The North American Aviation NA-16 was 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
First NA-16 with initial canopy and still in civilian registration
The NA-16 is a family of related single-engine, low-wing monoplanes with tandem seating.[2] Variants could have an open cockpit (the prototype and the NA-22) or be under a glass greenhouse that covered both cockpits.[3] On some variants, the rear of the canopy could be opened for a gunner to fire to the rear.[4] 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.[5] The fuselage was built up from steel tubes and normally fabric covered; however, later versions were provided with aluminum monocoque structures.[6]
During the development of the design, a six-inch stretch was made by moving the rudder post aft.[7] 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).[8] 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.[9] 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.[10] 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.[11]
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.[12] 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.[1]: 20–21, 29–31, 33, 36, 214 Similar aircraft continued to be sold outside the U.S. under the NA-16 designation.[13]
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.[1]: 73
Foreign developments
Australia
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.[14] 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.[1]: 53–56
Argentina
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.[15]
Japan
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.[16] 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.[16]
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:[17]
NA-16-1
General purpose two-seat aircraft - which became the Harvard I[18]
NA-16-2K
Two-seat fighter - produced under licence in Australia as the CAC Wirraway.[19]
NA-16-3
Two-seat light attack bomber. The first aircraft in this category was the retractable gear NA-26[20] which evolved into the NA-36 (BC-1). The fabric-covered fuselage was replaced by an all-metal monocoque to create the NA-44,[21] which provided the basis for a line of light attack bombers whose improvements would result in the AT-6.[22]
NA-16-4
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.
NA-16-5
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.[23]
BT-9 (NA-19)
42 built for USAAC - Minor changes from NA-18, new canopy
powered by Wright R-975 Whirlwind
BT-9A (NA-19A)
40 built for USAAC - Armed BT-9 with one cowl gun, one rear flexible gun and modified canopy.
powered by Wright R-975 Whirlwind
NA-16-2H (NA-20)
One built for trials, sold to Honduras (FAH)
powered by Wright R-975 Whirlwind
NA-22
One built for USAAC trials but rejected as severely underpowered. Open cockpits as per early NA-16 and Townend ring on engine.
powered by Wright R-760 Whirlwind
BT-9B (NA-23)
117 built for USAAC - Unarmed with fixed rear on canopy.
powered by Wright R-975 Whirlwind
BT-9D (NA-23)
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.
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
NA-57
230 improved NA-23s for France as NAA 57-P-2, most captured and used by Germany, some retained by Vichy France.
The only intact surviving example of an American built NA-16 is the NA-16-2A/NA-20 "FAH-21" displayed at the Honduran Aviation Museum at Toncontín.[25]
The CAC Wirraway (originally NA-16-2K) was first modified to British standards and equipment, then later models diverged further from the NA-16 in minor details such as the fitting of dive brakes etc. The sole surviving CA-1 Wirraway is A20-10, the 8th production Wirraway, effectively a licence built NA-16-2K, and held at the Australian National Aviation Museum.[27] Ten Wirraways are on the Australian civil aircraft register.[28] Further examples (in Australia unless noted) are at Temora Aviation Museum, Australian National Aviation Museum, Aviation Heritage Museum, Museum of Victoria, Queensland Air Museum, RAAF Museum (Stored) and the Fantasy of Flight (Florida - stored).
^Some sources list the NA-16 as having been used by the Argentine Air Force however it was with its predecessor, the Army Aviation Service which was dissolved in 1945 when the Air Force was created.
Citations
^ abcdeHagedorn, Dan (2009). North American's T-6: a definitive history of the world's most famous trainer. North Branch, MN: Specialty Press. p. 11. ISBN9781580071246.
^ abFrancillon, René J (1970). The Royal Australian Air Force & Royal New Zealand Air Force in the Pacific. Aero Pictorials 3. California: Aero Publishers Inc, 1970. ISBN978-0-8168-0308-8. Library of Congress Number 76-114412.
^ abcvon Rauch, Georg and David L. Veres. "Argentina's Wooden Warriors". Air Classics (Challenge Publications), Volume 19, March 1983, pp. 14–21.
Bellomo, Sergio (March 2000). "Les N.A.16-4P de l'Aviation de l'Armée Argentine" [The N.A.16-4Ps of Argentine Army Aviation]. Avions: Toute l'aéronautique et son histoire (in French) (84): 38–41. ISSN1243-8650.
Fletcher, David C. and Doug MacPhail. Harvard! the North American Trainers in Canada. San Josef, British Columbia, Canada: DCF Flying Books, 1990. ISBN0-9693825-0-2.
Hagedorn, Dan. North American NA-16/AT-6/SNJ (WarbirdTech Volume 11). North Branch, Minnesota: Speciality Press, 1997. ISBN0-933424-76-0.
MacPhail, Doug and Mikael Östberg. Triple Crown BT-9: The ASJA/Saab Sk 14, A Pictorial Essay (in English/Swedish). San Josef, British Columbia, Canada: DCF Flying Books, 2003.
Smith, Peter Charles. North American T-6: SNJ, Harvard and Wirraway. Ramsbury, Marlborough, Wiltshire, UK: The Crowood Press Ltd., 2000. ISBN1-86126-382-1.
Starkings, Peter. From American Acorn to Japanese Oak - The tale of an unsung Japanese training aircraft with roots extending across the Pacific Ocean. Arawasi International, Asahi Process, September–December 2007, Issue 7.
von Rauch, Georg and David L. Veres. Argentina's Wooden Warriors. Air Classics, Challenge Publications, March 1983, Volume 19 Issue 3, pp. 14–21.
Further reading
Hagedorn, Dan. Texans and Harvards in Latin America. Staplefield, West Sussex: Air-Britain, 2009. ISBN978-0-85130-312-3.
1 X as second letter is for experimental aircraft or imported technology demonstrators not intended for service,
2 Hyphenated trailing letter (-J, -K, -L, -N or -S) denotes design modified for secondary role, 3 Possibly incorrect designation, but used in many sources
Swedish military aircraft designations 1926–current
