Question: Who designed the second most produced American fighter aircraft during World War II?

full_context: Document 1: North American T-6 Texan: The North American Aviation T-6 Texan is an American single-engined advanced trainer aircraft used to train pilots of the United States Army Air Forces (USAAF), United States Navy, Royal Air Force, and other air forces of the British Commonwealth during World War II and into the 1970s. Designed by North American Aviation, the T-6 is known by a variety of designations depending on the model and operating air force. The United States Army Air Corps (USAAC) and USAAF designated it as the AT-6, the United States Navy the SNJ, and British Commonwealth air forces the Harvard, the name by which it is best known outside of the US. Starting in 1948, the new United States Air Force (USAF) designated it the T-6, with the USN following in 1962. It remains a popular warbird aircraft used for airshow demonstrations and static displays. It has also been used many times to simulate various Japanese aircraft, including the Mitsubishi A6M Zero in movies depicting World War II in the Pacific.
Document 2: Brewster F2A Buffalo: The Brewster F2A Buffalo was an American fighter aircraft which saw service early in World War II. Designed and built by the Brewster Aeronautical Corporation, it was one of the first U.S. monoplanes with an arrestor hook and other modifications for aircraft carriers. The Buffalo won a competition against the Grumman F4F Wildcat in 1939 to become the U.S. Navy's first monoplane fighter aircraft. Although superior to the Grumman F3F biplane it replaced and the early F4Fs, the Buffalo was largely obsolete when the United States entered the war, being unstable and overweight, especially when compared to the Japanese Mitsubishi A6M Zero.
Document 3: Lockheed F-104 Starfighter: The Lockheed F-104 Starfighter is a single-engine, supersonic interceptor aircraft which later became widely used as an attack aircraft. It was originally developed by Lockheed for the United States Air Force (USAF), but became widely used by US Allies around the world, and produced by several other NATO nations. One of the Century Series of fighter aircraft, it was operated by the air forces of more than a dozen nations from 1958 to 2004. Its design team was led by Kelly Johnson, who contributed to the development of the Lockheed P-38 Lightning, Lockheed U-2, Lockheed SR-71 Blackbird and other Lockheed aircraft.
Document 4: List of surviving Messerschmitt Bf 109s: The Messerschmitt Bf 109 was a German World War II fighter aircraft. It was one of the first true modern fighters of the era, including such features as an all-metal monocoque construction, a closed canopy, and retractable landing gear. The Bf 109 was the most produced fighter aircraft during World War II, with 30,573 examples built during the war, and the most produced fighter aircraft in history, with a total of 33,984 units produced up to April 1945.
Document 5: North American P-51 Mustang: The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in 1940 by North American Aviation (NAA) in response to a requirement of the British Purchasing Commission. The Purchasing Commission approached North American Aviation to build Curtiss P-40 fighters under license for the Royal Air Force (RAF). Rather than build an old design from another company, North American Aviation proposed the design and production of a more modern fighter. The prototype NA-73X airframe was rolled out on 9 September 1940, 102 days after the contract was signed, and first flew on 26 October.
Document 6: Northrop JB-1 Bat: The Northrop JB-1 "Bat" was a United States surface-to-surface cruise missile that was a prototype jet-powered flying wing. The United States Army Air Forces MX-543 program was initiated in September 1942 to use US versions of Frank Whittle's jet engine (US-named General Electric J31). The Northrop Corporation was contracted in late 1943, and only 10 JB-1 airframes were built. A manned version was towed for the 1st flight on "August 27, 1943", ["sic"] from Rogers Dry Lake; and a glider version was launched from a rocket-propelled sled and crashed in December 1944. An unmanned JB-1 powered by an improvised General Electric B-1 turbojet with a wing span of 28 ft made its 1st flight from Eglin Field's Santa Rosa Island, Florida, on December 7, 1944, and crashed 400 yards from the rail launcher.
Document 7: Bell P-39 Airacobra: The Bell P-39 Airacobra was one of the principal American fighter aircraft in service when the United States entered World War II. The P-39 was used by the Soviet Air Force, which scored the highest number of individual kills attributed to any U.S. fighter type in the Eastern European theatre. Other major users of the type included the Free French, the Royal Air Force, the United States Army Air Forces, and the Italian Co-Belligerent Air Force.
