A Mustang I running low over the European countryside. The RAF tactical reconnaissance squadrons relied on hedge-hopping and speed to avoid detection, interception, and anti-aircraft fire. The photos they brought back helped shape the D-Day invasion plan.
“When I saw Mustangs over Berlin, I knew the war was lost.”
–Hermann Goering
DROP TANKS, FUEL MANAGEMENT, and a new fighter saved the daylight strategic bombing campaign. Ironically, all three solutions found their way to Europe despite entrenched resistance from the USAAF’s stateside bureaucracy.
Drop tanks—external fuel cells that could be released after the gas inside them had been consumed—had been around for several years. The Germans had them available for their Bf-109s during the Battle of Britain but failed to employ them as well. Basically, what it came down to was this: hanging stuff under a fleet-of-foot fighter made them far less fleet-of-foot, and that was anathema to the fighter purists within the USAAF.
Fortunately, there are always rebels in uniform willing to buck the establishment and do what is right, not what is acceptable or career-friendly. Colonel Cass Hough was one of those brilliant rogues. Before the war, he’d been the CEO of the Daisy Air Rifle Company and had made millions selling BB guns to an entire generation of American kids. He possessed a sharp intellect, courage, and a solid understanding of engineering. As a pilot himself, he also grasped many of the issues facing the combat crews in England.
Designed and built in less than four months, the North American Mustang was the product of a British need for more fighters. Originally, the RAF simply wanted North American to build Curtiss P-40s for it. The management at North American believed they could do better—and they did.
During the war, as the commander of the Eighth Air Force’s Technical Service Section, he watched the bombers come home shot full of holes day after day and began to ponder how he could extend the range of the existing fighters serving in England. The Spitfire was never going to be more than a short-range air superiority weapon. The P-47 was a different story. In 1943, on internal fuel, the Thunderbolt pilots could hang with the bombers for about 230 miles before they had to turn back.
The USAAF took an interest in the new North American design and ordered fighter, reconnaissance, and dive-bomber versions of it.
Hough experimented with existing American ferry tanks at first. He found them lacking in every respect. At altitude, some would not feed properly. Others banged against the underside of the fuselage or wing, even at normal cruising speeds. The lightweight paper tanks tended to leak after only a few hours.
Hough realized he needed a new design. He looked at British auxiliary tanks, then settled on fabricating his own. Since the fighters operated above 20,000 feet most of the time, the tanks had to be pressurized in order to feed properly at such heights. That proved to be a tricky engineering problem. Nevertheless, by May 1943, he and his men developed a steel-fabricated hundred-gallon tank for the P-47. Once approved, the design was contracted to local British firms, but a shortage of sheet metal hampered production through the summer.
Hough looked for another alternative. He began playing around with a British 108-gallon ferry tank made out of paper. With some finesse, his engineers came up with a way to strengthen the tanks so that they could withstand pressurization. The new version went into production in July 1943.
The dive-bomber variant of the Mustang was designated the A-36. It served in the Mediterranean and China-Burma-India theaters.
The Mustang I probably would have been relegated to an aviation history footnote had it not been for Ronald Harker, Rolls-Royce’s chief test pilot. He flew one and realized that if the Allison engine could be replaced with a Rolls-Royce Merlin, the Mustang’s performance and range would be significantly enhanced. He advocated such an experiment despite red tape and bureaucratic opposition. The result was a hybrid Anglo-American effort that would play a significant part in winning the war.
A shortage of drop tanks marred the summer and fall. In desperation, some four thousand seventy-five-gallon cells designed for the P-39 arrived in England. The fighter groups put them to good use until the larger tanks became available in sufficient numbers. Through the fall, larger tanks went into production, and the P-47 was modified to be able to carry them under the wings as well as the fuselage centerline.
A P-51A at a depot in England. It would not be until the marriage between American airframe and British engine that the Mustang became a world-class fighter. Even then, its significance to the strategic bombing campaign was totally missed by the Eighth Air Force’s leadership until Jimmy Doolittle arrived to replace Eaker in early 1944.
