P-47N Thunderbolt vs. F4U-4 Corsair - Which was superior?

[USS Enterprise CV-6]

The Corsair and the P-47N were 2 of the best planes in WW2. If they were attacking each other the Corsair could get behind it and tear open the P-47s canopy. I would choose Corsair for the better fighter and fighter bomber, but P-47N for ground attack.

 

[windswords]

1. High altitude speed - P-47
2. Low altitude speed - F4U
3. High altitude performance - P47
4. Firepower - P-47
5. Low altitude performance - F4U
6. Turn - F4U
7. Roll - P-47?
8. Dive - P-47
9. Ruggedness - P-47

Assuming this is a 1 to 1 combat (with "clean" aircraft, no bombs, rockets etc.) Then the altitude is the big factor. Up high (25k feet +) the Thunderbolt has the clear advantage. Below 20k, it's the Corsair. At 20 - 25k I don't know. At any altitude, if the P-47 does not engage in the classic dogfight, it should do well. Turn and climb were not the most important aspects of fighter aircraft in WWII. If they were, then the A6M and Ki-43 would have been the best fighters of the war.

IF the pilots were of equal skill and they knew what their planes could and could not do, then I would give the advantage to the Thunderbolt. If the P-47 pilot is foolish enough to dogfight with the F4U then the result would be the same as if he would dogfight a Spitfire or a Zero.

 

[BiffF15]

Concour.

Cheers,
Biff

 

[Dawncaster]

F4U-4 with 234gal fuel curve from SAC (use clean condition, +8kn at S.L and +10kn at 20600ft) http://www.wwiiaircraftperformance.org/f4u/f4u-4.pdf
P-47M with 205gal fuel curve from Report No. ES-300 http://www.wwiiaircraftperformance.org/p-47/p-47m-republic-wepchart.jpg
P-47N with 205gal fuel curve from Report No. ES-302-A http://www.wwiiaircraftperformance.org/p-47/p-47n-republic-wep.jpg
P-47N with 570gal fuel curve from Comparison of P-47D, P-47M and P-47N Performance http://www.wwiiaircraftperformance.org/p-47/p47m-n-speed.jpg

F4U-4's full internal fuel capacity is 234gal
P-47M's full internal fuel capacity is 370gal
P-47N's full internal fuel capacity is 570gal

 

[mig-31bm]

View attachment 258287

F4U-4 with 234gal fuel curve from SAC (use clean condition, +8kn at S.L and +10kn at 20600ft) http://www.wwiiaircraftperformance.org/f4u/f4u-4.pdf
P-47M with 205gal fuel curve from Report No. ES-300 http://www.wwiiaircraftperformance.org/p-47/p-47m-republic-wepchart.jpg
P-47N with 205gal fuel curve from Report No. ES-302-A http://www.wwiiaircraftperformance.org/p-47/p-47n-republic-wep.jpg
P-47N with 570gal fuel curve from Comparison of P-47D, P-47M and P-47N Performance http://www.wwiiaircraftperformance.org/p-47/p47m-n-speed.jpg

F4U-4's full internal fuel capacity is 234gal
P-47M's full internal fuel capacity is 370gal
P-47N's full internal fuel capacity is 570gal

was the p-47N able to use 90 in Hg fuel ? , it seem that p-47n is quite inferior except at very high altitude
btw iam quite suprise that at about 21000 feet the F4u-4 was actually as fast as a clean P-51H ( no rack ) even though it look alot draggier with the nose

 

[tomo pauk]

The maximum manifold pressure both for the P-51M and -N was 72 in Hg, available both by use of water-methanol injection and at least 115/145 fuel.

Dawncaster,

Are the graph values for the P-47s with or without racks?

 

[mig-31bm]

The maximum manifold pressure both for the P-51M and -N was 72 in Hg, available both by use of water-methanol injection and at least 115/145 fuel.

Dawncaster,

Are the graph values for the P-47s with or without racks?

you mean p-47M ?

 

[tomo pauk]

Both -M and -N; they used the same engine during the war.

 

[Dawncaster]

The maximum manifold pressure both for the P-51M and -N was 72 in Hg, available both by use of water-methanol injection and at least 115/145 fuel.

Dawncaster,

Are the graph values for the P-47s with or without racks?

in my opinion, 1,2 clean, 3 had x2 wing racks

1, P-47M with 205gal fuel, Report No. ES-300 use "Design Useful Load"
2, P-47N with 205gal fuel, Report No. ES-302-A use "normal gross weight with normal load"
3, P-47N with 570gal fuel, Comparison of P-47D, P-47M and P-47N use "combat condition"

here is later F-47N SAC

http://www.alternatewars.com/SAC/F-47N_Thunderbolt_SAC_-_17_May_1950.pdf

max speed is 385kn at 35000ft, gross weight 17228lb.

graph labelled "clean" but mission profile said take-off with three drop tanks at 20837lb, so 385kn is maximum speed with x3 racks.

and power rating is 2800BHP at critical altitude with 100/130 fuel, 115/145 fuel is not required for 2800BHP.

here is pratt whitney aircraft engines model designations and characteristics.