Document 8: Vought F4U Corsair: The Vought F4U Corsair is an American fighter aircraft that saw service primarily in World War II and the Korean War. Demand for the aircraft soon overwhelmed Vought's manufacturing capability, resulting in production by Goodyear and Brewster: Goodyear-built Corsairs were designated FG and Brewster-built aircraft F3A. From the first prototype delivery to the U.S. Navy in 1940, to final delivery in 1953 to the French, 12,571 F4U Corsairs were manufactured, in 16 separate models, in the longest production run of any piston-engined fighter in U.S. history (1942–53).
Document 9: Curtiss P-40 Warhawk: The Curtiss P-40 Warhawk is an American single-engined, single-seat, all-metal fighter and ground-attack aircraft that first flew in 1938. The P-40 design was a modification of the previous Curtiss P-36 Hawk which reduced development time and enabled a rapid entry into production and operational service. The Warhawk was used by most Allied powers during World War II, and remained in frontline service until the end of the war. It was the third most-produced American fighter, after the P-51 and P-47; by November 1944, when production of the P-40 ceased, 13,738 had been built, all at Curtiss-Wright Corporation's main production facilities at Buffalo, New York.
Document 10: North American F-82 Twin Mustang: The North American F-82 Twin Mustang was the last American piston-engine fighter ordered into production by the United States Air Force. Based on the P-51 Mustang, the F-82 was originally designed as a long-range escort fighter in World War II. The war ended well before the first production units were operational.
Document 11: Northrop P-61 Black Widow: The Northrop P-61 Black Widow, named for the American spider, was the first operational U.S. warplane designed as a night fighter, and the first aircraft designed to use radar. The P-61 had a crew of three: pilot, gunner, and radar operator. It was armed with four 20 mm (.79 in) Hispano M2 forward-firing cannons mounted in the lower fuselage, and four .50 in (12.7 mm) M2 Browning machine guns mounted in a remote-controlled dorsal gun turret.
Document 12: List of surviving Boeing B-17 Flying Fortresses: The Boeing B-17 Flying Fortress is a four-engine heavy bomber aircraft primarily employed by the United States Army Air Forces (USAAF) during World War II. Developed by Boeing, a total of 12,731 aircraft had been produced by Boeing, Douglas and Lockheed from 1936 until 1945. Over 8,000 were lost in either combat operations or training accidents. The remaining combat veterans and early production models were stored and later scrapped in the vast scrap drives of the late 1940s, many going to aircraft boneyards like Davis-Monthan Air Force Base in Tucson, Arizona, the largest of its kind within the United States' borders.
Document 13: Kawasaki Ki-61: The Kawasaki Ki-61 "Hien" (飛燕, "flying swallow") is a Japanese World War II fighter aircraft used by the Imperial Japanese Army Air Service. The Japanese Army designation was "Army Type 3 Fighter" (三式戦闘機). Allied pilots initially believed Ki-61s were Messerschmitt Bf 109s and later an Italian aircraft, which led to the Allied reporting name of "Tony", assigned by the United States War Department. It was the only mass-produced Japanese fighter of the war to use a liquid-cooled inline V engine. Over 3,000 Ki-61s were produced. Initial prototypes saw action over Yokohama during the Doolittle Raid on 18 April 1942, and continued to fly combat missions throughout the war.
Document 14: Boeing B-17 Flying Fortress: The Boeing B-17 Flying Fortress is a four-engine heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing against Douglas and Martin for a contract to build 200 bombers, the Boeing entry (prototype Model 299/XB-17) outperformed both competitors and exceeded the air corps' performance specifications. Although Boeing lost the contract (to the Douglas B-18 Bolo) because the prototype crashed, the air corps ordered 13 more B-17s for further evaluation. From its introduction in 1938, the B-17 Flying Fortress evolved through numerous design advances, becoming the third-most produced bomber of all time, behind the B-24 and the multirole Ju 88.
Document 15: Messerschmitt Me 262: The Messerschmitt Me 262, nicknamed Schwalbe (German: "Swallow") in fighter versions, or Sturmvogel (German: "Storm Bird") in fighter-bomber versions, was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but problems with engines, metallurgy and top-level interference kept the aircraft from operational status with the Luftwaffe until mid-1944. The Me 262 was faster and more heavily armed than any Allied fighter, including the British jet-powered Gloster Meteor. One of the most advanced aviation designs in operational use during World War II, the Me 262's roles included light bomber, reconnaissance and experimental night fighter versions.
ground_truth: North American Aviation