Design and development
On 14 October 1938, Curtiss test pilot Edward Elliott flew the prototype XP-40, on its first flight in Buffalo. The XP-40 was the 10th production Curtiss P-36 Hawk, with its Pratt & Whitney R-1830 (Twin Wasp) 14-cylinder air-cooled radial engine replaced at the direction of Chief Engineer Don R. Berlin by a liquid-cooled, supercharged Allison V-1710 V-12 engine. The first prototype placed the glycol coolant radiator in an underbelly position on the fighter, just aft of the wing's trailing edge. USAAC Fighter Projects Officer Lieutenant Benjamin S. Kelsey flew this prototype some 300 miles in 57 minutes, approximately 315 miles per hour (507 km/h). Hiding his disappointment, he told reporters that future versions would likely go 100 miles per hour (160 km/h) faster. Kelsey was interested in the Allison engine because it was sturdy and dependable, and it had a smooth, predictable power curve. The V-12 engine offered as much power as a radial engine but had a smaller frontal area and allowed a more streamlined cowl than an aircraft with radial engines, promising a theoretical 5% increase in top speed.
Curtiss engineers worked to improve the XP-40's speed by moving the radiator forward in steps. Seeing little gain, Kelsey ordered the aircraft to be evaluated in a NACA wind tunnel to identify solutions for better aerodynamic qualities. From 28 March to 11 April 1939, the prototype was studied by NACA. Based on the data obtained, Curtiss moved the glycol coolant radiator forward to the chin; its new air scoop also accommodated the oil cooler air intake. Other improvements to the landing gear doors and the exhaust manifold combined to give performance that was satisfactory to the USAAC. Without beneficial tail winds, Kelsey flew the XP-40 from Wright Field back to Curtiss's plant in Buffalo at an average speed of 354 mph (570 km/h). Further tests in December 1939 proved the fighter could reach 366 mph (589 km/h).
An unusual production feature was a special truck rig to speed delivery at the main Curtiss plant in Buffalo, New York. The rig moved the newly built P-40s in two main components, the main wing and the fuselage, the eight miles from the plant to the airport where the two units were mated for flight and delivery.
The P-40 was originally conceived as a pursuit aircraft and was very agile at low and medium altitudes but suffered due to lack of power at higher altitudes. At medium and high speeds it was one of the tightest turning early monoplane designs of the war, and it could out turn most opponents it faced in North Africa and the Russian Front. In the Pacific Theater, like all Allied Fighters it was out turned at lower speeds by the lightweight fighters A6M Zero and Nakajima Ki-43 "Oscar" which did not possess the structural strength of the P-40 for high speed hard turns. The American Volunteer Group Commander Claire Chennault advised against prolonged dog fighting with the Japanese fighters due to the resulting airspeed reduction which favored the lightweight Japanese designs' low speed turning superiority.
Allison V-1710 engines produced about 1,040 hp (780 kW) at sea level and at 14,000 ft (4,300 m): not powerful by the standards of the time and the early P-40 variants' top speeds were only average. Also, the single-stage, single-speed supercharger meant that the P-40 could not compete with contemporary designs as a high-altitude fighter. Later versions, with 1,200 hp (890 kW) Allisons or more powerful 1,400 hp Packard Merlin engines were more capable. Climb performance was fair to poor, depending on the subtype. Dive acceleration was good and dive speed was excellent. The highest-scoring P-40 ace, Clive Caldwell (RAAF), who claimed 22 of his 28½ kills in the type, said that the P-40 had "almost no vices", although "it was a little difficult to control in terminal velocity". Caldwell added that the P-40 was "faster downhill than almost any other aeroplane with a propeller." The P-40 had one of the fastest maximum dive speeds of any fighter of the early war period and good high speed handling.
The P-40 tolerated harsh conditions in the widest possible variety of climates. It was a semi-modular design and thus easy to maintain in the field. It lacked innovations of the time, such as boosted ailerons or automatic leading edge slats, but it had a strong structure including a five-spar wing, which enabled P-40s to pull high G turns and even survive some midair collisions: both accidental impacts and intentional ramming attacks against enemy aircraft were occasionally recorded as victories by the Desert Air Force and Soviet Air Forces. Caldwell said P-40s "would take a tremendous amount of punishment, violent aerobatics as well as enemy action." Operational range was good by early war standards, and was almost double that of the Supermarine Spitfire or Messerschmitt Bf 109, although it was inferior to the Mitsubishi A6M Zero, Nakajima Ki-43 and Lockheed P-38 Lightning.
