P-47: Range, Deceit and Treachery

[drgondog]

I appreciate Greg doing all of the research to set the record straight regarding various aspects of the fighters used in Europe and the Pacific. I have been aware of the misinformation regarding the "range" comparison of the P51 vs the P47 using drop tanks since I first started reading accounts of aircraft performance over 50 years ago as a boy. I believe the Mustang, while being a great fighter, is very over rated compared to the Thunderbolt and gets that reputation by comparing the P51 of 1944 with the P47 of 1943 and completely ignoring the thunderbolt advancements of 1944 & 45. Greg finding that order from Hap Arnold stopping the purchase of drop tanks clears up a lot of the mystery of what was going on in 1943 regarding fighter range.

If you are laboring under the assumption that Doolittle 'plotted' against Republic to cast the P-47D in an unfavorable light, 'say it isn't so'.
Until the P-47D-25 entered limited combat operations in Mid May 1944, in limited quantities below squadron level strength, it was flying in mixed formations to the endurance radius of the earlier P-47Ds with only 305 gallons of internal fuel. It was incapable of target escort beyond Brunswick until late June 1944. By then most of the P-47D groups had converted to P-51B/C/D and three of the four P-38 groups converted by mid July.

The P-51B comparison in 1943 to the P-47D of early 1944 showed a demonstrable advantage over the pre -25D. In January 1944 when the P-51B/C arrived into combat ops With the 85 gallon mod (and no combat tanks), the P-51B could escort farther than the P-47D w/150gal external tank. When 2x75 gallon external tanks were added, the P-51B went to Poland and back while the P-47s turned back mid-Germany.

 

[gjs238]

I appreciate Greg doing all of the research to set the record straight regarding various aspects of the fighters used in Europe and the Pacific. I have been aware of the misinformation regarding the "range" comparison of the P51 vs the P47 using drop tanks since I first started reading accounts of aircraft performance over 50 years ago as a boy. I believe the Mustang, while being a great fighter, is very over rated compared to the Thunderbolt and gets that reputation by comparing the P51 of 1944 with the P47 of 1943 and completely ignoring the thunderbolt advancements of 1944 & 45. Greg finding that order from Hap Arnold stopping the purchase of drop tanks clears up a lot of the mystery of what was going on in 1943 regarding fighter range.

If you haven't already, you should post that on his YouTube page:

 

[drgondog]

Well, there were a few that had a radar operator back there, but I don't think he would have had such a nice camera.

By the way, as Warren Bodie points out in his book Thunderbolt, Gen Arnold may have signed out a letter forbidding drop tanks but in reality early in the war they were hanging them very commonly on P-40's and P-39's as well as 50 gal tanks on even the earliest P-38's, so that order did not seem to have any teeth. Note that the Mustang Mk I and Mk 1A did not have provisions for drop tanks. It was the RAF that appeared to be clueless about drop tanks, as was shown by those few special "Long Range" Spitfires with that hideous tank sticking out of the wing.

There are two separate discussions - Ferry tanks and Combat (self sealing) tanks. The US produced only Ferry tanks through most of 1943 despite Arnold ordering Combat tanks as a high priority to Materiel Command in Fighter Conference of Feb 1942.

The use of Ferry Tanks in combat was forbidden in AAC. The mention of Arnold in Bodie was convoluted in origin and specifically pointed out for conversation Kelsey had with Arnold about how the P-38s of 1st FG were flown to England in July 1942.

The order 'forbidding' dropping external tanks was issued by CO of VIII FC, Gen. Monk Hunter because the supply of 75 gal Combat tanks was still very limited in August - October 1943. The Fighter Group CO's basically told their pilots to ignore the order if combat was imminent.

As to the Mustang I and IA. True no provision for combat or external ferry tanks - but early 1941 NAA developed an auxiliary fuel cell housed in the gun bay 0f 18 gal enabling a 1500 mi ferry (or about a 500 mi combat radius with 2x50 cal guns in Mk I and camera). The P-51-NA had the same provision but USAAF never used it as removing 4x20mm eliminated all armament.

 

[Deleted member 68059]

If you haven't already, you should post that on his YouTube page:]

I offered him archive documents to fix serious errors / give additional info to two of his videos, he didn't seem to be interested. Which is a shame
as he obviously puts in a lot of work, and makes videos which thousands of people enjoy.

 

[MIflyer]

Well, the Mustang MkI/IA had a 1000 mile range on internal fuel alone, and given their use of the airplane, which was not for long range escort, that was more than enough and verged on twice the range of a Spitfire.

Were the paper tanks self-sealing?

