COMPARING APPLES WITH LEMONS

“Let’s fight till six, and then have dinner”, said Tweedledum.

Between August and December 1941, two XP-51 Mustang examples had been delivered to the U.S. Army for evaluation at Wright Field, Ohio. Both aircraft were equipped with the Allison V-1710 engine and armed with eight .50-caliber and two .30-caliber machine guns. Both had a 170-gallon fuel capacity yielding a range of 750 miles at a 325 mph cruising speed. The manufacturer guaranteed top speed of 375 mph would be exceeded in the testing.

On October 21st North American test pilot Bob Chilton arrived at Wright Field to fly examples of the Spitfire V and Hurricane II to compare their performance and flight characteristics with those of the Mustang. He immediately noticed that the XP-51s had only one flight hour in their logbooks and learned that, as the ’51s were not under an Army production contract, they were not considered as important as the other fighter aircraft then at Wright for testing and evaluation, the Republic P-47 and the Curtiss P-60, both scheduled for production in 1942. In fact, when the Army Air Force Pursuit Board met in October of that year to debate the futures of eight production and eighteen experimental pursuit aircraft, the XP-51 was not even among the planes considered.

The Army focused on a wide range of fighter aircraft concepts, advancing several of them to various stages of preliminary development. These included the twin-boomed Vultee XP-54, promoted as a 510 mph sensation; the swept- wing, canard-equipped Curtiss-Wright XP-55; and the strange and tailless Northrop XP-56. Experimental prototypes also were ordered for the Curtiss-Wright P-60, P-62, and the huge XP-71. Work progressed on the XP-39E, the XP-59, and the XP-63 of Bell Aircraft, Republic’s XP-47E and XP-69, while Lockheed concentrated on their XP-49 and XP-58 twin-engined aircraft, and McDonnell on their XP-67. Little wonder there was no room on the table for North American’s P-51. Of all the aircraft discussed by the Army Pursuit Board that October, only the Northrop P-61 Black Widow night fighter would ever see combat.

Crucially for Army planners, they had only two pursuit/ fighter types then in quantity production for the service, the Bell P-39D Airacobra and the Curtiss-Wright P-40E Warhawk, neither of which was capable of the kind of performance they needed. Their best hope for a successful high-altitude air-superiority fighter lay in the twin-engined, turbo-supercharged Lockheed P-38 Lightning and the Republic P-47 Thunderbolt, should one or both live up to their touted capabilities.

By December 1941, when naval and air forces of the Japanese Empire had attacked the battleships of the U.S. Pacific Fleet at Pearl Harbor, Hawaii, a new urgency prevailed among those Army planners. The best available fighter aircraft were suddenly essential to the rapidly growing American war requirement. The Americans then began to commandeer Lightnings and Airacobras destined for shipment abroad, for their own use, while the flow of Kittyhawks (the export version of the P-40E) and Mustangs to Britain continued unabated.

Testing of the XP-51, meanwhile, was producing some fascinating information that even the previously disinterested U.S. Army Air Corps could not afford to ignore. NACA test pilots found that the plane’s laminar flow airfoil was extremely efficient “reducing peak airflow velocities over the wing; postponing and minimizing the ‘compressibility effects’ then troubling the other fighters of the time. Motion picture photography was used to show the effects of increasing dive speed on the aircraft and test-pilot safety was improved in the course of the flight-test programme. The results of roll rate and dive recovery tests were impressive and the Army soon expressed genuine interest in the Mustang, in the belief that it now had a priority need for “a suitable dive-bomber, low-altitude attack fighter”. It asked North American to create a dive-bomber to be designated A-36 from the Mustang.

