P-39 vs P-40

Shortround6 · Jan 6, 2019

Schweik said:
Not debating it but where do you get 1410 hp @ 9,500 ft for the -81? And where do you get the altitudes for WEP ratings for the -39 and -73? My books just say 'Sea Level' for WEP. I'm always looking for new and more accurate sources.

I am getting most of the information from "Vees for Victory" by Danial Whitney. A history of the Allison engine

Schweik said:
Wasn't 60" approved for later model P-40E / V-1710-39 as well as for the -73?

This one is subject to question, approved by who? sometimes the engine company and the Military did not agree. Sometimes the the engine company wanted to use higher ratings and sometimes the engine company didn't really want to approve WEP ratings ( Try and find WEP ratings in P & W company literature for example).
As far as the -39 goes, remember that the change to the nitrided crankshaft came part way through the production run, they did not change the model number of the engine.
Any -39 engine could make the level of power at 60in of MAP, the question was for how long? or how many times.

Schweik said:
Is it true what some people are saying that Merlin XX had weak power down low?

That really depends on when. As in 1940 when first issued and the boost was limited to 9lbs (48in) or when it was cleared to use 12lbs boost or when it went to 14lbs in low gear and 16lbs in high gear. 14lbs is 58in (or close) and the Merlin XX (in British service) was rated at 1485hp at 6000ft no RAM, it may not have been cleared for 1600hp or so at sea level but 1485hp at 6000ft doesn't look too shabby to me.

Schweik · Jan 6, 2019

Agreed, obviously talking about 1942 here

CORSNING · Jan 6, 2019

April 1943 90 P-39Ns are supplied to the French in North Africa. June 1943
the 18th FG becomes operational with P-39Ns at Guadalcanal.

1 September 1943 P-40N-5s become operational at Baker Island.
I'm still working on the P-40N-1.

September 1943 the P-51A becomes operational with the 23 rd. FG.

Schweik · Jan 6, 2019

CORSNING said:
April 1943 90 P-39Ns are supplied to the French in North Africa. June 1943
the 18th FG becomes operational with P-39Ns at Guadalcanal.

1 September 1943 P-40N-5s become operational at Baker Island.
I'm still working on the P-40N-1.

September 1943 the P-51A becomes operational with the 23 rd. FG.

Okay fair enough consider me schooled

tomo pauk · Jan 6, 2019

Schweik said:
Not debating it but where do you get 1410 hp @ 9,500 ft for the -81? And where do you get the altitudes for WEP ratings for the -39 and -73? My books just say 'Sea Level' for WEP. I'm always looking for new and more accurate sources.
...
Is it true what some people are saying that Merlin XX had weak power down low?

Don't believe those people - factory approved 1300 HP+ by late 1940, 1470 HP by late 1942: link1 link2

As for the V-1710-81:

Wildcat · Jan 7, 2019

CORSNING said:
The first long fuselage P-40Ks (-10) were delivered in October
1944.

Hi Corsning. I have 77 sqn RAAF operational with P-40K-10's on 22 February 1943 out of Gurney airstrip, New Guinea.

varsity07840 · Jan 7, 2019

Schweik said:
The P-51A had some kind of problem with the ailerons which was fixed on the P-51B/C and later. I think later versions had a very good roll rate.

This is interesting though I think it would make more sense to compare P-40K or L to the others as they were contemporaries. P-40N wasn't used that much in combat (by the RAF as a bomber in Italy, by the RAAF a bit in the Pacific and by the USAAF in Burma and India.

By contrast the P-40K was widely used from Russia to Tunisia to the Solomon Islands and China, and the L, along with the F, were the main variants used by the USAAF against the Germans.

But it is harder to find those numbers.

If you are going to use P-40N note that at 57" / WEP the climb are a little lower initially but hold up better to a little bit higher altitude

http://www.wwiiaircraftperformance.org/P-40/A29-412-climb-WEP.jpg

it starts from 3100 fpm and peaks at 3380 at 6800 ft.

