The North American Aviation NA-16 is the first trainer aircraft built by North American Aviation, and was the beginning of a line of closely related North American trainer aircraft that would eventually number more than 17,000 examples, notably the T-6 Texan family.

Design and development

On 10 December 1934, James Howard "Dutch" Kindelberger, John L. "Lee" Atwood, and H.R. Raynor sketched out the specifications for the NA-16. A key characteristic for the advanced trainer was a closed canopy. The NA-16 is a family of related single-engine, low-wing monoplanes with tandem seating. Variants could have an open cockpit (the prototype and the NA-22) or be under a glass greenhouse that covered both cockpits. On some variants, the rear of the canopy could be opened for a gunner to fire to the rear. A variety of air-cooled radial engines, including the Wright Whirlwind, Pratt & Whitney Wasp and Pratt & Whitney Wasp Junior of varying horsepowers, could be installed depending on customer preferences. The fuselage was built up from steel tubes and normally fabric covered; however, later versions were provided with aluminum monocoque structures. During the development of the design, a six-inch stretch was made by moving the rudder post aft. Many versions had a fixed landing gear, but later versions could have retractable gear, mounted in a widened wing center section (which could have either integral fuel tanks or not). Most had a straight trailing edge on the outer wing while again, some had the wing trailing edge swept forward slightly in an attempt to fix a problem with stalls and spins. Several different rudders were used, with early examples having a round outline, intermediate examples having a square bottom on the rudder (Harvard I) and late examples using the triangular rudder of the AT-6 series, due to a loss of control at high angles of attack with the early types. Horizontal and vertical tails were initially covered in corrugated aluminum, but later examples were smooth-skinned, and the horizontal stabilizer was increased in chord near its tips on later versions. The NA-16 flew for the first time on 1 April 1935, by Eddie Allen. An enclosed cockpit version of the NA-16 was submitted to the United States Army Air Corps for performance tests as a basic trainer on 27 May 1935. The Army accepted the trainer for production but with some detail changes, including a larger engine and faired landing gear modifications. The modified NA-16 was redesignated by North American as the NA-18, with production examples entering Air Corps service as the North American BT-9 (NA-19). The U.S. Army Air Corps ordered 42 BT-9s, equipped with the Wright R-975 Whirlwind engine, and 40 BT-9As, which could be armed with .30 cal. Browning M-1 machine guns. In 1936, an order was placed for 117 BT-9Bs, without armament. A total of 67 BT-9Cs (NA-29) were built, using the same R-975-7 engine. Similar aircraft continued to be sold outside the U.S. under the NA-16 designation. By the time of the U.S. entry into WWII, the NAF had built 1631 N-16 series aircraft. Of that total, 1043 were for foreign countries, while the remainder were for the U.S. Army Air Corps and Navy.

Foreign developments

The Commonwealth Aircraft Corporation produced 755 units of a modified version of the NA-16-2K (NA-33) known there as the Wirraway between 1939 and 1946. The units built included 40 CA-1s (Wirraway I), 60 CA-3s, 32 CA-5s, 100 CA-7s, 200 CA-8s, 188 CA-9s, and 135 CA-16s. The CA-16s were called the Wirraway IIIs, while previous models were called Wirraway IIs. Experience with the NA-16-4P and deteriorating political relations with the US led to the local development of the I.Ae. D.L. 21, which shared the NA-16 fuselage structure; however it proved too difficult to produce. As a result of this, an entirely new design (the I.Ae. D.L. 22) was built instead; it had similar configuration, but was structurally different and optimized to available materials. The NA-16-4RW and NA-16-4R inspired the development of the Kyushu K10W when the Imperial Japanese Navy instructed Kyushu to develop something similar. The resulting aircraft owed little to the NA-16, however Allied Intelligence saw so few examples that the error was not corrected and some drawings show a modified NA-16.

Variants

Listing includes aircraft built specifically under NA-16 designation for export, and similar aircraft built for use by the United States armed forces. When the North American NA-16 was first conceived, five different roles were intended for the design, designated NA-16-1 thru NA-16-5:

Operators

Surviving aircraft

Specifications (NA-16)

Citations