The NA-16 was the first trainer aircraft built by North American Aviation; this was the beginning of a line of closely related North American trainer aircraft that would eventually number more than 17,000 examples.
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 horsepower’s, 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 aluminium 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 centre 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 aluminium, 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.
One for United States Army Air Corps (USAAC) (trials) developed into NA-18 and BT-9 series, powered by Wright R-975 Whirlwind
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
General purpose two-seat aircraft – which became the Harvard I
Two-seat fighter – produced under license in Australia as the CAC Wirraway.
Two-seat light attack bomber.
The first aircraft in this category was the retractable gear NA-26 which evolved into the NA-36 (BC-1).
The fabric-covered fuselage was replaced by an all-metal monocoque to create the NA-44, which provided the basis for a line of light attack bombers whose improvements would result in the AT-6.
Advanced trainer – became the BT-9 for the USAAC and which provided the bulk of early production.
The improvement of the BT-9 with a longer metal skinned fuselage as on the NA-44 would create the NA-64 (Yale) and improved wings would result in the BT-14.
Single-seat fighter – although this designation was never used, it became the NA-50 for Peru, and later the NA-68, which saw limited USAAF service as the P-64.
42 built for USAAC – Minor changes from NA-18, new canopy, powered by Wright R-975 Whirlwind
40 built for USAAC – Armed BT-9 with one cowl gun, one rear flexible gun and modified canopy, powered by Wright R-975 Whirlwind
One built for trials, sold to Honduras (FAH) powered by Wright R-975 Whirlwind
One built for USAAC trials but rejected as severely underpowered.
Open cockpits as per early NA-16 and Townsend ring on engine, powered by Wright R-760 Whirlwind
117 built for USAAC – Unarmed with fixed rear on canopy, powered by Wright R-975 Whirlwind
One modified BT-9B for USAAC – BT-14 prototype with new outer wings, Harvard type canopy, lengthened fabric covered fuselage, triangular rudder and detail alterations, powered by Pratt & Whitney R-985 Wasp Junior
NA-16-3 Basic Combat demonstrator (NA-26)
One armed demonstrator and the first variant with retractable undercarriage, eventually sold to RCAF who modified it with Yale and Harvard parts, powered by Pratt & Whitney R-1340 Wasp
One armed demonstrator sold to Royal Netherlands Air Force – not the same as the previous NA-16-2H, powered by Pratt & Whitney R-1340 Wasp
40 built to US Navy specifications, up engine BT-9B as advanced trainer with fixed gear, powered by Pratt & Whitney R-1340 Wasp
66 built for USAAC – BT-9A with minor changes, powered by Wright R-975 Whirlwind
One built for USAAC – BT-9 with larger engine, similar to USN NJ-1 but armed and detail differences in engine installation, powered by Pratt & Whitney R-1340 Wasp
Cancelled production version of Y1BT-10 for USAAC, powered by Pratt & Whitney R-1340 Wasp
138 built for Sweden’s Flygvapnet as Sk 14/Sk 14A. Sk 14N trialled nosewheel for SAAB 21, powered by Wright R-975 Whirlwind (Sk 14) or Piaggio P VII C (Sk 14A)
One built for Royal Australian Air Force but rejected in favour of NA-16-2K, fixed landing gear, similar to Y1BT-10, powered by Pratt & Whitney R-1340 Wasp
756 for Royal Australian Air Force in Australia with local improvements as CAC Wirraway, powered by Pratt & Whitney R-1340 Wasp
29 built for Argentina (Army Aviation) – 1st major export order (previous orders involved licensed production), powered by Wright R-975 Whirlwind
One built for Imperial Japanese Navy as a technology demonstrator KXA-1 with fixed u/c and three-blade prop., powered by Pratt & Whitney R-985 Wasp Junior
35 built for China (RoCAF) – Fixed gear, fabric covered fuselage, powered by Wright R-975 Whirlwind
Two built for Honduras (FAH), powered by Pratt & Whitney R-1340 Wasp
Intended for Brazil (Army) but order cancelled. Was to have been similar to BT-9C, powered by Wright R-975 Whirlwind
Armed company demonstrator sold to Canada.
Designation reused for AT-6s sold to Brazil (NA-72) and Chile (NA-74), powered by Wright R-1820 Cyclone.
Three built for Venezuela (FAV) similar to USAAC NA-36 BC-1 but with round rudder and bomb racks under wing centre section, powered by Pratt & Whitney R-1340 Wasp
12 built for Brazilian Navy, powered by Wright R-975 Whirlwind
One built for Imperial Japanese Navy as a technology demonstrator KXA-2 similar to NA-16-4R but with a smaller engine, powered by Wright R-975 Whirlwind.
15 built for China (RoCAF) – Retractable undercarriage, fabric covered fuselage, powered by Pratt & Whitney R-1340 Wasp
430 for Royal Air Force and Royal Canadian Air Force as the Harvard I with new canopy and square rudder.
Also used by South Africa and Southern Rhodesia, powered by Pratt & Whitney R-1340 Wasp
50 built for China (RoCAF) – Entirely new design with longer metal fuselage, triangular rudder and later T-6 style wing.
Basically a BT-14 with the AT-6s R-1340 engine and canopy, powered by Pratt & Whitney R-1340 Wasp
230 improved NA-23s for France as NAA 57-P-2, most captured and used by Germany, some retained by Vichy France, powered by Wright R-975 Whirlwind
Three built for Venezuela (FAV), powered by Pratt & Whitney R-1340 Wasp
I.Ae. D.L. 21
An Argentinian version incorporating the NA-16-1 fuselage with locally designed wings.
Rejected in favour of the I.Ae. 22 DL, an original design from the Fabrica Militar de Aviones (FMA).
27 ft 7 in (8.41 m)
42 ft (13 m)
3,078 lb (1,396 kg)
1 × Wright R-975 Whirlwind air cooled radial, 400 hp (300 kW)