The P-40N was widely used by the 5th AF in the Pacific and still equipped the 110th TRS during the invasion of the Philippines in Nov. 1944

Schweik · Jan 7, 2019

Interesting, but were they in combat much? Were they still racking up victories in 1944? My understanding for the Pacific (as distinct from the CBI) was that most US P-40 units were kind of out of the game except for CAP (patrol over airfields etc.) because they longer had the range to reach Japanese targets. I know Australian Kittyhawk units were still getting some victories through 1944, I believe New Zealanders had already switched to Corsairs in 1943 (though they were no longer encountering many enemy planes anyway and I don't think made any victory claims with them).

CORSNING · Jan 7, 2019

Wildcat said:
Hi Corsning. I have 77 sqn RAAF operational with P-40K-10's on 22 February 1943 out of Gurney airstrip, New Guinea.

Wildcat,
Great information, what is your source ?

Guys,
I am extremely busy with work, family and animals at this time. I have been able to put
together horse power ratings for the Allison V-1710-81, 83, 85 that were standard in
1942 and 1943. I hope to post this information in the next two days.

All the best and may God bless all, Jeff

CORSNING · Jan 7, 2019

Schweik said:
Interesting, but were they in combat much? Were they still racking up victories in 1944? My understanding for the Pacific (as distinct from the CBI) was that most US P-40 units were kind of out of the game except for CAP (patrol over airfields etc.) because they longer had the range to reach Japanese targets. I know Australian Kittyhawk units were still getting some victories through 1944, I believe New Zealanders had already switched to Corsairs in 1943 (though they were no longer encountering many enemy planes anyway and I don't think made any victory claims with them).

No time to elaborate (see previous post)

AHT:
January 1, 1944- "In the war against Japan the Army is using 630 P-40s out of a total of 1765 fighters."

Wildcat · Jan 8, 2019

CORSNING said:
Wildcat,
Great information, what is your source ?

Guys,
I am extremely busy with work, family and animals at this time. I have been able to put
together horse power ratings for the Allison V-1710-81, 83, 85 that were standard in
1942 and 1943. I hope to post this information in the next two days.

All the best and may God bless all, Jeff

Hi Jeff, I got that info straight from the squadron Operations record book.

CORSNING · Jan 8, 2019

Thank you Wildcat. If you do not mind, I will add that to the P-40 timeline
I have put together for posting at a later date.

Wildcat · Jan 8, 2019

Your welcome, glad it was of use. If you need any other dates for RAAF P-40 usage I'll be happy to look for you.

CORSNING · Jan 8, 2019

Horse Power of the Allison V-1710-81 & -85 per the USAAF 1942/1943.

All the following information can be viewed on
WWII Aircraft Performance

All my research is due to the spark to get started by the information posted
by Mr. Mike Williams and Mr. Neil Stirling. I would also like to thank Mr.
Henning Ruch for renewed support and Mr. Greg Pascal for the confidence
and support to start posting. Thank you all.

All the following information comes from the War Department, Army Air
Corps./Forces, Materiel Center/Division/Command....one or the other.
All reports were addressed; Wright Field, Dayton, Ohio.

All figures for horsepower are at a manifold boosting of 57"Hg.

P-39N-1 42-4400 (V-1710-85/E-19)
From Report Serial No. FS-M-19-1510-A dated November 24, 1942.
1355 hp./S.L.
1390 hp./7,500 ft.
Graph accompanying Report serial number FS-M-19-1487-A
1295 hp./S.L.
1420 hp./9,700 ft.
"Horsepower obtained from power curve V-1710-83 and -85 dated September
19, 1942 (2,23:1 propeller gear ratio; 9.6:1 blower gear)."

P-40N-1 42-9987 (V-1710-81/F20R)
From Report Serial No. FS-M-19-1535-A dated January 30, 1943.
Speed trials:
1415 hp./2,960 ft.
1480 hp./10,550 ft. Full throttle height.
Climb trials:
1400 hp./S.L.
1450 hp./5,000 ft.
1480 hp./8,000 ft. Critical altitude.
Graph from P-39N-1 listed above shows the following results:
1385 hp./S.L.
1480 hp./10,550 ft.
"Horsepower obtained from power curve V-1710-81, 83 & 85 dated October
28, 29, 1942 (2:1 propeller gear ratio; 9.6:1 blower gear)."