 

[Peter Gunn]

I think drgondog should post on his YouTube stream, but I doubt a guy like this Greg ( NOT our GregP ) would be interested in anything that doesn't prove the theory behind the ax he is grinding.

 

[Zipper730]

I offered him archive documents to fix serious errors / give additional info to two of his videos

Just out of curiosity, what kind of errors?

 

[RCAFson]

I assume we've all read this and are familiar with it:

Development of the Long Range Escort Fighter

https://www.afhra.af.mil/Portals/16/documents/Studies/101-150/AFD-090529-044.pdf

See page 46 onward for a discussion of external tanks and initial refusal for these.

 

[Deleted member 68059]

Just out of curiosity, what kind of errors?

He was talking about why the Daimler-Benz was inverted, and had listed all the usual things people say in his video, I gave him a list that was written by Wolfram Eisenlohr, who was in charge of German aero engine development from 1938 to 1944. He wasnt very interested, that was more an attempt at a helpful addition than an "error" as such.

He then made a fairly big error in his P51 performance video, which claimed that the laminar flow wing was basically a legend which had built up and wasnt really very important and didnt work nearly as well as people thought it did. I mentioned 3 archive reports I had which stated the opposite (one was a Supermarine report, the other two were German windtunnel tests of the P51). He made it clear that he was perfectly happy and didnt want to alter anything. So there you go.

 

[Zipper730]

There are two separate discussions - Ferry tanks and Combat (self sealing) tanks. The US produced only Ferry tanks through most of 1943 despite Arnold ordering Combat tanks as a high priority to Materiel Command in Fighter Conference of Feb 1942.

Fascinating. What I'm confused about were these tanks the P-47 had which were nicknamed "babies" because of their bulged appearance -- just to be clear, these are the ferry tanks, and they can be jettisoned? They didn't look like they could be.

The use of Ferry Tanks in combat was forbidden in AAC. The mention of Arnold in Bodie was convoluted in origin and specifically pointed out for conversation Kelsey had with Arnold about how the P-38s of 1st FG were flown to England in July 1942.

From what I remember the issue of drop-tanks in general was that, for escort missions, they figured that pilots would just punch them off and sacrifice all the range. The fact is that the use of fuel from shortly after takeoff to cruise altitude is a substantial amount of gas. With no change of internal fuel during that period, you would get some range benefit even if you punched it off at the top of the climb. Then around 1939, I'd almost swear there was a concern of it being a fire-hazard and, I do remember looking at a gun-cam shot of a German fighter getting shot in the drop-tank: The tank exploded, one wing came off, and the aircraft did a remarkable roll-rate (uncontrollably, of course).

As to the Mustang I and IA. True no provision for combat or external ferry tanks - but early 1941 NAA developed an auxiliary fuel cell housed in the gun bay 0f 18 gal enabling a 1500 mi ferry (or about a 500 mi combat radius with 2x50 cal guns in Mk I and camera). The P-51-NA had the same provision but USAAF never used it as removing 4x20mm eliminated all armament.

I honestly thought the 4 x 20mm arrangement was something that was solely a British thing. I thought the P-51's originally had 6 x 0.50 (2 x nose + 4 x wings).

He was talking about why the Daimler-Benz was inverted, and had listed all the usual things people say in his video, I gave him a list that was written by Wolfram Eisenlohr, who was in charge of German aero engine development from 1938 to 1944. He wasnt very interested, that was more an attempt at a helpful addition than an "error" as such.

I can sort of understand that, if you're trying to make a video of suitable length. That said, I would be interested in such a thing.

He then made a fairly big error in his P51 performance video, which claimed that the laminar flow wing was basically a legend which had built up and wasnt really very important and didnt work nearly as well as people thought it did. I mentioned 3 archive reports I had which stated the opposite (one was a Supermarine report, the other two were German windtunnel tests of the P51).

I was under the impression that it did produce considerable reduction in drag, though it didn't produce a flow that was perfectly laminar (or at least, as laminar as desired) because of limits in manufacturing tolerances, paint-jobs, and dirt.

 

[Marshall_Stack]

He was talking about why the Daimler-Benz was inverted, and had listed all the usual things people say in his video, I gave him a list that was written by Wolfram Eisenlohr, who was in charge of German aero engine development from 1938 to 1944. He wasnt very interested, that was more an attempt at a helpful addition than an "error" as such.

He then made a fairly big error in his P51 performance video, which claimed that the laminar flow wing was basically a legend which had built up and wasnt really very important and didnt work nearly as well as people thought it did. I mentioned 3 archive reports I had which stated the opposite (one was a Supermarine report, the other two were German windtunnel tests of the P51). He made it clear that he was perfectly happy and didnt want to alter anything. So there you go.