Caldwell found the P-40C Tomahawk's armament of two .50 in (12.7 mm) Browning AN/M2 "light-barrel" dorsal nose-mount synchronized machine guns and two .303 Browning machine guns in each wing to be inadequate. This was rectified with the P-40D (Kittyhawk I) which abandoned the synchronized gun mounts and instead had two .50 in (12.7 mm) guns in each wing, although Caldwell still preferred the earlier Tomahawk in other respects. The D had armor around the engine and the cockpit, which enabled it to withstand considerable damage. This was one of the characteristics that allowed Allied pilots in Asia and the Pacific to attack Japanese fighters head on, rather than try to out-turn and out-climb their opponents. Late-model P-40s were regarded as well armored. Visibility was adequate, although hampered by an overly complex windscreen frame, and completely blocked to the rear in early models due to the raised turtledeck. Poor ground visibility and the relatively narrow landing gear track led to many losses due to accidents on the ground.
While early models of the P-40 were being produced, Curtiss began testing a follow-on design, the Curtiss XP-46. As it offered no particular improvements over the latest P-40s, the program was cancelled.
In April 1939, the U.S. Army Air Corps, having witnessed the new, sleek, high-speed, in-line-engined fighters of the European air forces, placed the largest single fighter order it had ever made: 524 P-40s.
Chinese Air Force
Flying Tigers (American Volunteer Group)
The Flying Tigers, known officially as the 1st American Volunteer Group (AVG), were a unit of the Chinese Air Force, recruited from U.S. aviators. From late 1941, the P-40B was used by the Flying Tigers. They were divided into three pursuit squadrons, the "Adam & Eves", the "Panda Bears" and the "Hell's Angels".
Compared to opposing Japanese fighters, the P-40B's strengths were that it was sturdy, well armed, faster in a dive and possessed an excellent rate of roll. While the P-40s could not match the maneuverability of the Japanese Army air arm's Nakajima Ki-27s and Ki-43s, nor the much more famous Zero naval fighter in a slow speed turning dogfight, at higher speeds the P-40s were more than a match. AVG leader Claire Chennault trained his pilots to use the P-40's particular performance advantages. The P-40 had a higher dive speed than any Japanese fighter aircraft of the early war years, for example, and could be used to exploit so-called "boom-and-zoom" tactics. The AVG was highly successful, and its feats were widely published, to boost sagging public morale at home, by an active cadre of international journalists. According to their official records, in just 6 1/2 months, the Flying Tigers destroyed 115 enemy aircraft for the loss of just four of their own in air-to-air combat.
The Model B's received by Chennault and assembled in Burma at the end of 1941 were not well liked. There were no auxiliary fuel tanks that could be dropped before going into combat, and there were no bomb racks on the wings. Chennault considered the liquid-cooled engine vulnerable in combat because a single bullet through the coolant tank would cause the engine to overheat in minutes. The Tomahawks also had no radios, so the AVG improvised by installing a fragile radio transceiver, RCA-7-H, which had been built for a Piper Cub. Because the plane lacked a turbo-supercharger, its effective ceiling was about 25,000 feet. The most critical problem was the lack of spare parts; the only source of spare parts was damaged aircraft. The planes were thought to be what no one else wanted, dangerous and difficult to fly. But the plane had advantages: its gas tanks were self-sealing and could take hits without catching on fire. There were two heavy sheets of steel behind the pilot's head and back. The plane as a whole was ruggedly constructed.
In the spring of 1942, the AVG received a small number of Model E's, each equipped with a radio, six .50-caliber machine guns, and auxiliary bomb racks that could hold 35-lb fragmentation bombs. Chennault's armorer fitted the new planes with additional bomb racks that held the 570-lb Russian bombs, which the Chinese had in abundance. These planes were used in the battle of the Salween River Gorge in late May, 1942, which kept the Japanese from entering China from Burma and threatening Kunming. Spare parts were still a problem. "Scores of new planes...were now in India, and there they stayed--in case the Japanese decided to invade....the AVG was lucky to get a few tires and spark plugs with which to carry on its daily war."
4th Air Group
China received 27 P-40E in early 1943. These were assigned to squadrons of the 4th Air Group.