By early 1944, the Thunderbolt units could carry aloft an extra three hundred gallons of fuel under their wings. This gave the Jug pilots the legs to stretch deep into the Third Reich. Given that the P-47 composed the majority of the VIII Fighter Command’s available strength, extending their radius of action played the single most important role in winning the air war in 1944.
At the same time the tanks came into widespread use, the USAAF underwent a mini-revolution in fuel management, thanks in part to Charles Lindbergh. The famed aviator traveled all over the world, showing American pilots that if they leaned out their fuel mixtures, raised their manifold pressure in their engines, and slowed the revolutions per minute their propellers made, they could significantly extend their radius of action. The P-38 pilots went from being able to spend four or five hours in the air to eight to ten—longer by war’s end with the addition of larger external tanks. Inevitably, the Jug pilot’s of the 56th Fighter Group made it all the way to Berlin and back on more than one occasion before the war ended in May 1945.
Drop tanks and fuel management never received the press they deserved for saving the daylight strategic bombing campaign. Instead, the Mustang absorbed most of that credit. Born from a British design requirement, turned into the USAAF’s only dedicated single-seat dive bomber used during the war, the Mustang eventually morphed into history’s ultimate long-range air superiority weapon.
An early Mustang undergoing cold-weather testing in Alaska.
In 1940, the British came to the United States on an aviation shopping spree. Desperate for aircraft to use against the Germans and knowing that their own production capacity was very limited, the British Purchasing Commission traveled around America offering contracts for such planes as the Curtiss P-40 and the Lockheed Hudson. When the Brits reached North American Aviation, they asked the company to build P-40s under license for the RAF. That did not appeal to North American’s management, and instead the company offered to build a totally new fighter design that incorporated all the hard-won lessons learned in Europe so far. What’s more, they promised to build the prototype in 120 days.
The British agreed and the race was on. North American put the project in full gear and made everyone work sixteen hour days, seven days a week. The effort paid off: after 117 days, the prototype rolled out of the factory. Dubbed the XNA-73, the new fighter used a 1,100-horsepower Allison engine as its power plant. Test flights encouraged the British so much that they ordered it into production. The first Mustang I, as the RAF called it, took flight in April 1941. At low altitudes, it could beat anything in the air, including the Spitfire. Below 10,000 feet, it could best a Spitfire’s top speed by thirty-five miles an hour.
Further flight evaluations in 1941 and early 1942, however, demonstrated a serious lack of power above 15,000 feet. The Allison engine without a supercharger just could not perform at altitude. Fighter Command rejected the new aircraft, and it was sent to the purgatory of army cooperation and reconnaissance squadrons, where they went into operational service starting in the spring of 1942.
An A-36 over Mount Vesuvius. The A-36 filled the dive-bombing role quite well, though by the time it arrived such tactics had fallen out of favor within the USAAF.
The USAAF took notice of the new design as well. When North American adapted the Mustang to the dive bombing role, the Army ordered five hundred of them. Called the A-36 Invader, they would see combat in the Mediterranean with both ground attack units and reconnaissance squadrons.
P-51A Mustangs served in combat in the China-Burma-India Theater, where they gained a reputation as excellent fighter-bombers.
The 31st Fighter Group left England in 1942 to take part in the North African campaign. The outfit never returned to the Eighth Air Force. Instead, it joined the XIV Fighter Command when it was activated at the end of 1943. Re-equipped with Mustangs, the 31st provided long-range escort for the Liberators and Forts of the XIV for the rest of the war.
Later, the USAAF ordered a fighter variant as well, which originally was called the P-51A Apache. They saw service in the China-Burma-India Theater and the Mediterranean.
In April 1942, Ronald Harker, the chief test pilot for Britain’s Rolls-Royce’s aircraft engine department, flew to Duxford and climbed into a Mustang I’s cockpit for the first time. A man of vision and great energy, he quickly saw the Mustang’s potential. He noted that the new plane could carry three times the fuel the Spitfire could, and then he wondered what might happen if the airframe was mated to a Rolls-Royce Merlin engine. The Merlins tended to sip less fuel than the gas-hungry Allison, and the idea of such a union intrigued him enough that he went to his superiors to advocate for such an experiment.