A contract was issued to the planemaker for 500 A-36As, to be equipped with external racks capable of carrying a 500-pound bomb or 75-gallon drop tank under each wing, and acceleration-limiting dive brakes. By May 1942, Bob Chilton was flight-testing the new dive brakes and by July he was flying dive-bombing tests. In the same period, he had been flying drag tests of the cannon-equipped lend-lease P-51 for the British. Intrigued, the Army planners now found a pressing need for some of these planes for use in tactical reconnaissance squadrons, and requisitioned the first twenty such aircraft to emerge from the factory in July.

Of the 150 Mustangs in that production batch, 93 went to the Royal Air Force, two were retained by North American for engine experimentation, and the final 35 also went to the Army Air Force. 54 of the Army Mustangs were ultimately modified for photo-reconnaissance and re-designated F-6A. Army Air Force interest in the Mustang was increasing and North American executives decided to develop a pure fighter version of the aeroplane; with an improved engine, all .50-caliber armament, and drop tanks for considerably greater range. This was the NA-99 project, which would lead to a USAAF contract for 1,200 P-51As in August 1942.

Most pilots found the Lockheed P-38 Lightning more difficult to fly than the best single-engined fighters of the day. In northern climates the cockpit could be miserably cold and, in such conditions, the twin supercharged Allison engines were especially temperamental, causing constant problems for the pilots and mechanics of the U.S. Eighth Air Force operating from English bases in WWII. It was not until the late appearance of the P-38L model that improved heating, defrosting, and engine fire extinguishing systems became operational. But by then the Eighth had given up on the P-38 as a primary escort fighter for its long-ranging high altitude bombing missions to German-occupied Europe.

The Lightning faired much better in the warmer climate of the Pacific war theatre, where its two-engine performance and over-ocean capability proved particularly useful. Pilots there appreciated the safety of two engines over long stretches of open sea, the plane’s great speed, rate of climb, payload, and its nose-mounted concentration of firepower.

The Lightning produced a number of notable fighter aces out there including Major Richard Bong, known as the “ace of aces.” Bong finished the war with a total of 40 combat victories and he was a recipient of the Congressional Medal of Honor as well as the Distinguished Service Cross, two Silver Stars, seven Distinguished Flying Crosses and fourteen Air Medals. He admitted that he was actually a poor shot in the air, and had to compensate for his lack of accuracy by getting in dangerously close to the enemy and sometimes flying through the debris of his target aircraft. On one occasion he actually collided with the enemy plane. Bong named his P-38 ‘Marge’ after his fiancé, and carried a large photo of her on the nose of his fighter.

The Lightning proved highly successful for Major Bong, and for the pilots of the 339th Fighter Squadron, 347th Fighter Group, based on the island of Guadalcanal in 1943. On April 14th U.S. Intelligence had learned that Admiral Isoroku Yamamoto, Commander-in-Chief of the Combined Japanese Fleet, was to fly an inspection tour of the Japanese base at Bougainville on April 18th. At the behest of U.S. President Franklin Delano Roosevelt, a mission was quickly planned to ‘get Yamamoto’, using eighteen P-38s with long-range fuel tanks to intercept and attack the admiral’s plane. The American pilots were briefed that they would be going after “an important high-ranking officer”, but were not told who he was. The P-38 pilots flew the 430 miles to the interception point at wave-top height and under radio silence. At 9:34 a.m. they met and engaged Yamamoto’s Mitsubishi G4M ‘Betty’ bomber, a second Betty, and his escort of six A6M Zero fighters. In the encounter, Lt. Rex Barber and Captain Thomas Lanphier each claimed to have downed the bomber carrying Yamamoto, and both were given a half credit for the victory. The action raised morale in the United States and shocked the Japanese.

Of all the fighter planes of the Second World War era, the Lockheed Lightning is certainly among the most fascinating and unusual. In 1937 Clarence Kelly Johnson, the brains behind the Lockheed creative group later called ‘The Skunk Works,’ began the design of the P-38. It was based on a U.S. Army specification calling for an interceptor able to climb to 20,000 feet in six minutes, no small feat in the late 1930s. Johnson’s design group would also create many famous and extraordinarily capable aircraft, including the SR-71 Blackbird spy plane with Mach 3.2 speed and an 85,000-foot service ceiling. But it was the P-38 that sparked his remarkable career and began his reputation as an innovative pioneer in aviation design.

