Wasn't the P-51 the best escort fighter of the war?

Navalwarrior · Jan 16, 2020

drgondog said:
The chart below is in mid final draft format, extracted from flight test data supplied by both Mike Williams and Kurfurst. There are still errors on the chart including labels. i.e. the Bf 109G-6 curves are for a DB605AS, the P-47D is a D-10 w/R2800-63 w/WI @56" and correct through the -16 series as far as Hp although the succeeding P-47D grew in weight. The plots for both the P-38J-15 and P-47D-10 for speed and climb are optimistic as the only test flights are at ~97% full combat load out (internal) Gross Weight. The P-51 is with full load out including full internal 269 gallons. ALL performance plots are shown without wing racks. The Bf 109 is the least affected with the Schlob 503, next is the Single C/L rack for the P-47D, next is the P-51B, then Fw 190A w/ETC 501, then last the P-38 J with twin pylons. With Wing Rack mods the P-47D was worst of all.

All of my plots are extracted from AAF and LW flight test data, clean, to provide a common benchmark for comparisons. It may be interesting to note that the P-51D compared to P-51B-15 w/1650-7 at the same Gross Weight (i.e full internal fuel -269gal for P-51B @9600 lbs WITHOUT RACKs, 184 gal internal for P-51D @9600lbs WITH racks) The D outclimbed the B and was faster at all altitudes.

For all that express comparative performance beliefs based on Max Speed or Max ROC, note from the chart that 'It Depends' - also note the for the ETO battles for control of German skies what the comparisons are for 15-30K altitudes.

Loss Rate comparison - before getting giddy in comparing ETO combat losses wrt to P-51 vs P-47, ponder a bit on these thoughts; The oil cooler vulnerability of the P-47 was about the same as the F4U and the P-47 was also vulnerable to a hit to the turbo. The ranges flown and the range to return to base for a Mustang was 50% greater on the average when strafing heavily defended ground targets for both the P-47D and F4U (WWII and Korea). Yet the per sortie loss of the P-51D was about the same as F4U in Korea - in perhaps a more lethal flak environment in Korea.

Big Week comparisons: First - the number of P-47D FGs = 11, P-38J = 2, P-51B =2. Second, the experience levels of only four P-47D FG's was less than the most experienced (354th FG) Mustang Group. The least experienced FG in Big Week was the new 357th FG Mustang group with 9 days under its belt.

Feb 20 thru 25 - - P-38 9-2-5 for 4 losses; P-47 137.5-14-29 for 17 losses; P-51 66.5-8-32 for 9 losses. VC Sources Dr Frank Olynyk PhD which also is supported by USAF 85. Loss Source Freeman's Mighty Eighth War Diary. The last time the cumulative totals of all 8th and 9th AF P-47D in escort roles exceeded the P-51B was March 15, less than three weeks afterwards.

View attachment 566845

eagledad said:
Hello Peter Gunn

It certainly looks like the P-38 wasn't getting the job done when one looks at the claims. However, to score claims, one must be in the area of action. It appears that at least one group (the 20th) was assigned target support, which I understand means joining the bombers 3 to 5 minutes before they bombed, and then escorting them back to England after coming off the target. Thus, they would not be involved in combat with the initial German interception, and would be themselves relieved about the time the refueled and rearmed German interceptors were attacking the homeward bound bombers.
Please see
Missions 001 - 025

for Big Week mission reports for the 20th FG.

To summarize, it appears that at least half of the P-38 force was placed in an area, where German fighters were less likely to be encountered (not that they would not be encountered). This may be one reason that the P-38 did not make as many claims.

Just my 2 cents worth.

Eagledad

Resp:
I like your two cents!
I wonder how many of the P-51 pilots got combat experience in another fighter before migrating to the P-51?
And conversely, how many P-38s pilots did not have the benefit of prior combat experience in another type? James Howard flew P-40s in Burma before joining the first ETO Mustang unit in late 1943. Just thinking out loud.

This may be a little off topic, and I have no actual data to support what I'm about to say. A US Marine, who is still living, flew FM-2s, F4U-Ds in 1944 and 1945, respectively . . . and F4U-4s Korea as ground support for NATO forces . . . said the F-51 had a greater loss rate than the F4U. He also said the F-51 pilots normally would not get low enough to accurately place their ordinance.

