs P-40F/K) and better climber (except vs P-40F/K from 18K ), much slower roll rate than P-40 (any model), less terminal dive speed, shorter range, less external load, less practical armament than P-40E and Subs, for most strafing and all air to air due to the issues with M-4 37mm cannon. Nobody in USAAF, RAF, Commonwealth, French and Italians were crying for more P-39s.

Don't depend on your calculations -use USAAF Published Tables as reproduced on page 599 of AOHT, Table 100. Boundary conditions are 10 minutes of fuel for warm up, taxi, takeoff and landing. It allows for fuel used to climb to 10,000 feet, cruise and 10% of net ideal range for other factors - at more economical power speed. Below table values are for pure straight line range from take off to reserve point..

Pilot Handbook values were contractor developed and the USAAF tables were developed from flight testing - and averaged across multiple ships same type.

P-39D/F/K (VERY best P-39 range performance w/120 gal and TO weight of 7650) = 600 mi. The P-39N w/87gal TO wt of 7550 =350 mi; =550mi for 120gal.
The P-39N is probably the best comparison as it was most widely produced
P-40E (149gal and TO weight of 8700) = 650mi
P-40F/K (157gal Merlin 1650-1, TO weight of 8800) = 700mi

 

[wuzak]

Only 4 squadrons active with the Mk IX before Sept '42, basically test batches. Real production of the Mk IX was in 1943.

You mean the 4 squadrons hat took part in the Dieppe landings?

I doubt they were "test batches". Just early production machines. And production started months earlier and continued.

You said it, only 100 made. Griffon engine was 30% larger than the Allison and had a two stage supercharger. Not really any faster and didn't climb as well as a P-39N.

The Spitfire XII was powered by either a Griffon II, Griffon III or Griffon VI, all single stage, 2 speed models. With the Griffon VI the maximum climb rate was very nearly 5,000fpm.

The reason only 100 were made was because the Griffon was needed for the Firefly, and that 2 stage Griffon Spitfire was being developed.

The 2 stage Griffon powered Spitfire was the XIV, which started production in 1943, but did not see service until 1944.

 

[DerAdlerIstGelandet]

Nope - P-39 Faster (under 18K vs P-40F, then P-40F faster by 20mph), better acceleration (under 18K vs P-40F/K) and better climber (except vs P-40F/K from 18K ), much slower roll rate than P-40 (any model), less terminal dive speed, shorter range, less external load, less practical armament than P-40E and Subs, for most strafing and all air to air due to the issues with M-4 37mm cannon. Nobody in USAAF, RAF, Commonwealth, French and Italians were crying for more P-39s.

Don't depend on your calculations -use USAAF Published Tables as reproduced on page 599 of AOHT, Table 100. Boundary conditions are 10 minutes of fuel for warm up, taxi, takeoff and landing. It allows for fuel used to climb to 10,000 feet, cruise and 10% of net ideal range for other factors - at more economical power speed. Below table values are for pure straight line range from take off to reserve point..

Pilot Handbook values were contractor developed and the USAAF tables were developed from flight testing - and averaged across multiple ships same type.

P-39D/F/K (VERY best P-39 range performance w/120 gal and TO weight of 7650) = 600 mi. The P-39N w/87gal TO wt of 7550 =350 mi; =550mi for 120gal.
The P-39N is probably the best comparison as it was most widely produced
P-40E (149gal and TO weight of 8700) = 650mi
P-40F/K (157gal Merlin 1650-1, TO weight of 8800) = 700mi

It's futile my friend. I would not waste my time. He's right, you're wrong...

 

[DerAdlerIstGelandet]

I have moved all the P-39 vs P-40 talk into this thread about the P-39 vs. the P-40.

P-39 Expert stop hijacking threads and turning them into P-39 threads. It's getting really tiring...

 

[pbehn]

You mean the 4 squadrons hat took part in the Dieppe landings?

According to wiki there were 6 squadrons of Spitfire Mk IXs at Dieppe, 4 RAF and 2 RCAF.

"Six squadrons (four British, two Canadian) flew the Spitfire Mk IX, the only British fighter equal to the Fw 190, on its operational debut at Dieppe.[46] Copp, Terry. "The Air over Dieppe." Legion, June 1996, p. 8" Dieppe Raid - Wikipedia

 

[buffnut453]

I have moved all the P-39 vs P-40 talk into this thread about the P-39 vs. the P-40.

P-39 Expert stop hijacking threads and turning them into P-39 threads. It's getting really tiring...

Or, better yet, find another topic to talk about. Any topic...we're not picky.