Employing a twin-boom airframe to accommodate two V-1710 12-cylinder Allison engines, Johnson set out to build a fighter unlike anything the Army might have envisioned. He positioned superchargers in the large booms behind the big Allisons to give the plane the required high-altitude performance. He armed it with four .50-caliber machine guns patterned around a cannon in the nose. He gave it a tricycle landing gear, greatly improving the pilot’s forward visibility on the ground. And, in the lovely art deco style of the time, he shaped the Lightning in a streamlined elegance in respect of the aviation adage, if it looks right it will probably fly right . . . which it did, for the most part. But the Lightning suffered one particularly serious problem known as “compressibility stall”, when the flight controls simply locked up during a high-speed dive. With no known way to overcome the condition, the pilot was forced to bail out. In some instances, the problem became so severe that the entire tail structure of the plane disintegrated.

Kelly Johnson: “I broke an ulcer over compressibility on the P-38 because we flew into a speed range where no one had ever been before, and we had difficulty convincing people that it wasn’t the funny-looking airplane itself, but a fundamental physical problem. We then found out what happened when the Lightning shed its tail, and we worked during the whole war to get fifteen more knots speed out of the P-38. We saw compressibility as a brick wall for a long time. Then we learned how to get through it.”

Unfortunately, compressibility wasn’t the only problem the Lightning had. Its most catastrophic defect was what may be called “asymmetric power”, where one of its two engines would fail on take-off, causing the aircraft to flip over and crash upside-down into the ground. In time a procedure was devised for a pilot to cope with asymmetric power situations. But if he was going to live he had to be quick and skillful. It required him to immediately reduce power on the running engine, promptly feather the propeller on the dead engine, and then gradually increase power to stabilize the plane in flight. It was this problem, and the bad reputation it spawned for the P-38, that preceded the new fighter into war.

The Lightning went to war in the Pacific in August 1942. P-38s opened their accounts that month by downing two Kawanishi H6K “Mavis” flying boats. In that same month a USAAF P-38F joined forces with a Curtiss P-40 to destroy a German Air Force Focke-Wulf Fw 200 raider in the Battle of the Atlantic.

German fighter pilots entering combat with P-38s soon discovered the folly of turning into a head-on attack with the Lockheed plane and its super-concentrated firepower. They were startled too by the Lightning’s zoom climb capability, but soon found that, as a dogfighter, the American plane was not quite the dangerous foe they had feared, except when flown by an exceptionally gifted pilot.

In 1943 the American Eighth Air Force was using P-38s to shepherd its B-17 and B-24 bombers on their deep penetration daylight bombing raids into Europe. The Lightning pilots suffered considerably from the cold on these missions and the P-38s were eventually withdrawn from the escort role. Many of them found a new job in low-altitude reconnaissance work where they proved far more successful.

“Don’t give me a P-39 / With an engine that’s mounted behind / It’ll tumble and roll / And dig a big hole / Don’t give me a P-39.” That verse by an unknown wartime author, sums up the view of many American pilots who trained on the Bell fighter at Tonopah in the Nevada desert during 1943. Bud Anderson, among the greatest of all the American fighter aces wrote: “The P-39 could be tricky. ‘It’ll tumble and spin, and soon auger in’, as one of our drinking songs aptly put it. It had a reputation for tumbling end over end, which hardly inspired the pilots. I saw one do something of the sort, go end over end out of control. Later, I asked some Bell test pilots about it, and they said they had tried every trick in the book to make the plane tumble, and never could do it. But you had to be careful with it, particularly if you were new to it. Things happened quickly. This wasn’t a forgiving friend like the good old AT-6.