He came up against a lot of opposition and RAF disinterest in the American design, but he stuck with his idea until he finally got approval. The test showed it to be a match made in heaven, perhaps the best example of trans-Atlantic technical cross-pollination during the entire war. The new Merlin-powered aircraft excited everyone. Back in the States, North American saw it as a chance to save the design, and the high-altitude, long-range performance the new engine offered gave it considerable potential. Hap Arnold quickly grasped that and ordered over two thousand in late 1942.
The P-51B quickly showed its mastery over the Bf-109 and Fw-190A. Initially armed with four .50-caliber machine guns, the new fighter did suffer from frequent weapon jams. It only took a few months to fix that problem, and after that the Mustang came into its own just in time to help deliver the knock-out blow to the Luftwaffe.
To keep pace with the airframe’s production, Packard was given a contract to build the Merlin under license in the United States. By November 1942 the first Packard/Merlin P-51 rolled off the assembly line at North American’s Inglewood plant in Southern California.
Known as the P-51B Mustang, the aircraft replaced the 354th Fighter Group’s aging P-39 Airacobras during the final phases of that outfit’s pre-deployment work up in the United States. In December 1943, the “Pioneer Mustangs” reached England and joined, ironically, the Ninth Air Force, which was a dedicated tactical aviation organization.
Max Lamb, one of the 354th Fighter Group’s aces, sits in the cockpit of his P-51. The Pioneer Mustangs produced no fewer than forty-five aces during its amazing combat career.
It didn’t matter. The 354th Fighter Group began flying long-range escort missions with the Eighth Air Force almost immediately. When married to long-range drop tanks, the new Mustangs could range the length and breadth of the Third Reich. No longer would the Forts and Libs be left alone to face hordes of Luftwaffe interceptors. The only thing the Americans needed now was more Mustang groups. Through the first months of 1944, new ones arrived nearly every week. The famed 4th Fighter Group turned in their P-47s and took delivery of factory-fresh Mustangs. Most of its pilots had served with the Eagle Squadrons in the RAF and had loved their graceful Spitfires and never liked their heavier, less maneuverable Jugs. But when they climbed into their new Mustangs, they knew they’d been given a true thoroughbred—one that would take them to Berlin and back.
Lieutenant William Groceclose climbs out of his 4th Fighter Group P-51. The 4th earned fame as the top-scoring Eighth Air Force unit during the war, accounting for over a thousand Luftwaffe aircraft on the ground and in the air.
Armorers prepare to load .50-caliber ammunition into the wings of a 4th Fighter Group P-51. The D model carried six guns instead of the earlier variants’ four.
The “Bottisham Four”—a legendary quartet of 361st Fighter Group P-51 Mustangs led by Thomas Christian’s Lou IV. Christian, a West Point graduate, was only twenty-eight years old when he was killed in August 1944. This photo was part of a series shot from a 91st Bomb Group B-17 on July 26, 1944.
Big Friend, Little Friend. The Mustang saved countless bomber crews and ensured the success of the 1944 strategic bombing campaign.
Lieutenant Colonel Thomas Christian flies over England in August 1944. Christian lived only a few more days after this photo was taken. He was killed in combat on August 12, 1944.
Don Blakeslee, legendary fighter leader, tactician, and ace, commanded the 4th Fighter Group. He had flown with one of the RAF’s Eagle Squadrons prior to the U.S. entry in the war, and in the years that followed he flew more missions and accumulated more combat hours than just about any other fighter pilot in the European Theater.
A formation of 361st Fighter Group P-51D Mustangs in flight over England late in the war. The D model arrived in theater later in 1944 sporting a new canopy that provided much better all-round visibility than did the B and C razorback versions.
The end of 1943 saw the confluence of these developments reach England just in the nick of time to save the daylight bombing campaign. It was true serendipity and set the stage for the massive air battles that determined the fate of the Third Reich in the ensuing six months. Without the fuel tanks, without the Mustang, the Eighth Air Force’s campaign would have remained dead in the water. Now, as 1944 began, the Eighth would return to the skies over Germany with renewed energy, a new mission, and fighter escort needed to get the job done.
361st Fighter Squadron P-51 ace Vernon Richards. He flew a Mustang named Tika IV. The 361st, 352nd, and 4th Fighter Groups were among the leading P-51 outfits in the Eighth Air Force.