P-51A 43-6007 (V-1710-81/F20R)
From Report Serial No. PHQ-M-19-1576-A dated April 2, 1943.
1480 hp./5,000 ft.
1480 hp./10,400 ft.
Those figures match perfectly with the accompanying graph referencing
FS-M-19-1576-A
1480 hp./S.L.
1480 hp./10,400 ft. Full throttle height.
"Horsepower obtained from power curve V1710-91, 83 & 85 dated October
28, 29, 1942 (2:1 propeller gear ratio; 9.6: 1 blower gear)."

Good night guys hope to hear from all tomorrow, Jeff

CORSNING · Jan 9, 2019

Wildcat said:
Your welcome, glad it was of use. If you need any other dates for RAAF P-40 usage I'll be happy to look for you.

In the WW2 fighter timelines I have put together I am modifying them to include delivery
dates, first date operational and first combat date (if known). Any information you may
have on any version of any of the fighter's first operational status with the RAAF would
be greatly appreciated.
No pressure mate, I greatly appreciate the information you have already given.

CORSNING · Jan 9, 2019

Thank you all for a great discussion. I am thankful because these discussions
force me to dig through my files and others more deeply, a great learning
process.
I was recently forced to study these aircraft more closely and stumbled upon
an interesting note that I apparently had not caught before. ...The P-40N-1
was tested with external gas tank shackles in place. P-40F 41-13635 in report
Ser. No. FS-M-19-1578-A dated April 3, 1943 showed an increase of speed at
full throttle height of 8.5 mph. Speed was increased from 365.5 mph to 374 mph
at 18,100 ft. by the removal of the shackles (belly sway braces). This all mean the
speed of the P-40N-1 from sea level to FTH should be increased about 8 mph.
That would put the true war emergency maximum speeds of the P-40N-1 in clean
condition around 340 mph./S.L. and 386 mph./10,550 ft.
Just food for thought.

P-39N-1 @ 7,301 lb. .[ P-40N-1 @ 7,413 lb. ]. P-51A @ 8,000 lb.

Altitude / Speed / Climb
Meters / MPH / FPM
S.L........344 / 3980 .[ 332 / 3520 ]. 376 / 3500
1,000..362 / 4145 .[ 345 / 3600 ]. 387 / 3625
2,000..381 / 4220 .[ 360 / 3680 ]. 400 / 3750
3,000..398 / 3940 .[ 375 / 3465 ]. 412 / 3405
4,000..394 / 3460 .[ 375 / 2965 ]. 413 / 2925
5,000..388 / 3060 .[ 373 / 2480 ]. 410 / 2455
6,000..382 / 2985 .[ 367 / 2025 ]. 405 / 2025
7,000..376 / 2230 .[ 362 / 1635 ]. 399 / 1605
8,000..367 / 1745 .[ 356 / 1265 ]. 389 / 1160
9,000..356 / 1310 .[ 348 / -.940 ]. 367 / -.765

Full Throttle Height: 398.5 mph./2,957 m. .[ 378 mph./3,215 m. ]. .415 mph./3,170 m.
Critical Altitude: 4360 fpm./2,225 m. .[ 3720 fpm./2,438 m. ]. .3785 fpm./2,255 m.

Kevin J · Jan 9, 2019

CORSNING said:
Thank you all for a great discussion. I am thankful because these discussions
force me to dig through my files and others more deeply, a great learning
process.
I was recently forced to study these aircraft more closely and stumbled upon
an interesting note that I apparently had not caught before. ...The P-40N-1
was tested with external gas tank shackles in place. P-40F 41-13635 in report
Ser. No. FS-M-19-1578-A dated April 3, 1943 showed an increase of speed at
full throttle height of 8.5 mph. Speed was increased from 365.5 mph to 374 mph
at 18,100 ft. by the removal of the shackles (belly sway braces). This all mean the
speed of the P-40N-1 from sea level to FTH should be increased about 8 mph.
That would put the true war emergency maximum speeds of the P-40N-1 in clean
condition around 340 mph./S.L. and 386 mph./10,550 ft.
Just food for thought.