Why was the DB engine inverted?

 

[SaparotRob]

I assume we've all read this and are familiar with it:

Development of the Long Range Escort Fighter

https://www.afhra.af.mil/Portals/16/documents/Studies/101-150/AFD-090529-044.pdf

See page 46 onward for a discussion of external tanks and initial refusal for these.

I am now.

 

[Reluctant Poster]

Well, the Mustang MkI/IA had a 1000 mile range on internal fuel alone, and given their use of the airplane, which was not for long range escort, that was more than enough and verged on twice the range of a Spitfire.

Were the paper tanks self-sealing?

Drop tanks in general were not self sealing

 

[pbehn]

Why was the DB engine inverted?

Why not? What is "inverted". In aero engines a huge number were rotary or radial. Some are horizontally opposed today. The convention of V engines being with cylinders pointing up comes from the car industry and modern times in the 1930s there were no such conventions.

 

[MIflyer]

I did not think that drop tanks were self sealing but there was a distinction being made between ferry tanks and combat drop tanks.

The P-39 could carry a 200 gal ferry tank as well, and I wonder if there was any relationship between it and the 200 gal P-47 tank. The picture is of a P-400 in England equipped to deploy to North Africa.

 

[Zipper730]

R RCAFson

From the document I found a passage on page 9

...."During the twenties only a few innovations were added to
the general escort tactics used in the first World War.
Pursuits were to assist any bomber forced to drop behind the
formation and to prevent concentration of superior enemy forces
against any part of the friendly formation. The basic tenets
of pursuit tactics placed escort under the classification of
"special missions," and through pursuit and bombardment manuals
discussed escprt, no new theories on its used were developed
for many years. Airmen regarded escort as a legitimate
function for pursuit, but found no plane that could provide
it.
.....Most fliers considered the multiplace or two-place type as
ideal for escort since they believed its greater defensive
firepower was advantageous in missions that were lacking in
support."

I don't understand what that means. Lacking in support? Do they mean numerical support -- like they don't have enough fighters?

 

[gjs238]

R RCAFson

From the document I found a passage on page 9

...."During the twenties only a few innovations were added to
the general escort tactics used in the first World War.
Pursuits were to assist any bomber forced to drop behind the
formation and to prevent concentration of superior enemy forces
against any part of the friendly formation. The basic tenets
of pursuit tactics placed escort under the classification of
"special missions," and through pursuit and bombardment manuals
discussed escprt, no new theories on its used were developed
for many years. Airmen regarded escort as a legitimate
function for pursuit, but found no plane that could provide
it.
.....Most fliers considered the multiplace or two-place type as
ideal for escort since they believed its greater defensive
firepower was advantageous in missions that were lacking in
support."

I don't understand what that means. Lacking in support? Do they mean numerical support -- like they don't have enough fighters?

The way I interpret it is that ideally, a bomber formation provides mutual support.
A "bomber forced to drop behind the formation" loses such mutual support, so the "greater defensive firepower" of the "multiplace or two-place type" is a way to mitigate that.

 

[Zipper730]

The way I interpret it is that ideally, a bomber formation provides mutual support.

So, the idea might have meant in cases where the bombers didn't have sufficient overlapping firepower -- the twin-seat fighter could add some extra firepower to the equation?

 

[ThomasP]

Hey MIflyer:

re: "The P-39 could carry a 200 gal ferry tank as well, and I wonder if there was any relationship between it and the 200 gal P-47 tank."

I remembered building Col. Gabreski's P-47 when I was a kid, the Monogram(?) model had the flat steel 200 USgal DT. From what I can see in the P-400 picture it is the same type of DT.

 

[ThomasP]

re the question of self-sealing DTs (SSDT).

There were several SSDT used by the US and UK in WWII.

For the UK there was at least one 30 Impgal slipper "combatable" SSDT used by the Spitfire (starting with the Mk V) and Seafire. There was also a 45 Impgal version (though maybe not used during the war?) All normal maneuvers could be carried out with these tanks, full or empty.

For the US there was at least one version of the USN 150 USgal DT that was "combatable" and self-sealing. I have run across documents (including a couple of the SACs and Pilot's Manuals) that mention the F4U often carried one of them on an inner wing station during the late-war period. There are also some photos floating around on the internet somewhere. As with the UK "combatable" SSDT, all normal maneuvers could be carried out with these tanks, full or empty.

I have read that the F6F also used this 150 USgal SSDT on the centerline, but I have not been able to find any detailed information or photos.