Peter Gunn · Jan 16, 2020

Navalwarrior said:
Resp:
I like your two cents!
I wonder how many of the P-51 pilots got combat experience in another fighter before migrating to the P-51?
And conversely, how many P-38s pilots did not have the benefit of prior combat experience in another type? James Howard flew P-40s in Burma before joining the first ETO Mustang unit in late 1943. Just thinking out loud.

This may be a little off topic, and I have no actual data to support what I'm about to say. A US Marine, who is still living, flew FM-2s, F4U-Ds in 1944 and 1945, respectively . . . and F4U-4s Korea as ground support for NATO forces . . . said the F-51 had a greater loss rate than the F4U. He also said the F-51 pilots normally would not get low enough to accurately place their ordinance.

In response to what the Marine pilot said, and this is why I do not trust anecdotal types of evidence but here's what I've seen posted for loss rates in Korea:

Combat Losses:
F-51 = 341
F4U
.............145 Navy
.............164 Marines
..............16 AU1 - Not sure if Navy or Marines
=======
Total 325

Total Losses (To all causes):
F-51 = 474
F4U
.............267 Navy
.............206 Marines
..............21 AU1
=======
Total 494

I have no clue/evidence of whether or not the Mustangs did not get low enough to accurately place their ordinance, which, considering loss rates etc., sounds a bit of a disservice to the F-51 jocks.

I'm not too good at statistics but I don't see a whole percentage point difference there.

fubar57 · Jan 16, 2020

I'll go through this later if I find the time...239 pages, alphabetical order. Right off the get-go, 3 Corsairs down

michael rauls · Jan 16, 2020

drgondog said:
The chart below is in mid final draft format, extracted from flight test data supplied by both Mike Williams and Kurfurst. There are still errors on the chart including labels. i.e. the Bf 109G-6 curves are for a DB605AS, the P-47D is a D-10 w/R2800-63 w/WI @56" and correct through the -16 series as far as Hp although the succeeding P-47D grew in weight. The plots for both the P-38J-15 and P-47D-10 for speed and climb are optimistic as the only test flights are at ~97% full combat load out (internal) Gross Weight. The P-51 is with full load out including full internal 269 gallons. ALL performance plots are shown without wing racks. The Bf 109 is the least affected with the Schlob 503, next is the Single C/L rack for the P-47D, next is the P-51B, then Fw 190A w/ETC 501, then last the P-38 J with twin pylons. With Wing Rack mods the P-47D was worst of all.

All of my plots are extracted from AAF and LW flight test data, clean, to provide a common benchmark for comparisons. It may be interesting to note that the P-51D compared to P-51B-15 w/1650-7 at the same Gross Weight (i.e full internal fuel -269gal for P-51B @9600 lbs WITHOUT RACKs, 184 gal internal for P-51D @9600lbs WITH racks) The D outclimbed the B and was faster at all altitudes.

For all that express comparative performance beliefs based on Max Speed or Max ROC, note from the chart that 'It Depends' - also note the for the ETO battles for control of German skies what the comparisons are for 15-30K altitudes.

Loss Rate comparison - before getting giddy in comparing ETO combat losses wrt to P-51 vs P-47, ponder a bit on these thoughts; The oil cooler vulnerability of the P-47 was about the same as the F4U and the P-47 was also vulnerable to a hit to the turbo. The ranges flown and the range to return to base for a Mustang was 50% greater on the average when strafing heavily defended ground targets for both the P-47D and F4U (WWII and Korea). Yet the per sortie loss of the P-51D was about the same as F4U in Korea - in perhaps a more lethal flak environment in Korea.

Big Week comparisons: First - the number of P-47D FGs = 11, P-38J = 2, P-51B =2. Second, the experience levels of only four P-47D FG's was less than the most experienced (354th FG) Mustang Group. The least experienced FG in Big Week was the new 357th FG Mustang group with 9 days under its belt.

Feb 20 thru 25 - - P-38 9-2-5 for 4 losses; P-47 137.5-14-29 for 17 losses; P-51 66.5-8-32 for 9 losses. VC Sources Dr Frank Olynyk PhD which also is supported by USAF 85. Loss Source Freeman's Mighty Eighth War Diary. The last time the cumulative totals of all 8th and 9th AF P-47D in escort roles exceeded the P-51B was March 15, less than three weeks afterwards.

View attachment 566845

Very interesting chart. If I'm reading it properly it says the best climb for the p47d is about 2300 fpm?
All the other types on the chart are about what is commonly cited but the p47D is way different than the usual. Doesn't nescesarily mean it's wrong but I do find it a curiosity.