P-39N-1 @ 7,301 lb. .[ P-40N-1 @ 7,413 lb. ]. P-51A @ 8,000 lb.

Altitude / Speed / Climb
Meters / MPH / FPM
S.L........344 / 3980 .[ 332 / 3520 ]. 376 / 3500
1,000..362 / 4145 .[ 345 / 3600 ]. 387 / 3625
2,000..381 / 4220 .[ 360 / 3680 ]. 400 / 3750
3,000..398 / 3940 .[ 375 / 3465 ]. 412 / 3405
4,000..394 / 3460 .[ 375 / 2965 ]. 413 / 2925
5,000..388 / 3060 .[ 373 / 2480 ]. 410 / 2455
6,000..382 / 2985 .[ 367 / 2025 ]. 405 / 2025
7,000..376 / 2230 .[ 362 / 1635 ]. 399 / 1605
8,000..367 / 1745 .[ 356 / 1265 ]. 389 / 1160
9,000..356 / 1310 .[ 348 / -.940 ]. 367 / -.765

Full Throttle Height: 398.5 mph./2,957 m. .[ 378 mph./3,215 m. ]. .415 mph./3,170 m.
Critical Altitude: 4360 fpm./2,225 m. .[ 3720 fpm./2,438 m. ]. .3785 fpm./2,255 m.

Okay, so you tape the gun blast tubes to get these figures and when you enter combat and fire them then that takes off lets say 12 mph. In the case of the P-40N, you add the fuel tank back in and reinstate 2 guns, maybe another 6 mph loss. Then you need a dust filter, perhaps another 6 mph loss. Before you know it the crate you're flying is only doing 354 mph. Remove the belly tank shackles, I don't think so, because that's why you want the P-40N, for the range with the belly tank was better than the Spitfire VIII. As for that 398.5 mph for the Cobra, the report states that cooling requirements weren't met, so that's not something the Russians would have had to worry about in their standard ground level winter temperature of -20c. Did the USAAF use the P-51A in the CBI as a fighter, hell no, the P-40N was more manoeuvrable and speed was adequate for the task of a fighter; they used the P-51A as a fighter bomber and for counter air. Speed isn't everything.

Schweik · Jan 9, 2019

P-39N had excellent speed and climb down low though that is clear

CORSNING · Jan 9, 2019

Kevin J said:
Okay, so you tape the gun blast tubes to get these figures and when you enter combat and fire them then that takes off lets say 12 mph. In the case of the P-40N, you add the fuel tank back in and reinstate 2 guns, maybe another 6 mph loss. Then you need a dust filter, perhaps another 6 mph loss. Before you know it the crate you're flying is only doing 354 mph. Remove the belly tank shackles, I don't think so, because that's why you want the P-40N, for the range with the belly tank was better than the Spitfire VIII. As for that 398.5 mph for the Cobra, the report states that cooling requirements weren't met, so that's not something the Russians would have had to worry about in their standard ground level winter temperature of -20c.

Well sir, I believe in comparing apples to apples, comparing all WW2 fighters in their
interceptor mode condition. If you wish to converse about what happens when you
you begin to attach braces, sway bars, shackles and pylons then you open the door
for infinite possibilities. I believe there are several others on this forum that can 'School'
you in that area.

Did the USAAF use the P-51A in the CBI as a fighter,...
DAMN STRAIGHT!

...hell no, the P-40N was more manoeuvrable and speed was adequate for the task of a fighter;
they used the P-51A as a fighter bomber and for counter air.
You just answered your own question.

Speed isn't everything.[/QUOTE]
No, it is only life itself. Maximum speed isn't everything. The ability to maneuver and
escape or re-engage rapidly is.

Shortround6 · Jan 9, 2019

Trying to figure out how to make graphs,

Here is an attempt at Allison engine powers.

COuld be a little off, Please note that all the 8.80 supercharger gear engines track pretty well which is what I would expect. This is without RAM.
Upper limit at 25,000f t comes from an Allison chart for the -33 engine but doesn't seen out of line for climb numbers for later engines.

P-39 vs P-40

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