R-2800-57, -73, -77, -81 use 100/130 fuel.

in my opinion, R-2800 + turbocharger can handle 3000BHP with 115/145 fuel.

here is F4U-3 october 44 test.

3000BHP with 73" hg at 28000ft.
2800BHP with 68" hg at 30000ft.
2600BHP with 63" hg at 33000ft.

I'm not sure that F4U-3 use 115/145 fuel, but in same test F4U-4 use 115/145 fuel with 70" hg at 2650BHP.

so, if P-47M/N can use 115/145 fuel, handle around 3000BHP and better performance. I think.

but I'm not sure P-47M/N use 115/145 fuel with higher than 72" hg.

 

[tomo pauk]

Thanks for setting me straight re. fuel PN rating used on the P-47M/N.

IMO, most of the extra performance in the war emergency rating of the quoted F4U-4 seem to be emanating from using the 115/145 fuel. Such fuel is specified in the document you've linked (http://www.wwiiaircraftperformance.org/f4u/f4u-4.pdf). The altitude where the max speed is achieved is at ~20500 ft, against the 26000 ft for the data from 1946 (link); both for auxiliary supercharger in high gear. In low gear, the max speed is at 14000 ft for the engine using the 115/145 fuel, and at 20000 ft for the A/C from 1946 chart. While in WER, the faster A/C does not use the 'neutral' gear - there is no suitably low altitude for it, if the full boost enabled by use of 115/145 fuel and ADI?
Unfortunately, I don't know both the date of the chart of the faster A/C and the fuel used by the 1946 A/C.

All this said still does not explain the better altitude performance of the faster A/C (ie. above 27000 ft) - anybody want to take a stab?

Attached are the graphs, both for 1946 F4U-4 and the 'better' one, red line is the performance of the better A/C, for a more convenient comparison. Both maximum speeds are with two racks, both capped. Blue squares are speeds at SL and at 30000 ft of the P-47N with ~200 gals of fuel, the blue dots are for the -N with 556 gals, taken from above graph. Fuel is the 100/130 for the -N.

 

[pbehn]

Corsair everytime, it was carrier based and stayed in the military after 1945, because it still had a role to play.

 

[Shortround6]

From Wiki;

"The USAAF Strategic Air Command had P-47 Thunderbolts in service from 1946 through 1947.

The P-47 served with the Army Air Forces (United States Air Force after 1947) until 1949, and with the Air National Guard until 1953, receiving the designation F-47 in 1948. P-47s also served as spotters for rescue aircraft such as the OA-10 Catalina and Boeing B-17H."

Republic was moving on to jets a bit better than Vaught did in 1944-47,in part due to Vaught having to use Westinghouse jet engines.

 

[USS Enterprise CV-6]

From Wiki;

"The USAAF Strategic Air Command had P-47 Thunderbolts in service from 1946 through 1947.

The P-47 served with the Army Air Forces (United States Air Force after 1947) until 1949, and with the Air National Guard until 1953, receiving the designation F-47 in 1948. P-47s also served as spotters for rescue aircraft such as the OA-10 Catalina and Boeing B-17H."

Republic was moving on to jets a bit better than Vaught did in 1944-47,in part due to Vaught having to use Westinghouse jet engines.

Just saying this, F-47 doesn't sound as cool as P-47

Also you make a good point. Also, Vought is spelled V-o-u-g-h-t. Don't worry about it, not a word that's gonna be on a spelling test

 

[pbehn]

From Wiki;

"The USAAF Strategic Air Command had P-47 Thunderbolts in service from 1946 through 1947.

The P-47 served with the Army Air Forces (United States Air Force after 1947) until 1949, and with the Air National Guard until 1953, receiving the designation F-47 in 1948. P-47s also served as spotters for rescue aircraft such as the OA-10 Catalina and Boeing B-17H."

Republic was moving on to jets a bit better than Vaught did in 1944-47,in part due to Vaught having to use Westinghouse jet engines.

Thanks shortround but I think you get what I mean. In 1945 no military would scrap all aircraft, the pilots need to practice flying.

 

[Shortround6]

Not just practice, the jets were not quite ready for all round combat duty for several more years (1948?) as engine life and reliability was a bit on the short side. For some reason (some say logistics) the P-51s tended to stay in the Pacific and on/near the west coast while the P-47 equipped units tended to be in the Eastern United states. This did affect deployment to Korea.

