History Friday — MacArthur’s Fighter Drop Tanks

One of the key technologies for developing air superiority in World War II was the fighter auxiliary ‘drop’ fuel tanks. They made deep penetration, fighter escorted, heavy bomber raids possible. Those raids forced Axis fighters to fight more numerous and increasingly better American fighters at a disadvantage, allowing the June 6th 1944 Normandy D-Day landings in Europe under Allied air superiority. For reasons having to do with both intra-service and inter-service politics, technical reasons, training and doctrine, plus plain good luck, MacArthur’s South West Pacific Area (SWPA) theater had such drop tanks in wide service on P-38 fighters during the Battle of the Bismarck Sea (2–4 March 1943), and on P-47’s during June-August 1943. Meanwhile, several months later and 1/2 a world away on the 14 Oct 1943, during the Schweinfurt–Regensburg mission over Southern Germany, the B-17’s of the 8th Air Force were unescorted because their P-38’s and P-47’s lacked drop tanks. This lack caused 20% of the attacking force — 60 B-17’s, and 600 airmen — to be lost.

Auxiliary ‘drop’ fuel tanks weren’t secret. They were common to most American fighters both Navy and Army in the early to mid 1930’s. Nor were they unknown around the world, as the Germans demonstrated in them in Spain early in 1939 (and forgot them for the Battle of Britain in 1940). They were also standard for the Imperial Japanese Navy (IJN) and were responsible — along with “long of lean” fuel control techniques — for the A6M3 Zero’s incredible range in 1941. Yet by the time of Schweinfurt–Regensburg mission, fighter “drop tanks” were unavailable for the 8th Air Force in England. The USAF did a lot to gloss this fact over in the post war narrative, but modern internet search engines will let you see the real facts from declassified documents hiding behind their self-serving unclassified institutional histories.

The 165 Gallon Lockheed Drop Tank in Front of a P-38 Lightning Fighter dated Nov 1943
A 165 Gallon Lockheed Drop Tank in front of a P-38 Lightning Fighter


Development of the Long–Range Escort Fighter.
USAF Historical Study No. 136.
by Bernard Boylan,
USAF Historical Division, Research Studies Institute, Air University,
September 1955

Page 46

In February, 1939, Curtiss-Wright suggested to the Air Corps that it might be interested in testing a 52-gallon tank which could be mounted on the bomb rack of a P-36C. The company offered to build such a tank for experimental purposes and to provide the connection with the main tank. The Materiel Command accepted the offer in March, but in April OCAC (Note – Officer Commanding, Air Corps) questioned use of an external tank because of the fire hazard. The plea of Materiel command that the tank was only experimental was not overruled at first, but in May the Chief of the Air Corps directed that no tactical plane be equipped with a droppable fuel tank.l75



“Drop Tanks
Adding external fuel tanks to existing pursuit aircraft seemed like a logical solution to extending pursuit range. Making the tanks dropable in flight preserved maneuverability and performance when required for combat. Experiments with dropable fuel tanks had been conducted throughout the 1920’s and 1930’s. The greatest concern about drop tanks was the hazard of fire. In February 1939, Curtiss–Wright wanted to test a 52–gallon tank mounted on the bomb rack of a P–36C, but the “Chief of the Air Corps directed that no tactical plane be equipped with a dropable fuel tank” because of the potential for fires.18”

The Air Corps Chief of Staff in February 1939 was General Henry H. “Hap” Arnold. Arnold, like the rest of the US Army Air Force (USAAF) Heavy Bomber Clique saw longer range “Pursuit” as a threat to their mythic uber-bomber budget and more importantly the B-17’s potential to further Air Corps institutional independence, first as the US Army Air Force (B-17) and later as the US Air Force (B-29 plus A-bomb). During the mid-1930’s “Long of Lean” fuel control techniques for extending range were dropped from non-heavy bomber training courses. It took Charles Lindberg’s visit to the SWPA in 1944 to re-introduce the technique to USAAF Fighter pilots. Similar combat prohibitions for the use of internal ferry tanks on the medium bombers like the B-25 and B-26, that matched the range of B-17 heavy bombers in range of action and could still deliver bombs with external racks, were also put into place under Arnold.

While early versions of the P-38, P-39 and P-40 were proscribed from having auxiliary drop fuel tanks “because they might be used inappropriately”. These drop tanks were still offered to other customers by American aircraft manufacturers. The USN insisting their aircraft all have that capability. Point in fact the 165 gallon standard P-38 drop tank pictured above was developed for the Lockheed PV-1, called the Hudson by the British, which was the US Navy version of the Lockheed Ventura twin engine commercial transport. This is why successful drop tank designs were available when the USAAF Bomber Clique Generals finally discovered how desperately they were needed after the Schweinfurt–Regensburg mission.

