North American NA 16

Design and development

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 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 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, and was submitted to the United States Army Air Corps for evaluation as a basic trainer. The Army accepted the trainer for production but with some detail changes. 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). Similar aircraft continued to be sold outside the U.S. under the NA-16 designation.

Foreign developments

Australia

The Commonwealth Aircraft Corporation produced 755 units of a modified version of the NA-16-2K known there as the Wirraway between 1939 and 1946.

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.

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. 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.

NA-16

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:

NA-16-1

General purpose two-seat aircraft - which became the Harvard I

NA-16-2

Two-seat fighter - produced under licence in Australia as the CAC Wirraway.

NA-16-3

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.

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 Chile, and later the NA-68, which saw limited USAAF service as the P-64.

BT-9 (NA-19)

42 built for USAAC - Minor changes from NA-18, new canopypowered 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.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

NA-16-2H (NA-27)

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

NJ-1 (NA-28)

40 built to US Navy specifications, up engined BT-9B as advanced trainer with fixed gear.powered by Pratt & Whitney R-1340 Wasp

BT-9C (NA-29)

66 built for USAAC - BT-9A with minor changes.powered by Wright R-975 Whirlwind

Y1BT-10 (NA-29)

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

BT-10 (NA-30)

Cancelled production version of Y1BT-10 for USAACpowered by Pratt & Whitney R-1340 Wasp

NA-16-4M (NA-31)

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 VIIc (Sk 14A)

NA-16-1A (NA-32)

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

NA-16-2K (NA-33)

756 for Royal Australian Air Force in Australia with local improvements as CAC Wirrawaypowered by Pratt & Whitney R-1340 Wasp

NA-16-4P (NA-34)

29 built for Argentina (Army Aviation) - 1st major export order (previous orders involved licence production).powered by Wright R-975 Whirlwind

NA-16-4R (NA-37)

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

NA-16-4 (NA-41)

35 built for China (RoCAF) - Fixed gear, fabric covered fuselagepowered by Wright R-975 Whirlwind

NA-16-2A (NA-42)

Two built for Honduras (FAH)powered by Pratt & Whitney R-1340 Wasp

NA-16-1G (NA-43)

Intended for Brazil (Army) but order cancelled. Was to have been similar to BT-9Cpowered by Wright R-975 Whirlwind

NA-16-1GV (NA-45)

Three built for Venezuela (FAV) similar to USAAC NA-36 BC-1 but with round rudder and bomb racks under wing center section.powered by Pratt & Whitney R-1340 Wasp

NA-16-4 (NA-46)

12 built for Brazilian Navypowered by Wright R-975 Whirlwind

NA-16-4RW (NA-47)

One built for Imperial Japanese Navy as a technology demonstrator KXA-2 similar to NA-16-4R but smaller engine.powered by Wright R-975 Whirlwind

NA-16-3C (NA-48)

15 built for China (RoCAF) - Retractable undercarriage, fabric covered fuselagepowered by Pratt & Whitney R-1340 Wasp

NA-16-1E (NA-49/NA-61)

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

NA-16-4 (NA-56)

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.powered by Wright R-975 Whirlwind

NA-16-3 (NA-71)

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).

Operators

 Argentina

Army Aviation Service

 Australia

Royal Australian Air Force (RAAF) (samples for licence production)

 Brazil

Brazilian Navy (Marinha do Brasil)

 China

Republic of China Air Force (RoCAF)

 France

French Air Force (Armée de l'Air)

French Naval Aviation (Aéronavale)

Vichy French Air Force

 Germany

Luftwaffe

 Honduras

Honduran Air Force (Fuerza Aérea Hondureña/FAH)

 Japan

Imperial Japanese Navy Air Service(IJNAS) (2 examples for evaluation only)

 Netherlands

Royal Netherlands Air Force (Koninklijke Luchtmacht/KLu)

 South Africa

South African Air Force (SAAF)

 Southern Rhodesia

Southern Rhodesian Air Force (SRAF)

 Sweden

Swedish Air Force (Flygvapnet)

 United Kingdom

Royal Air Force (RAF)

 United States

United States Army Air Corps (USAAC)/United States Army Air Forces (USAAF)

United States Navy (USN)

 Venezuela

Venezuelan Air Force (Fuerza Aérea Venezolana/FAV)

Surviving aircraft

The only intact surviving example of an American built NA-16 is the NA-16-2A/NA-20 "FAH-21" displayed at the Honduras Air Museum at Toncontín.

A Swedish NA-16-4M (locally designated as Sk 14) was built from an ex-RAAF CAC Wirraway (s/n A20-223) with additional parts from an ex-RCAF North American NA-64 Yale and is on display at the Swedish Air Force Museum.

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

A total of 10 are on the Australian civil aircraft register. 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).

Specifications (NA-16)

General characteristics

Crew: two

Length: 27 ft 7 in (8.41 m)

Wingspan: 42 ft (13 m)

Empty weight: 3,078 lb (1,396 kg)

Powerplant: 1 × Wright R-975 Whirlwind air cooled radial, 400 hp (300 kW)

Propellers: 2-bladed Hamilton Standard

Performance

Maximum speed: 170 mph (274 km/h; 148 kn)

Range: 700 mi (608 nmi; 1,127 km)