The North American BT-9 was the

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...

(USAAC) designation for a low-wing single engine

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

primary

trainer aircraft A trainer is a class of aircraft designed specifically to facilitate flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristi ...

that served before and during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. It was a contemporary of the Boeing-Stearman PT-13 Kaydet biplane trainer which pilots learned to fly on before advancing to Basic Flying Training on the BT-9. If they passed, they would continue on to the North American BC-1 and later the AT-6 and other aircraft types specific for each role. During the war, it was discovered that increasing the number of hours of Primary Flying Training eliminated the need for intermediate trainers like the BT-9 and so production never reached the levels for the PT and AT types. The NJ-1 was used by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

for a similar role, but was closer to the one off BT-10.

Design and development

The BT-9, designated NA-19 by the manufacturer, evolved from the North American NA-16, which first flew in April 1935. The BT-9 design first flew in April 1936. The wing and tail control surfaces were fabric-covered, as well as the sides of the fuselage from just behind the firewall to the tail. The remainder of the aircraft was metal-covered and featured fixed (non-retractable) landing gear. The Army Air Corps purchased a total of 199 BT-9s, BT-9As and BT-9Bs. Many foreign countries also used variants of this aircraft under North American's NA-16 designation. The first BT-9C s/n 37-383 was built with a 600 hp

Pratt & Whitney R-1340 The Pratt & Whitney R-1340 Wasp is an aircraft engine of the reciprocating type that was widely used in American aircraft from the 1920s onward. It was the Pratt & Whitney aircraft company's first engine, and the first of the famed Wasp series ...

-41, but was otherwise similar to the normal BT-9Cs. It was delivered as the Y1BT-10, and later redesignated BT-10. The BT-9D was a one off prototype that tested out a number of ideas that went into production as the BT-14 (NA-58), which the similar North American NA-64 Yale represented a major aerodynamic improvement over the NA-16 series, with a longer all-metal fuselage replacing the fabric covered fuselage of the earlier NA-16s. The BT-14 featured a Pratt & Whitney R-985 engine versus the

Wright R-975 Wright is an occupational surname originating in England. The term 'Wright' comes from the circa 700 AD Old English word 'wryhta' or 'wyrhta', meaning worker or shaper of wood. Later it became any occupational worker (for example, a shipwright i ...

used on the BT-9. As well as metal skin replacing the fabric on the fuselage, the fin was moved aft slightly, lengthening the rear fuselage while the engine was moved forward to maintain the

center of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force ma ...

. The rudder was also changed from the rounded shape used previously to one with a roughly triangular shape, with the broadest part being at the bottom, and the canopy was redesigned. The new fuselage would provide the basis for the entire AT-6 family, when fitted with the larger

engine, a new wing with retractable undercarriage and minor changes for a gunners position. The BT-9 suffered from stall/spin problems and a variety of fixes were tried. The USAAC temporarily settled on using slats on the later versions of the BT-9. However these did not work well, and the BT-14s longer fuselage and swept forward outer wing panels, unlike the straight

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...

s of the BT-9 helped somewhat.

Operational history

The NA-26, an improved model with retractable

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

which became the prototype for AT-6 Texan advanced trainer, was developed from the NA-16 design.

Variants

:''Source: Warbirds'' ;NA-16 :Prototype aircraft, one built. ;NA-18 :Pre-production aircraft, one built. ;North American BT-9 :Unarmed two-seat primary trainer for the USAAC, 42 built. EL-2003-00278

;North American BT-9A :Armed with two 0.30 in (7.62 mm) machine guns, 40 built. ;North American BT-9B :Improved unarmed version, 117 built. ;North American BT-9C :Similar to the BT-9B, but with some equipment changes, 97 built. ;North American BT-9D :One prototype only, which led to the development of the BT-14. ;North American Y1BT-10 & BT-10 :One prototype from BT-9C batch re-engined with a 600 hp R-1340-41. ;North American NJ-1 :Two-seat primary trainer aircraft for the USN, powered by a 600 hp (447 kW)

radial piston engine, 40 delivered. North American BT-14 in flight

;North American YBT-14 :Redesignated BT-9D as prototype for BT-14. ;North American BT-14 :Advanced version with lengthened metal fuselage and T-6 outer wing panels, powered by a 450 hp (336 kW) Pratt & Whitney R-985-25 radial piston engine, USAAC, 251 delivered. ;North American BT-14A :27 BT-14s were converted to take the 400 hp (298 kW) Pratt & Whitney R-985-11 radial piston engine.

Operators

; *

(until June 1941) *

United States Army Air Forces The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

(after June 1941) *

Survivors/Aircraft on display

;BT-9 * Museo del Aire de Honduras at Toncontín - BT-9C exported to Honduras as NA-16-2A ; BT-14 "BT-14s."
''AeroWeb''. Retrieved: 24 December 2011. No original aircraft, but several Yales have been painted or partially modified as BT-14s *

Commemorative Air Force The Commemorative Air Force (CAF), formerly known as the Confederate Air Force, is an American non-profit organization based in Dallas, Texas, that preserves and shows historical aircraft at airshows, primarily in the U.S. and Canada. The CAF h ...

- ex RCAF Yale 3450 to be restored as a BT-14 *

National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...

- ex RCAF Yale 3417 displayed as a BT-14

Specifications (BT-9)

References

Notes

Bibliography

* Davis, Larry. ''T-6 Texan in Action (Aircraft Number 94)''. Carrollton, Texas: Squadron/Signal Publications, Inc., 1989. . * Donald, David. ''American Warplanes of World War II''. London: Aerospace Publishing, 1995. . * Fletcher, David C. and Doug MacPhail. ''Harvard! The North American Trainers in Canada.'' San Josef,BC/Dundee,Ont: DCF Flying Books, 1990. . * Hagedorn, Dan. ''North American NA-16/AT-6/SNJ'' (WarbirdTech Volume 11). North Branch, Minnesota: Specialty Press, 1997. . * Morgan, Len. ''Famous Aircraft Series: The AT-6 Harvard''. New York: Arco Publishing Co., Inc., 1965. {{USN trainer aircraft T-9 North American BT-09 Single-engined tractor aircraft Low-wing aircraft World War II trainer aircraft of the United States Aircraft first flown in 1936