The reason that MacArthur got the drop tanks first was a combination of luck meeting opportunity in the form of General George Kenney. Kenney was “the great innovator”. He was a technical trouble shooter for General Henry H. “Hap” Arnold, who was not a member of the Heavy Bomber Clique. Kenney was from the pre-war “Attack School”, which like the Heavy Bomber and Pursuit “schools” was established by Gen. Billy Mitchell after World War 1. Kenney did not hold the organizational prejudices of the Heavy Bomber Clique, had been heavily involved with the development of the P-38, and he took steps upon arrival in Australia in 1942 to extend the range of American fighters to match that of the drop tank using A6M3 Zero.

The following passages are from Kenney’s memoirs published in book form as “General Kenney Reports”

page 66
August-September 1942

I know what he meant. He was right. We were not going to make hits until we could keep those bullets out of the bombardier’s cockpit. That new vitamin he wanted was fighter cover. We didn’t guess very well when we designed our fighters with insufficient range to do the job in the Pacific where distance was the main commodity. As soon as I could get those P-38s with their extra range and maybe add some more with droppable tanks hung under the wings, that kid and the rest of them would get their new vitamins.

Page 73
August-September 1942

Twenty-five P-38s, the first of the fifty promised me by General Arnold, arrived by boat at Brisbane. I sent word to Connell to come north from Melbourne, take charge of setting them up, and work twenty-four hours a day on the job. Also to give the Australian sheet-metal industry a contract to make about 10,000 150-gallon droppable gas tanks to hang under the wings so that we could extend the range.

Page 264
June-August, 1943

I then went out to Eagle Farms, where the erection was to be done, and found that no droppable fuel tanks had come with the P-47s. Without the extra gas carried in these tanks, the P-47 did not have enough range to get into the war. I wired Arnold to send me some right away, by air if possible. About a week later we received two samples. Neither held enough fuel, they both required too many alterations to install, and they both were difficult to release in an emergency. We designed and built one of our own in two days. It tested satisfactorily from every angle and could be installed in a matter of minutes without making any changes in the airplane. I put the Ford Company of Australia to work making them. We had solved that problem but it would be another month before we could use the P-47s in combat.

This later DTIC paper adds the following information on the P-47 in the SWPA —

MacArthur’s Airman: General George C. Kenney and the Air War in the Southwest Pacific Theater in World War II
page 280

When the P-47s finally arrived in Australia they did not have droppable external fuel tanks to extend their range. Without those they could not fly far enough to accomplish any missions in the theater. According to Kenney, “this airplane must have extra gas to go anywhere.16 Although a drop tank had been developed in the United States, Kenney thought it “junk” and ordered a prototype 200 gallon tank constructed locally and then contracted with Ford of Australia for mass production. 17 Kenney also suggested that the radio equipment be moved from behind the pilot and the compartment then converted into a forty-gallon fuel tank. 18

It was the P-47, with British made drop tanks, during Operation Point Blank that made Normandy possible. The P-47C was designed to use a 200 gallon belly tank from the get go — the tank Kenney thought was junk — when it was ordered back in late ’41. The 75, 125, 150 and 165 gallon drop tanks for the USN were already standard issue. The P-38’s in England got its 165 gallon drop tanks in Feb 1944 letting P-38’s fly to Berlin and back…to no great effect due to 8th Air Force doctrinal problems.

And it was Lockheed P-38, Curtis-Wright P-40, Grumman F4F’s and Vought F4U’s with Navy and Australian made drop tanks that bled out the IJAAF and IJNAF units flying from Rabaul.

This was in spite of and not because of USAAF Bombardment clique leadership. To quote the Australian Airpower Expert Carlo Dr Carlo Kopp, Associate Fellow AIAA, Senior Member IEEE, PEng and Co-founder, Air Power Australia: http://www.ausairpower.net/

The heavy bombers did inflict the critical attrition on the production base and POL. But they did so only once they were properly supported by escorts. Air power performs best when operated as an integrated whole. The ideologues tend not to accept this. Yes the historical record is unambiguous.

(The sad story of the RAF fighter’s suffering from a lack of drop tanks through the first half of the war, when all American manufacturers could have supplied designs and fixtures, is too embarrassing to detail.)

While Kenney’s other acts of brilliance, like the improvised A-20s and B-25s with the 50 cal gun batteries in the nose, the parachute bomblets for airfield attacks, and skip bombing tactics are all clebrated in USAF institutional histories. It was the example of Kenney’s drop tanks in the SWPA, and the failure of the unescorted heavy bombers during Schweinfurt–Regensburg mission that finally resulted in the command and doctrinal changes to get drop tanks to USAAF fighters for Operation Point Blank, and the achievement of air superiority for D-Day at Normandy.

And now you know the truth behind another “MacArthur narrative.”