United States Army Air Forces
A total of 15 entire USAAF pursuit/fighter groups (FG), along with other pursuit/fighter squadrons and a few tactical reconnaissance (TR) units, operated the P-40 during 1941–45.
As was also the case with the Bell P-39 Airacobra, many USAAF officers considered the P-40 exceptional, but it was gradually replaced by the Lockheed P-38 Lightning, the Republic P-47 Thunderbolt and the North American P-51 Mustang. However, the bulk of the fighter operations by the USAAF in 1942–43 were borne by the P-40 and the P-39. In the Pacific, these two fighters, along with the U.S. Navy's Grumman F4F Wildcat, contributed more than any other U.S. types to breaking Japanese air power during this critical period.
The P-40 was the main USAAF fighter aircraft in the South West Pacific and Pacific Ocean theaters during 1941–42.
In the first major battles, at Pearl Harbor and in the Philippines, USAAF P-40 squadrons suffered crippling losses on the ground and in the air to Japanese fighters such as the Ki-43 Oscar and A6M Zero. During the attack on Pearl Harbor, a few P-40s managed to shoot down several Japanese planes, most notably by George Welch and Kenneth Taylor.
However, in the Dutch East Indies campaign, the 17th Pursuit Squadron (Provisional), formed from USAAF pilots evacuated from the Philippines, claimed 49 Japanese aircraft destroyed, for the loss of 17 P-40s The seaplane tender USS Langley was sunk by Japanese planes while delivering P-40s to Tjilatjap, Java. In the Solomon Islands and New Guinea Campaigns, as well as the air defense of Australia, improved tactics and training allowed the USAAF to more effectively utilize the strengths of the P-40.
Due to aircraft fatigue, scarcity of spare parts and replacement problems, the US Fifth Air Force and Royal Australian Air Force created a joint P-40 management and replacement pool on 30 July 1942 and many P-40s went back and forth between the air forces.
The 49th Fighter Group was in action in the Pacific from the beginning of the war. Robert DeHaven scored 10 kills (of 14 overall) in the P-40 with the 49th FG. He compared the P-40 favorably with the P-38:
- "If you flew wisely, the P-40 was a very capable aircraft. [It] could outturn a P-38, a fact that some pilots didn't realize when they made the transition between the two aircraft. [...] The real problem with it was lack of range. As we pushed the Japanese back, P-40 pilots were slowly left out of the war. So when I moved to P-38s, an excellent aircraft, I did not [believe] that the P-40 was an inferior fighter, but because I knew the P-38 would allow us to reach the enemy. I was a fighter pilot and that was what I was supposed to do."
The 8th, 15th, 18th, 24th, 49th, 343rd and 347th PGs/FGs, flew P-40s in the Pacific theaters between 1941 and 1945, with most units converting to P-38s during 1943-44. In 1945, the 71st Reconnaissance Group employed them as armed forward air controllers during ground operations in the Philippines until it received delivery of P-51s. They claimed 655 aerial victories.
Contrary to conventional wisdom, with sufficient altitude the P-40 could actually turn with the A6M and other Japanese fighters, using a combination of a nose-down vertical turn with a bank turn, a technique known as a low yo-yo. Robert DeHaven describes how this tactic was used in the 49th Fighter group:
- You could fight a Jap on even terms, but you had to make him fight your way. He could outturn you at slow speed. You could outturn him at high speed. When you got into a turning fight with him, you dropped your nose down so you kept your airspeed up, you could outturn him. At low speed he could outroll you because of those big ailerons ... on the Zero. If your speed was up over 275, you could outroll a Zero. His big ailerons didn't have the strength to make high speed rolls... You could push things, too. Because ... if you decided to go home, you could go home. He couldn't because you could outrun him. [...] That left you in control of the fight.
China Burma India Theater
USAAF and Chinese P-40 pilots performed well in this theater, scoring high kill ratios against Japanese types such as the Ki-43, Nakajima Ki-44 "Tojo" and the Zero. The P-40 remained in use in the China Burma India Theater (CBI) until 1944, and was reportedly preferred over the P-51 Mustang by some US pilots flying in China.