Dan Fahey · Jan 16, 2020

Peter Gunn said:
In response to what the Marine pilot said, and this is why I do not trust anecdotal types of evidence but here's what I've seen posted for loss rates in Korea:

Combat Losses:
F-51 = 341
F4U
.............145 Navy
.............164 Marines
..............16 AU1 - Not sure if Navy or Marines
=======
Total 325

Total Losses (To all causes):
F-51 = 474
F4U
.............267 Navy
.............206 Marines
..............21 AU1
=======
Total 494

I have no clue/evidence of whether or not the Mustangs did not get low enough to accurately place their ordinance, which, considering loss rates etc., sounds a bit of a disservice to the F-51 jocks.

I'm not too good at statistics but I don't see a whole percentage point difference there.

If you go to COWAR archives built by Cookie Sewell....the Mustang had a slightly less Loss ratio per sortie than the Corsair.
Mustangs could stay on station longer because of their range. Corsairs launched from Carriers and traveled to land targets.
Corsair did better on land but had several accidents on takeoff RTCarrier. Mustangs began as an attack aircraft as the A36 and were very accurate.
So the comment the Mustang was not accurate is proven otherwise. Both Corsair and Mustang were damn effective destroying way more than their respective losses. The Mustang also had a higher cruise speed and could get to targets a bit faster.

One other observation..the P47 would not been suitable because even just fully fueled and machine guns took a longer airstrip to takeoff from than a fully loaded Mustang loaded up with ordinance. The airfields the Mustangs flew out of the first year were built by the Japanese and were very short. P47s would have required a bomber length field. Would have been just as vulnerable to AAA as the Corsair and Mustang.

DarrenW · Jan 16, 2020

michael rauls said:
Very interesting chart. If I'm reading it properly it says the best climb for the p47d is about 2300 fpm?
All the other types on the chart are about what is commonly cited but the p47D is way different than the usual. Doesn't nescesarily mean it's wrong but I do find it a curiosity.

To be fair, the climb rate given for the P-47D-6 on the chart is what one would see under MILITARY power settings (52" Hg) and not with water injection. With 56" Hg boost the climb rate of the P-47D-10 on Mike Williams' website is substantially higher but still lower than most of it's contemporaries shown on Bill's chart.

P-47 Performance Tests

P-47D-10 / AAF No. 43-75035/ Report Date: 11 Oct 1943/ 56" Hg

P-47D-6 / AAF No. 42-74616/ Report Date: 28 Sep 1943 / 52" Hg

P-39 Expert · Jan 16, 2020

drgondog said:
Note - the above comparison II as shown does not include Bf 109G-6AS @ 1.42ata. Shift the existing curve to inflect at 22,000 feet - 409mph - and for climb, move the curve to 3750fpm for the 109G-6AS at SL

Wonder how many G-6AS were built?

DarrenW · Jan 16, 2020

P-39 Expert said:
Wonder how many G-6AS were built?

According to Messerschmitt Bf 109 F,G, & K Series by Jochen Prien & Peter Rodeike, there were only 226 BF-109G-6/AS with MW 50 injection produced and 460 converted from standard G-6 airframes during the months of April - August 1944. Apparently production shifted rather quickly to the G-14 thereafter. I'm uncertain of how many were manufactured/converted without the MW 50 system.

eagledad · Jan 16, 2020

Drgondog

My conclusion was based on the Briefing notes for the 20th FG for FO 250, 24th February 1944. They are attached below. In all fairness, the 354th was credited with 1 kill, as was the 20th. In return, the 20th lost 2 ships, one to mechanical problems, and one to running out of fuel. (data from The Mighty Eighth War Diary, and Fighter Units and Pilots of the the 8th Air Force).

Eagledad

Dan Fahey · Jan 16, 2020

DarrenW said:
To be fair, the climb rate given for the P-47D-6 on the chart is what one would see under MILITARY power settings (52" Hg) and not with water injection. With 56" Hg boost the climb rate of the P-47D-10 on Mike Williams' website is substantially higher but still lower than most of it's contemporaries shown on Bill's chart.

P-47 Performance Tests

P-47D-10 / AAF No. 43-75035/ Report Date: 11 Oct 1943/ 56" Hg

P-47D-6 / AAF No. 42-74616/ Report Date: 28 Sep 1943 / 52" Hg

PEP 44-1 130/150 fuel the P47 for short periods could go to 70 inches with Water Injection
This boost was used on the P47M and max climb rate was 3500 ft /min.
Even when 65 inches was used the tuning and maintenance issues were still considerable..
Hence the delay of the M Thunderbolt.