“It was a good-looking airplane. If looks counted for anything, it would have been a great airplane. The Russians absolutely loved them, and wound up with most of them. Under 15,000 feet, the P-39, called the Airacobra, was a decent if underpowered performer. But the Airacobra was mincemeat above 15,000 feet, and useless in Western Europe, where virtually all the flying and fighting was at double that altitude . . . but in October of 1942, I was thrilled to be flying it. It was unique, with its engine behind the cockpit, and the propeller drive shaft running between the pilot’s legs. It had a trycycle landing gear, unlike anything in our arsenal except the P-38. And the cockpit was more like a car’s, with a door instead of a swing-up or sliding canopy, and windows that actually rolled up and down with a crank. You could taxi the thing while resting your elbows on the sill, like cruising the boulevard on a Saturday night.”

Was it a tumbler? The experience of 2nd Lt. Harvey Mace, 357th Fighter Group: “It was decided by somebody that a good training exercise would be to have all three squadrons engage in one huge dogfight. We had this big melee going and I was hot on the tail of an opponent when he pulled up into a loop. At the top of the loop, I happened to look to my left just in time to see some poor soul fall into a tumble. I was so distracted laughing that I let my own airspeed fall too low and the P-39 promptly reminded me of my foolishness by snapping into an immediate tumble of my own. The stick jerked out of my hand and all I could do was keep my knees and hands out of the way of the flailing stick until the airplane decided to do something that I could recognize. Finally, the ship stopped tumbling and settled down absolutely straight and level—but with no airspeed showing on the dial. I very carefully took hold of the now quiet stick by two fingers and gently pushed forward to get the nose down. The fact that it responded showed that there had to be some forward motion. I hardly dared breathe as the nose dropped down enough to where the airspeed needle began to creep up the dial. I didn’t do a thing more until I could see 200 mph on the dial. Only then did I re-enter the fray.”

The Bell P-39 Airacobra was the third entry in the Army fighter competition of 1937. It was certainly an oddity with its mid-fuselage engine positioning, its car door entry, and its 37mm nose-mounted cannon. And it was quite a performer, at least as a prototype. With a top speed of 390 mph, it was also capable of climbing to 20,000 feet in just five minutes, a full minute less than the time required in the Army specification.

Fighter pilots of the RAF inherited a number of P-39s from a French contract when France fell to the Germans in the spring of 1940. The British pilots disliked the plane for the way its performance fell away above 20,000 feet, for its rather short range (only 430 miles on internal tankage, 690 miles with drop tanks), and most worryingly, for its tendency to spin and the difficulty in recovering from the condition. The RAF realized that it desperately needed a truly effective high-altitude fighter and quickly abandoned the Airacobra.

American pilots in the Pacific were also unhappy with the unconventional Bell fighter, having the same objections as the British, and finding that they simply could not turn or maneuver with the far more agile Japanese Zero. And the 37mm cannon armament of the Airacobra proved ineffective against the Japanese fighter due to the slow rate of fire of the big weapon and the drooping trajectory of the shells. Many P-39 pilots there hated the plane and requested transfers to P-38 units.

Soviet pilots, on the other hand, were enthusiastic in their praise for the Airacobra. Once they got beyond early problems with the radios and with the aeroplane’s tendency to spin, they liked the low-altitude speed, the strength of the airframe, and the armament which evidently performed well for them. At most medium altitudes over Soviet territory, these fliers achieved significant results against early Bf-109s and Ju-87 Stukas. Five of the ten highest scoring Soviet aces were P-39 pilots. Nearly half of all the P-39s produced were sent to the USSR. The Soviets managed to successfully utilize this aircraft while, for the most part, the Western Allies could not.

When the Anglo-French Purchasing Commission approached North American Aviation, Los Angeles, in February 1940, their aim was to get the planemaker to build Curtiss P-40s for them to use against the Germans in a war the Americans were then only reading about. In the competition that developed around that 1937 U.S. Army specification for a new fighter, Lockheed, Curtiss, and Bell all produced new designs for the plane they believed would be dominant in the next war. The Curtiss entry was the P-40 Warhawk, a 362-mph Allison V-1710-powerered aeroplane with an 850-mile range and an armament of six .50-caliber wing-mounted machine guns.