The American Volunteer Group (Flying Tigers) was integrated into the USAAF as the 23rd Fighter Group in June 1942. The unit continued to fly newer model P-40s until the end of the war, racking up a high kill-to-loss ratio. In the very important Battle of the Salween River Gorge of May 1942 the AVG used the P40E model equipped with wing racks that could carry six 35-pound fragmentation bombs; in addition, Chennault's armorer developed belly racks for the planes that could carry the Russian 570-pound bombs, which the Chinese had in large quantity...
Units arriving in the CBI after the AVG in the 10th and 14th Air Forces continued to perform well with the P-40, claiming 973 kills in the theater, or 64.8 percent of all enemy aircraft shot down. Aviation historian Carl Molesworth stated that "...the P-40 simply dominated the skies over Burma and China. They were able to establish air superiority over free China, northern Burma and the Assam valley of India in 1942, and they never relinquished it."
In addition to the 23rd FG, the 3rd, 5th, 51st and 80th FGs, along with the 10th TRS, operated the P-40 in the CBI. In addition to its role as a fighter aircraft, CBI P-40 pilots used the aircraft very effectively as a fighter-bomber. The 80th Fighter Group in particular used its so-called B-40 (P-40s carrying 1,000-pound high explosive bombs) to destroy Japanese-held bridges and kill bridge repair crews, sometimes demolishing their target with a single bomb. At least 40 U.S. pilots reached ace status while flying the P-40 in the CBI.
Europe and Mediterranean theaters
On 14 August 1942, the first confirmed victory by a USAAF unit over a German aircraft in World War II was achieved by a P-40C pilot. 2nd Lt Joseph D. Shaffer, of the 33rd Fighter Squadron, intercepted a Focke-Wulf Fw 200C-3 maritime patrol plane that overflew his base at Reykjavík, Iceland. Shaffer damaged the Fw 200, which was finished off by a P-38F.
Warhawks were used extensively in the Mediterranean Theater of Operations (MTO) by USAAF units, including the 33rd, 57th, 58th, 79th, 324th and 325th Fighter Groups.
While the P-40 suffered heavy losses in the MTO, many USAAF P-40 units achieved high kill-to-loss ratios against Axis aircraft. For example, the 324th FG scored better than a 2:1 ratio in the MTO. In all, 23 U.S. pilots became aces in the MTO while flying the P-40, most of them during the first half of 1943. As in the Pacific, success in combat depended in part on experience and effective tactics.
Individual pilots from the 57th FG were the first USAAF P-40 pilots to see action in the MTO, while attached to Desert Air Force Kittyhawk squadrons, from July 1942. The 57th was also the main unit involved in the "Palm Sunday Massacre", on 18 April 1943. Decoded Ultra signals had given away a plan for a large formation of German Junkers Ju 52 transports to cross the Mediterranean, escorted by German and Italian fighters. Between 1630 and 1830 hours, all wings of the group were engaged in an intensive effort against the enemy air transports. Of the four Kittyhawk wings, three had left the patrol area before a convoy of a 100+ enemy transports were sighted by 57 Group, which tallied 74 aircraft destroyed. 57 Group was last in the area, and intercepted the Ju 52s escorted by large numbers of Bf 109s, Bf 110s and Macchi C.202s. In all, they claimed 58 Ju 52s, 14 Bf 109s and two Bf 110s destroyed, with a number of others probably destroyed and damaged. Between 20 and 40 of the Axis aircraft landed on the beaches around Cap Bon to avoid being shot down. Six Allied fighters were lost, five of them P-40s.
On 22 April, in Operation Flax, a similar force of P-40s attacked a formation of 14 Messerschmitt Me 323 Gigant ("Giant") six-engine transports, covered by seven Bf 109s from II./JG 27. All the transports were shot down, for a loss of three P-40s destroyed. The 57th FG was equipped with the Curtiss fighter until early 1944, during which time they were credited with at least 140 air-to-air kills.
On 23 February 1943, during Operation Torch, the pilots of the 58th FG flew 75 P-40Ls off the aircraft carrier USS Ranger to the newly captured Vichy French airfield, Cazas, near Casablanca, in French Morocco. The aircraft resupplied the 33rd FG and the pilots were reassigned.
