North American AT-6 "Texan" a.k.a. "Harvard" - Castle Air Museum

The North American Aviation T-6 Texan is an American single-engined advanced trainer aircraft, which was used to train pilots of the United States Army Air Forces (USAAF), United States Air Force (USAF), United States Navy, Royal Air Force, Royal Canadian 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 the US. Starting in 1948, the new United States Air Force (USAF) designated it the T-6, with the USN following in 1962.

The T-6 Texan remains a popular warbird used for airshow demonstrations and static displays. It has also been used many times to simulate various historical aircraft, including the Japanese Mitsubishi A6M Zero. A total of 15,495 T-6s of all variants have been built.

The Texan's ancestry goes back to the North American NA-16 prototype which was first flown on 1 April 1935. In 1935, NAA submitted this design for the U.S. Army Air Corps Basic Trainer Competition. NAA also targeted the export market.

Modified as the NA-26, it was submitted as an entry for a USAAC "Basic Combat Trainer" aircraft competition in March 1937. Based on the NA-18, but with a foot longer wingspan, it was the first of the NA-16 series with retractable gear. It was similar to the BT-9, but with a larger engine, the 550 hp (410 kW) Pratt & Whitney R-1340 Wasp, and could accommodate two .30 in (7.62 mm) guns.

With minor alterations, 177 unarmed NA-36s would enter service as the BC-1 with a R-1340-47 engine from 9 June 1937. Roughly 30 were modified as BC-1-I instrument trainers. The BC-1A (NA-55-1) followed as an armed version, primarily for Air Corps Reserve and National Guard units, and the 83 built could be equipped with a .30 in (7.62 mm) machine gun on the nose, and a flexible gun in the rear cockpit.

The US Navy received 40 NA-28 aircraft based on the BT-9, which it designated the NJ-1, as well as 16 NA-52s, designated the SNJ-1, 36 NA-65 as SNJ-2s, and 25 NA-79 also as SNJ-2s.

In March 1937, the Commonwealth Aircraft Corporation of Australia purchased an NA-32 (NA-16-1A, with fixed undercarriage) and an NA-33 (NA-16-2K with retractible undercarriage) along with a manufacturing license. The first CAC Wirraway, based on the NA-33, flew on 27 March 1939, of which 755 were built.

In August 1937, Mitsubishi Jukogyo K.K. purchased a single NA-16, NA-16-4R (NA-37), powered by the 450 hp (340 kW) Pratt & Whitney R-985-9CG, including manufacturing rights. A second N-16, NA-16-4RW (NA-47), powered by a smaller Wright engine, was ordered in December 1937. After being evaluated by the Imperial Japanese Navy, Kyusu and K.K. Watanabe Tekkosho chose to ignore the NAA design almost entirely, and built 176 of the somewhat similar K10W1 from 1941 to 1942 which the Allies gave the code name Oak. After WWII, the Japanese Air Self Defense Force operated 195 Texans (9 T-6Ds, 11 T-6Fs, and 175 T-6Gs) and the Japanese Maritime Self Defence Force operated 62 (10 SNJ-4s, 41 SNJ-5s, and 11 SNJ-6s)

According to Dan Hagedorn, "the BC-1A series may be regarded as the true beginning of the modern AT-6 series". In December 1938, the British Commonwealth started receiving the first of 400 Harvard Mark Is (NA-49), for use in the Central Flying School. They were powered by the 600 hp (450 kW) Pratt & Whitney R-1340-S3H1 Wasp. In May 1939, the Royal Canadian Air Force (RCAF) ordered 30 Harvard Mark Is (NA-61). Then in November 1939, the British Purchasing Commission ordered the first of eventually 1275 Harvard Mark IIs (NA-66, NA-75, NA-76, and NA-81) for the Royal Air Force and RCAF.

On 23 April 1939, NAA received a contract for 251 BT-14s and 94 AT-6s. The BT-14 (NA-58) was a fixed gear aircraft with a metal skinned fuselage 14 inches longer than the BT-9. In 1941, 27 BT-14s were refitted with the 400 hp (300 kW) R-985-11, and designated as BT-14A-NAs. In June 1939, NAA received an order for 94 AT-6-NAs (NA-59), powered by the wright R-1340-47 and able to mount two .30 in (7.62 mm) machines guns.

The USAAC AT-6A, and the U.S. Navy SNJ-3, were based on the NA-77 and NA-78 designs. Pratt & Whitney R-1340-49 Wasp radial engine powered the USAAC aircraft, while R-1340-38s powered the Navy aircraft. The USAAC received 1847 AT-6As, and the Navy received 270 SNJ-3s.

The AT-6B (NA-84) was built for armament training, and could mount a .30 in (7.62 mm) machine gun on the right nose cowl, right wing, and in the rear cockpit, and could carry a light bomb rack. The aircraft was powered by the 600 hp (450 kW) R-1340-AN-1 engine. The USAAC received 400.