The rap against the Warhawk was that it was too slow. In fact, its speed matched that of the Spitfire Mk 1a and the Messerschmitt Bf-109E, and surpassed that of the Hawker Hurricane and the Mitsubishi A6M-2 Zero. Also, it was, for its time, a relatively good, competitive machine. And the conservative Army planners wanted a traditional, proven design; not something as radical as the twin-engined P-38 Lightning which, incidentally, was far more complex and more difficult to build than the P-40. Critics of the Warhawk also knocked it for not being as maneuvrable and nimble in combat as the Zero. The Japanese pilots, however, considered the P-40 their most difficult and dangerous oppponent at low to medium altitudes; they most feared the P-38 at high altitudes and most of them thought the Vought F4U Corsair the best all-round fighter they faced.

The Army chose the P-40 from the others in the competition for a new fighter and awarded a production contract to Curtiss-Wright. By 1940 it was active in British and American squadrons, performing well in most respects and impressing its German adversaries more than the Hurricane had done. P-40s were also quite popular export aircraft, serving in the air forces of the USSR, Canada, New Zealand, Egypt, Brazil, China, and Turkey.

The P-40 is best known for its fighting role with the famous Flying Tigers of U.S. Colonel Claire Chennault. This volunteer group operated in China and Burma from December 1941 through July 4th 1942, destroying 297 Japanese aircraft, with another 153 probably destroyed, in their first six months of combat, against a loss of just twelve of their own planes. Much of their success was due to the superior flying and gunnery skills of the U.S. pilots to that of their opposition. They had to be good, both to prevail and because the P-40 was not without shortcomings, which included an inferior turn rate and rate of climb to those of the Zero.

13,738 P-40s had been built by the end of 1944, when other American fighters, including the P-38, P-47, and the P-51, had replaced the Curtiss plane, ushering in a new standard of fighter performance.

Love it or hate it, you had to be impressed by the sheer size and apparent potential of the Republic P-47 Thunderbolt. Nearly as fast as a Mustang, twice as heavy as a Spitfire, with substantial range, armament and payload, the Jug, as it was known, was a big, high achiever wherever it operated. With 15,677 of the planes built, it was the most heavily produced U.S. fighter aircraft of the war, edging out the Mustang (at 15,386), the P-40 (at 15,000), and the P-38 (at 10,037). The performance envelope of the P-47D Thunderbolt included a top speed of 426 mph at 30,000 feet, a range of 1,800 miles on internal fuel, and an armament of eight .50-caliber machine guns and up to 1,500 pounds of bombs.

The big P-47 entered combat in the European Theatre of Operations early in 1943 with units of the Eighth Air Force where it shouldered much of the escort role for the heavy bombers of the command. Until the advent of the P-51 in sufficient numbers to take over the protection of the heavies, the Jugs performed extremely well. One outfit, the 56th Fighter Group, under the command of Colonel Hub Zemke, accounted for 1,006 enemy aircraft shot down against the loss of just 128 P-47s. Zemke’s unit included several of the war’s great aces—Francis Gabreski, Robert S. Johnson, Bud Mahurin, and Zemke himself. The rival 4th Fighter Group, commanded by Colonel Don Blakeslee, also flew the Thunderbolt for a while. But Blakeslee didn’t like the aeroplane and wasn’t shy about expressing his view. When reminded by one his pilots how well the P-47 could dive, Blakeslee remarked: “It ought to dive—it sure as hell can’t climb.”

What most of its pilots did like about the Thunderbolt was its ability to absorb the punishment of enemy fire and survive to bring them safely back to base. As the missions of the Thunderbolt increased in duration, some changes were made to improve the comfort of pilots. The leg room was increased through the employment of folding rudder pedals, the original seat was replaced by an “armchair” type model, and an automatic pilot was added.