The 325th FG (known as the "Checkertail Clan") flew P-40s in the MTO. The 325th was credited with at least 133 air-to-air kills in April–October 1943, of which 95 were Bf 109s and 26 were Macchi C.202s, for the loss of 17 P-40s in combat. An anecdote concerning the 325th FG, indicates what could happen if Bf 109 pilots made the mistake of trying to out-turn the P-40. 325th FG historian Carol Cathcart wrote: "on 30 July, 20 P-40s of the 317th [Fighter Squadron] ... took off on a fighter sweep ... over Sardinia. As they turned to fly south over the west part of the island, they were attacked near Sassari... The attacking force consisted of 25 to 30 Bf 109s and Macchi C.202s... In the brief, intense battle that occurred ... [the 317th claimed] 21 enemy aircraft." Cathcart states that Lt. Robert Sederberg who assisted a comrade being attacked by five Bf 109s, destroyed at least one German aircraft, and may have shot down as many as five. Sederberg was shot down in the dogfight and became a prisoner of war.
A famous African-American unit, the 99th FS, better known as the "Tuskegee Airmen" or "Redtails", flew P-40s in stateside training and for their initial eight months in the MTO. On 9 June 1943, they became the first African-American fighter pilots to engage enemy aircraft, over Pantelleria, Italy. A single Focke Wulf Fw 190 was reported damaged by Lieutenant Willie Ashley Jr. On 2 July the squadron claimed its first verified kill; a Fw 190 destroyed by Captain Charles Hall. The 99th continued to score with P-40s until February 1944, when they were assigned P-39s and P-51 Mustangs.
The much-lightened P-40L was most heavily used in the MTO, primarily by U.S. pilots. Many US pilots stripped down their P-40s even further to improve performance, often removing two or more of the wing guns from the P-40F/L.
"My final year in high school, I convinced myself that, above all else, I wanted to become an artist, and started a vigorous inquiry into every school of art within a thousand miles of my hometown Pittsburgh," Biederman wrote in his autobiography, published in the November-December 1970 issue of Horseless Carriage Gazette. He attended the American Academy of Art in Chicago. "The only entrance requirement consisted of artistic proof of one's ability, so I prepared a complete catalog featuring an imaginary automobile. Each page portrayed a separate model, each laboriously rendered in profile, all in full and glorious color. When this massive document was finally lashed together, it possessed all the weight and characteristics of a suitcase loaded with bricks. Thus, for better or worse, my artistic career was launched."
Biederman graduated from the Academy in October 1932, and like many of his contemporaries, the rigors of the Depression meant that it took him three years to find a job in his field. "My introduction to the advertising world was a revelation akin to the opening of 1,000 doors," he wrote. "Such mysteries as art direction, layout, production, type, reproduction-all unfolded in rapid succession...I survived this routine for years, but slowly and inevitably had begun the realization that the artist must at some time look to specialization and away from generalization in order that he might achieve recognition, prominence, and even fame. In 1940, I departed the advertising affair for the calmer atmosphere of a studio.
"I turned my full attention and energies to transportation vehicles...on/in the water, air and land," he continued. "Movement in its various forms has dominated my time, my thinking, and my life these past thirty years. In the years that followed, I did become known and my particular specialty recognized, but many detours were necessary, including art directorships, freelance artist, etc. As my exhibits became more numerous and my sells more regular, exposure of my efforts began to enter into commercial channels...calendars, prints, premiums, novelties, magazines, as well as other channels."
As Biederman's expanding body of work was gaining him prominence, he began a relationship with the McCleery-Cumming Corporation in 1956; this calendar company retained the artist to create six paintings for each of their 1958 automobile calendars. He painted for the calendar company for 36 years, and in the first 31 of those years, 186 automobile paintings were printed without interruption. A total of 444 Biederman transportation paintings were published in McCleery-Cumming calendars by 1993. In addition to the calendars, Mr. Biederman's automotive paintings were featured prominently in Playboy magazine, Automobile Quarterly and Horseless Carriage Gazette. He retired at the age of 75, in 1988, and died in 1996.
According to his widow, most of Biederman's paintings were done in tempera on heavyweight 20 x 30-inch illustration board. Calendar art averaged roughly 10 x 15 inches, depending on the subject. A substantial portion of Biederman's body of work remains intact, and most originals are available for purchase at $1,200 apiece.
"It seems to me that despite the untold millions of devotees adherent to this, that and the other...the fundamental 'love affair' lies in and with the internal combustion engine, the good, bad or indifferent that surrounds it," Biederman wrote. "The combination of motor, wheels and body, has known, knows, and will experience moments of greatness, be they in performance, styling, concept, even flights of fancy."