 

[Dawncaster]

Thanks for setting me straight re. fuel PN rating used on the P-47M/N.

IMO, most of the extra performance in the war emergency rating of the quoted F4U-4 seem to be emanating from using the 115/145 fuel. Such fuel is specified in the document you've linked (http://www.wwiiaircraftperformance.org/f4u/f4u-4.pdf). The altitude where the max speed is achieved is at ~20500 ft, against the 26000 ft for the data from 1946 (link); both for auxiliary supercharger in high gear. In low gear, the max speed is at 14000 ft for the engine using the 115/145 fuel, and at 20000 ft for the A/C from 1946 chart. While in WER, the faster A/C does not use the 'neutral' gear - there is no suitably low altitude for it, if the full boost enabled by use of 115/145 fuel and ADI?
Unfortunately, I don't know both the date of the chart of the faster A/C and the fuel used by the 1946 A/C.

All this said still does not explain the better altitude performance of the faster A/C (ie. above 27000 ft) - anybody want to take a stab?

Attached are the graphs, both for 1946 F4U-4 and the 'better' one, red line is the performance of the better A/C, for a more convenient comparison. Both maximum speeds are with two racks, both capped. Blue squares are speeds at SL and at 30000 ft of the P-47N with ~200 gals of fuel, the blue dots are for the -N with 556 gals, taken from above graph. Fuel is the 100/130 for the -N.

View attachment 258373

ACP use 100/130 fuel with 2380BHP at S.L
SAC and 1944 test use 115/145 fuel with 2650BHP at S.L

with same model engine, higher pressure = higher power but lower critical altitude.

case of F4U-1

60.2/59.8"hg, critical altitude 14300/19850ft
62.2/61.8"hg, critical altitude 13200/18800ft
63.9/63.4"hg, critical altitude 12200/17900ft

60.2"hg to 63.9"hg = +3.7"hg, + around 150BHP, critical altitude - around 2000ft.

case of F4U-3

63"hg, critical altitude 32500ft.
68"hg, critical altitude 30000ft.
73"hg, critical altitude 27500ft.

63"hg to 73"hg = +10"hg, +400BHP, critical altitude -5000ft.

case of F4U-4

70"hg with 115/145 fuel to 60"hg with 100/130ful = +10"hg, +200BHP, critical altitude -6000ft.

high blower critical altitude, 26000ft vs 20000ft = -6000ft.
low blower critical altitude, 20000ft vs 14000ft = -6000ft.

and F4U-4 wth 100/130 fuel, critical altitude of natual blower is only 1500ft.

1500ft - 6000ft = -4500ft, lower than sea level.

so in my opinion, there is no natual blower stage needed for WEP with 115/145 fuel.

new graph, F4U-4 60"hg added.

 

[windswords]

Corsair everytime, it was carrier based and stayed in the military after 1945, because it still had a role to play.

The only reason it stayed in service after the war and "had a role to play" was because the navy did not have a jet fighter bomber. Once the F9F was available in numbers it took over that role, at least on carriers that could handle the load/landing speed. The P-47 was phased out because the air force had jets and the P-51's left were way cheaper to keep and maintain. Same for the P-38.

One thing I forgot to mention was the increased range of the P-47N. If you only had land bases available, then the long legs of the N would make it preferable to the Corsair. If you have carriers it doesn't matter unless you can't get the carriers close enough to your target.

 

[swampyankee]

P-47N vs F4U-4? Whichever one your pilots like better

Incidentally, the USN considered the 20mm Hispano roughly three times as effective, air to air, as the 0.5 in M2, so it would be something like twice as effective as the 0.5 in M3. Also, the Corsair had some fabric covered control surfaces, not fabric covered wings. Fabric covered control surfaces are easier to balance, so they may be less prone to flutter.

 

[tomo pauk]

If I'm not mistaking it badly, the P-47M and -N were the only aircraft that flew in combat with 3-stage compressor system. The air 1st compressed by a turbo-compressor with two compressor stages, then, once cooled via inter-cooler, compressed by 3rd impeller, this one integral with the engine.
Comments/corrections?

 

[Shortround6]

I believe they were actually two stages, the turbo (one stage) fed the inter-cooler which fed the engine supercharge ( one stage-one speed).

Same set up as earlier P-47s except 1. new "C" engine with much more cooling fin area per cylinder required less cooling air for the same power level or allowed more power from the same amount of cooling air. 2, engine supercharger may have been modified. 3, Turbo was the CH-5 instead of earlier models with lower allowable rpm, 4 turbo control was changed.