17 thoughts on “History Friday — MacArthur’s Fighter Drop Tanks”

  1. It’s always been odd to me about how “government” competition is always non-productive, while non-governmental competition leads to rapid improvements and design developments.

    It seems odd that inter-service rivalries don’t produce positive results.

    Perhaps this is why pro-government types fail to grasp the benefits of free markets and competition. There’s something inherent in the mindset of most government types possess that stifles the positive effects…

  2. Remember, even before the above events, how the navy and the army were so inimical to everything Billy Mitchell came up with — even AFTER it was shown remarkably effective in practice.

    There was, IIRC, a similar battle between the nuclear bombers and the nuclear submarines, and the only reason the nuclear subs continued to do as well as they did was the political talents of Rickover.

  3. Bill,

    The Schweinfurt–Regensburg mission was where the Luftwaffe put together the complete heavy rocket fighter (ME-110) and lighter Me-109/FW190 large formation attacks that could destroy any bomber combat box formation, no matter the size, that lacked fighter escorts through out the entire mission.

    Drop tanks were the technological glue that allowed an offensive aerial combined arms team to develop.

    Only large numbers of heavy bombers could deliver the payload to damage a target badly enough to make enemy fighter to come up and fight.

    Only fighter escorts could break up enemy fighter formations before they could organize an attack large enough to break bomber “combat box” formations.

    The fighter penetration missions — organized in shifts — to cover the bomber formations required long range radar, VHF band frequency modulated radio and radio intercept stations to track both our own aircraft and enemy fighter reaction to get the penetrating fighters to shield the bomber streams.

    The Japanese lack of good radar and aircraft radios meant they could not develop the large aerial combined arms formations without very skilled pilots rehearsing together for months. Something they lost through attrition in late 1942, thanks in large part to MacArthur’s Australian Ford made drop tanks.

  4. VXXC,

    The Safety people in the US Army Air Corps were only as powerful as the Bomber Clique needed them to be in order to achieve dominance over the “pursuit” and ‘attack” factions pre-war.

  5. Note — There have been several minor edits and link activations to include a link to an article Charles Lindberg’s role in extending fighter range in the SWPA via “Long of Lean” flight control techniques.

    Check them out.

  6. >So, the reason for the Mustang’s success at stopping the hemorrhaging of
    >bomber loses in Germany was the drop tanks?

    No, to be more specific, it was insufficient by itself. Carlo Kopp’s article at the link below goes into this quite extensively —

    Der Gabelschwanz Teufel
    Assessing the Lockheed P-38 Lightning
    Technical Report APA-TR-2010-1201

    by Dr Carlo Kopp, AFAIAA, SMIEEE, PEng

    December, 2010
    Updated April, 2012


    This passage is from the link above —

    Capt. Heiden makes some further interesting observations.

    “The P-51 was a new airplane and we were eager to fly it and were happy with it. It was so easy and comfortable to fly. The P-38 had kept us on our toes and constantly busy–far more critical to fly. You never could relax with it. We were disappointed with the 51’s rate of climb and concerned with the reverse stick, especially if fuel was in the fuselage tank, the rash of rough engines from fouled plugs, and cracked heads which dumped the coolant. With the 38 you could be at altitude before landfall over the continent, but with the 51 you still had a lot of climbing yet to do. The 38 was an interceptor and if both engines (were healthy), you could outclimb any other airplane, and that’s what wins dog fights. When you are in a dog fight below tree tops, it is way more comfortable in a 38 with its power and stall characteristics and, for that matter at any altitude.”

    To summarise the performance of the P-38 in the 8th AF, Capt Heiden notes:

    “Aug 43, 8thAF has retrieved some Bomber Gps and has several original Spitfire/P-47 FGs. Two P-38 FGs, 1-P-51 FG that will not be operational till late Oct and have to workout tactics and maintenance problems, which all are severe. Highly inadequate supply of A/C.”

    “Nov. 43, P-38Hs and P-51Bs beginning ops, find themselves in a climate environment none had experienced before and a superior opponent with 10 times the numbers. Forced to take the bombers to, over and withdraw them. Lucky to get half of what they had to the target after aborts/early returns. Sometimes as few as four fighters made it to target under attack continuously going and coming. Five minutes of METO power was planned into the profile. Meaning that if you fought over five minutes you wouldn’t make it home. Remember, you were being bounced continuously.”

    “Feb 11, 44, 357thFG goes on Ops (P-51). 4thFG converts to P-51s. 2-weeks later and other groups are converting by end of Feb. Now fighter groups don’t have to go the whole to, over, and from target. The escort is now Penetration, Target, and Withdrawal, each leg is assigned to only one FG. and many operational problems are being resolved. Internal fuel on P-38s has been greatly increased with Wing and Leading edge tanks. P-47s are starting to get external fuel tanks.”