Liquid cooled engines handled the additional boost better.
Experimentation went well past 130 inches pushing engines well past 2 hp per cuin.
Reno Merlin's are pushed closer to 2.5 hp/cuin.
Radial engines barely make 1 hp per cuin.

The Merlin H Mustangs were successfully boosted to 91 inches.
That was before the much better Merlin Transportation heads were available.

The only radial engine that exceeded 1:1 hp/cuin that was the Turbo Compound CW3350 at 3500 hp

One other observation Mustang often exceeded 75 inches managing 81 inches in combat.
Just looked at a few combat reports..

Tkdog · Jan 17, 2020

eagledad said:
Hello Peter Gunn

It certainly looks like the P-38 wasn't getting the job done when one looks at the claims. However, to score claims, one must be in the area of action. It appears that at least one group (the 20th) was assigned target support, which I understand means joining the bombers 3 to 5 minutes before they bombed, and then escorting them back to England after coming off the target. Thus, they would not be involved in combat with the initial German interception, and would be themselves relieved about the time the refueled and rearmed German interceptors were attacking the homeward bound bombers.
Please see
Missions 001 - 025

for Big Week mission reports for the 20th FG.

To summarize, it appears that at least half of the P-38 force was placed in an area, where German fighters were less likely to be encountered (not that they would not be encountered). This may be one reason that the P-38 did not make as many claims.

Just my 2 cents worth.

Eagledad

It's this sort of thing that simple numbers can't tell us. Each of these aircraft had strengths and weaknesses relative to the enemy and each other. By deploying them differently across the battlefield the allies could hope to play to the strengths. The fighter pilots didn't just go off to shoot at the bad guy. They flew highly technical escort missions with specific roles and objectives. All these years later it is hard to extract those details with clarity.

P-39 Expert · Jan 17, 2020

DarrenW said:
According to Messerschmitt Bf 109 F,G, & K Series by Jochen Prien & Peter Rodeike, there were only 226 BF-109G-6/AS with MW 50 injection produced and 460 converted from standard G-6 airframes during the months of April - August 1944. Apparently production shifted rather quickly to the G-14 thereafter. I'm uncertain of how many were manufactured/converted without the MW 50 system.

Thanks, almost 700.

drgondog · Jan 17, 2020

eagledad said:
Drgondog

My conclusion was based on the Briefing notes for the 20th FG for FO 250, 24th February 1944. They are attached below. In all fairness, the 354th was credited with 1 kill, as was the 20th. In return, the 20th lost 2 ships, one to mechanical problems, and one to running out of fuel. (data from The Mighty Eighth War Diary, and Fighter Units and Pilots of the the 8th Air Force).

Eagledad

Well the 2TF was comprised of 238 effectives ~ 5 Combat boxes of 50 in trail. Splitting up the Groups (frequently done to provide escort for a ten mile track would suggest the 354 in high cover, have one out front and one middle and one trail with the 20th patrolling the flanks.

DarrenW · Jan 17, 2020

Dan Fahey said:
PEP 44-1 130/150 fuel the P47 for short periods could go to 70 inches with Water Injection
....

Yes, with a boost pressure of 70" Hg the performance of the P-47 increased even further, but the comparative charts found in post #98 were for periods before the higher octane fuel was available for operations. With 100/130 fuel and using water injection the P-47 was initially cleared for a maximum of 56" Hg of manifold pressure. This happened in November 1943. Later in 1944 it was cleared for 64" Hg but modified water jets were required to safely obtain this.

One thing that I failed to mention was that both P-47Ds shown in the earlier charts used the the older 12 foot "toothpick" propeller which didn't have the greatest efficiency in a climb. One can expect the ROC to increase by about 250 fpm with the improved "paddle blade" Curtis 836 and Hamilton Standard types, which began to reach squadrons by the end of 1943. With 64" Hg (2600 hp) there was even a further increase of 500 fpm across the board.

http://www.wwiiaircraftperformance.org/p-47/p-47d-75035-fig2.jpg

Testing was accomplished at both 56" and 64" Hg. You will note that the maximum speed of the P-47 actually decreased with the "improved" Curtis propeller. Even so, the better climb rate achieved was reason enough to replace the older, less efficient Curtis propellers. The Hamilton propeller seems to be the clear winner here with both improved level speed and climb over the earlier propellers.