In summing up his opinion of the P-47 relative to the Mustang, one Pacific war pilot recalls appreciating that the Thunderbolt could climb higher, to 40,000 feet, and operate comfortably at that altitude where other aircraft tended to stall out. With its eight machine guns to the Mustang’s six, the P-47 had 1/3 more firepower, which he felt made a big difference.

That armament, together with the P-47’s ability to carry and deliver 1,500 pounds of bombs (or up to 2,500 pounds when using water-injection for take-off on a long runway) made the Thunderbolt a formidable fighter-bomber. He also considered it a superb strafer and ground-attack weapon against troop concentrations, ships, trains, airfields, ammunition dumps and anti-aircraft installations. For him it was a first-class fighter, having destroyed nearly 12,000 enemy aircraft in the air and on the ground. In performance terms, he has always been impressed by the Thunderbolt’s dive capability, believing it could outdive the Mustang and every enemy fighter. But it was the key safety factor in operating the Thunderbolt that caused him to favour the heavy Republic fighter over the Mustang—the size and inherent structural integrity of the Jug airframe. If a pilot had to ditch at sea or belly-land his damaged plane, he was quite convinced that the odds of survival favoured the Thunderbolt pilot over his Mustang counterpart. He saw the “scoop” under the Mustang fuselage as a dangerous impediment to safely ditching or bellying in, should that be necessary.

A further safety consideration relates to the Jug having that big, air-cooled radial engine, rather than a liquid-cooled V-12 like the Mustang. A small-caliber strike to the engine or cooling system of the Mustang, particularly on an over-ocean mission, virtually guaranteed you were going to get wet before you got home, if you got home. And that big Thunderbolt radial engine could take substantial punishment from enemy fire and often keep running well enough to get the pilot back to base. He liked the added comfort and roominess of the larger P-47 cockpit and really appreciated it on the very long seven and eight-hour missions he sometimes had to fly. As for ease in flying, he called attention to the very wide, strong landing gear of the P-47. “When you set it down, it was down,” an important consideration on some of the rough, damp and irregular airstrips he had to use.

By the end of 1943, the vastly improved Mustang in the form of the P-51B was in production and on the way to building its reputation in the European air war. The job of these Eighth Air Force P-51s was to escort their ‘Big Friend’ heavy bombers on high-altitude raids deep into Germany. The other best American long-range escort fighter, the P-47D, was limited to a 400-mile combat radius even with a 108-gallon drop tank and normally had to abandon its charges before the bombers even reached the point where they most needed protection from enemy fighters. Without such protection on a truly effective scale the Eighth was being forced to pull back from its daylight precision bombing campaign, as it could not sustain the level of losses it was incurring.

Along with Rolls-Royce test pilot Ronnie Harker’s brilliant inspiration to marry the Merlin engine with the Mustang airframe, had come a similar and equally influential recommendation from American Air Force Major Thomas Hitchcock “to develop the Mustang, one of the best, if not the best airframe that has been developed in the war, as a high-altitude fighter by cross-breeding it with the Merlin 61 engine.”

Tommy Hitchcock, who was an assistant air attaché at the American embassy in London, added: “. . . while the prospect of an English engine in an American airframe may appeal . . . to those individuals who are interested in furthering Anglo-American relationships . . . it does not fully satisfy important people on both sides of the Atlantic who seem more interested in pointing with pride to the development of a 100-percent national product, then they are concerned with the very difficult problem of developing a fighter plane that will be superior to anything the Germans have.” Fortunately, USAAC General Henry Arnold agreed with Harker and Hitchcock’s assessments and was able to report to President Roosevelt in November 1942 that more than 2,200 Mustangs had just been ordered for his service.

If you find an error or have any questions, please email us at admin@erenow.org. Thank you!