    “The last half of 43 brought horrendous losses, had forced German manufacturing underground and had forced Germany to go to synthetic oil. This had increased the cost of war exponentially to the Germans.”

    “Feb 44 we went back to Schwienfurt with acceptable loses. March 3rd the 20th & 55thFGs went to Berlin–Bombers were recalled. March, April, and May brought vicious battles, often with heavy loses. However, Germany were throwing their valuable flight instructors and 100hr students in to the battle. The Luftwaffe was at last starting to die.”

    “The 8th was, at last, being flooded with Mustangs and well trained pilots. The Mustang was a delight to fly, easier to maintain cheaper to build and train pilots for, and had long legs. In those respects you can rightfully call it better, but it could not do anything better than a P-38J-25 or L. Just remember who took the war to the enemy and held on under inconceivable odds. Enough of the crap.”

  7. I read somewhere that the early drop tanks in Europe were aluminum. Turns out the Germans would salvage the dropped drop tanks and recycle the precious metal.

    Once we learned that, we changed the design to plywood.

    Reminds me of the Jimmy Buffet song where he notes that house trailers once “looked better as beer cans.”

  8. Whitehall,


    The USAAF 8th Air Force operations research staff officers like Robert McNamara thought that. Which is why the 8th Fighter Command issued the cardboard drop tank contracts.

    It turns out when the OSS went to see if it was so, they found out the Germans thought it was too much work for too little return and did not bother.

    Shot down _bombers_ were a different matter.

    In the mean time, the P-47’s were stuck with drop tanks that when they got soaked with fuel, failed to detach properly. This happened regularly with NW European weather.

    When the OSS feed back came in, the cardboard drop tank contracts were quickly and quietly cancelled.

  9. Thanks very much for the link on the P38. There is much there I had never seen. You come up with great stuff.

  10. Carl,

    Thanks, your feedback is appreciated.


    Dr. Carlo Kopp is who you should thank. He writes good stuff.

  11. Great write up!

    RE: 165 gallon drop tank photo in front of P-38.

    It looks to me as if the Army guys are making off with one of the early USN Blue Gray/Gray Ventura tanks. The colors sure don’t match the Green/Gray P-38. Does anyone have a idea where this photo was taken?

    On another note I am looking for a copy of an article that appeared in a periodical circa 42-44. I found it in a readers guide years ago but lost my note. It was about how Lockheed constructed these steel wing tanks. If anyone knows about this article I would certainly appreciate a note.

    Thanks, Len

  12. >>the early USN Blue Gray/Gray Ventura tanks.
    >>The colors sure don’t match the Green/Gray P-38

    I got the photo from a Bellytank racer web post and it listed the photo as happening in 1942. (See link on the subject) I can’t find the direct link because Google now has my post’s version of the photo high on my searches.


    BTW, the Ventura tank and the P-38 tank were the same tank with a different coat of paint. Locheed’s Kelly Johnson designed the P-38 to use the Ventura tank. The USAAF told Locheed not to include it on the early P-38’s just like they did the early P-39’s, P-40’s and P-47’s.

    See also this link regards the tanks on Guadalcanal for the Yamamoto raid —


    The most significant event of Rex Barber’s career, perhaps of his entire life, took place just a short time after he had joined the 339th Squadron – in mid-April 1943. A coded Japanese message was intercepted, telling in precise detail, the planned route and scheduled (0945 hrs) arrival for Admiral Isoroku Yamamoto�s flight to the island of Ballale, just off the coast of Bougainville on the morning of
    18 April, 1943. Because the U.S. had previously broken the secret Japanese codes and could translate their intentions, Major John Mitchell, Commanding Officer of the 339th Fighter Squadron, was selected to plan and lead a flight to intercept and to shoot down Japan’s foremost military leader. Due to the extreme distance involved… more than 425 over-water miles each way, it was determined that only the P-38 would have sufficient range to carry out such a mission, and even then, they would require the large 310 gallon drop-tanks … but the only tanks available on Guadalcanal were the shorter-range 165 gal. models.

    Roger Ames, 12th Fighter Squadron, one of the mission pilots (and a long-time member of the 18th Fighter Wing Assoc.), recalled: “We put in an emergency order for the larger tanks, which had to be flown in during that night, and the crews worked throughout the night installing one each of the 310 and the 165 gallon tanks on every available P-38. We had only 18 flyable P-38s between all of our squadrons, and all were scheduled for the mission, but only 16 made it into the air.”

  13. HI,

    I was wondering if you can tell me where you got the photo of A 165 Gallon Lockheed Drop Tank in front of a P-38 Lightning Fighter as we want to use it for our TV programme? Guy Martin has rode a Triumph vehicle on the Bonneville Salt flats recently and we filmed his attempt for a Channel 4 programme, I am just trying to track down the rights holder of this image.


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