P-39 Expert · Jan 17, 2020

DarrenW said:
Yes, with boost pressure beyond 56" (64 and 70") the performance of the P-47 increased even further, but the comparative charts found in post #98 were for periods before the higher octane fuel was available for operations. With 100/130 fuel and using water injection the P-47 was cleared for a maximum of 56" Hg of manifold pressure.

One thing that I failed to mention was that both P-47Ds shown in the charts used the the older 12 foot "toothpick" propeller which didn't have the greatest efficiency in a climb. One can expect the ROC to increase by about 250 fpm with the improved "paddle blade" Curtis 836 and Hamilton Standard types, which began to reach squadrons by the end of 1943. With 64" Hg (2600 hp) there was even a further increase of 500 fpm across the board:

http://www.wwiiaircraftperformance.org/p-47/p-47d-75035-fig2.jpg

Testing was accomplished at both 56" and 64" Hg. You will note that the maximum speed of the P-47 actually decreased with the "improved" Curtis propeller. Even so, the better climb rate achieved was reason enough to replace the older, less efficient Curtis propellers. The Hamilton propeller seems to be the clear winner here with both improved level speed and climb over the earlier propellers.

Looks like the graph is dated in March of 1944. Unless they are in combat that month they will have missed the air superiority win and will shortly be headed for ground attack. The P-47s that did engage the Luftwaffe during this period had relatively low climb rates. And were just then getting adequate external tanks.

DarrenW · Jan 17, 2020

P-39 Expert said:
Looks like the graph is dated in March of 1944. Unless they are in combat that month they will have missed the air superiority win and will shortly be headed for ground attack. The P-47s that did engage the Luftwaffe during this period had relatively low climb rates. And were just then getting adequate external tanks.

Dean's book states that starting in December 1943 the new propellers were fitted to P-47s in the field "one squadron at a time". He also states that with the new propeller and water injection the Thunderbolt could beat the FW-190 in a climb below 15,000 ft. I don't know how long it took for all T-bolt units to get the new propeller but I'm sure this wasn't accomplished overnight so there was a period where both old and new propellers were in service at the front.

Dan Fahey · Jan 17, 2020

P-39 Expert said:
Agree. And then it didn't get into combat until May '43, and then with no provision for mounting drop tanks. Could barely get to the coast of France before it had to turn around.

First drop tanks were in August, one small 75 gallon belly tank at first, then 110 gallon tanks. The P-38H would be arriving in October and the P-51B in December. Air superiority achieved after Big Week in February. P-47 was used as escort about 6 months and then only out to about 375 miles.

A really big expensive fighter that was fast but couldn't do much else. Still better than a P-38 at keeping the pilot alive. Good at ground attack though.

The Thunderbolt was a big bulky plane and combat range of a Spitfire !
It was more reliable than the P38.
The P40 could climb quicker up to 18k.

Dan Fahey · Jan 17, 2020

Dan Fahey said:
The Thunderbolt was a big bulky plane and combat range of a Spitfire !
It was more reliable than the P38.
The P40 could climb quicker up to 18k.

Prove me wrong if you disagree

Conslaw · Jan 17, 2020

The P-47 pilots who talked about the impact of the paddle-bladed propeller said it was not so much in the rate of climb but that the P-47 could then climb steeper and pursue an enemy into the climb In such case, the pursuing aircraft does not have to be faster than the evading aircraft. The bullets have to be faster.

For that matter, the P-51's climb rate on paper was inferior to the later Bf-109 marks, but the pilot accounts don't seem to fret over that. Likely it's because the P-51's zoom climb and energy retention was excellent. When the P-51 starts the engagement with a speed advantage the zoom climb ability can make up for a lower basic climb rate. Same for the P-47, but the P-51 seemed to be the master of the zoom climb (with the exception of the Me-262, of course.

I will try to find passages to support this. If somebody beats me to it, so be it.

MiTasol · Jan 17, 2020

Navalwarrior said:
Part of the problem/issue with the P-47 falls on USAAC/USAAF prohibition against manufacturers (that made fighters for their Air Corps) making them drop tanks capable (no external fuel stores) that put the P47 at a major disadvantage until @ March/April 1944

I have never heard of this prohibition. When was it introduced and why?
All USAAC P-40D (serials 40-359 to 381 inclusive) and subsequent P-40 aircraft had drop tanks so why did the USAAC/F prohibit them on later aircraft? That does not make sense.

Wasn't the P-51 the best escort fighter of the war?

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