<p>The Stearman Aircraft Company, formed by Lloyd Stearman in 1927, became identified as the Wichita Division of the Boeing Airplane Company in 1939. As early as 1933 the company began design and construction of a new training biplane, derived from the earlier Stearman Model C; built as a private venture, this was first flown in December 1933 and, designated originally as the Stearman X70, was submitted as a contender in 1934 to meet a US Army Air Corps requirement for a new primary trainer.
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<p>The first service to show positive interest in this aircraft was the US Navy which, in early 1935, contracted for the supply of 61 Stearman Model 70s under the designation NS-1 (Trainer, Stearman, 1). These, however, received a different powerplant to that installed originally, for the US Navy had in storage a quantity of 225-hp (168-kW) Wright J-5 (R-790-8) radial engines which were specified for installation in this initial order, the company changing the model number of aircraft so equipped to Model 73. The X70 supplied for US Army evaluation was subjected to protracted testing and eventually, in early 1936, the USAAC contracted for the supply of 26 aircraft under the designation PT-13 (Primary Trainer, 13). These, powered by 215-hp (160-kW) Lycoming R-680-5 engines, were the first of the Stearman Model 75s.
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<p>This cautious approach by the US Army should not be considered as a reflection upon the capability of the new trainer. The truth of the matter was that at that period the USAAC had little money to spend on new aircraft: not only had this service to be as certain as possible that it was procuring the best available, but even then was only able to procure small quantities. Soon, however, the fortunes of war were to bring Boeing contracts for thousands of the Stearman-designed trainers and although, officially, the aircraft were Boeing Model 75s from 1939, they were persistently regarded as Stearman 75s throughout the war. The name Kaydet, bestowed later by Canada, and adopted generally in reference to these aircraft, was also unofficial except in Canada.
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<p>This attractive two-seat biplane was of mixed construction, the single-bay wings being basically of wood with fabric covering, the remainder of welded steel-tube structure with mostly fabric covering.
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<p>Landing gear was non-retractable tailwheel type, the divided cantilever main units having cleanly faired oleo-spring shock absorbers. The powerplant was to vary considerably throughout a production run which lasted until early 1945, and during which well over 10,000 examples were built.
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<p>USAAC procurement continued with 92 PT-13As delivered from 1937, these having improved instrumentation and 220-hp (164-kW) R-680-7 engines, and by the end of 1941 the USAAF had received an additional 255 PT-13Bs with R-680-11 engines and only minor equipment changes. The designation PT-13C was allocated in 1941 to six PT-13As which were converted by the addition of equipment necessary to make them suitable for night or instrument flight. A change of powerplant, the 220-hp (164-kW) Continental R-670-5 engine installed in a PT-13A type airframe, brought the designation PT-17, and 3,519 of these were built during 1940 to meet the enormous demand for training aircraft. Eighteen PT-17s were equipped with blind-flying instrumentation under the designation PT-17A, and three with agricultural spraying equipment for pest control became PT-17Bs. Aircraft remaining in service after 1948 were assigned the designation T-17.
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<p>US Navy procurement during this same period included a first batch of 250 Model 75s with Continental R-670-14 engines, designated N2S-1, followed by 125 with Lycoming R-680-8 engines as N2S-2. N2S-3s, totalling 1,875, had Continental R-670-4 engines, and 99 aircraft diverted from US Army PT-17 production plus 577 similar aircraft on US Navy contracts were designated N2S-4. For the first time both the US Army and US Navy had a common model in 1942, basically the PT-13A airframe with a Lycoming R-680-17 engine, and these had the respective designations PT-13D and N2S-5. These were to be the last major production variants for the US forces, the US Army receiving 318 and the US Navy 1,450. A shortage of engines in 1940-41 had, however, produced two other designations: PT-18 and PT-18A. The first related to 150 aircraft with the PT-13A type airframe and a 225-hp (168-kW) Jacobs R-755-7 engine, and the six PT-18As were six of the PT-18s converted subsequently with blind-flying instrumentation. The designation PT-27 applied to 300 aircraft procured by the US Army for supply under Lend-Lease to the Royal Canadian Air Force. A small number of these, and of the N2S-5s supplied to the US Navy, had cockpit canopies, cockpit heating, full blind-flying instrumentation and a hood for instrument training. In North America the Stearman Kaydet retains an aura of nostalgia which Britons equate with such aircraft as the Avro 504 and Tutor, and de Havilland Tiger Moth, or Germans with the Bucker trainers. When declared surplus at the war's end many served with the air forces of other nations, and large numbers were converted for use as agricultural aircraft. Many remained in operation in this latter role in the 1980s, and the Kaydet is undoubtedly a collector's piece.
<item><hi format=bold>Powerplant:</hi> one 220-hp (164-kW) Lycoming R-680-17 radial piston engine
<item><hi format=bold>Performance:</hi> maximum speed 124 mph (200 km/h); cruising speed 106 mph (171 km/h); service ceiling 11,200 ft (3,415 m); range 505 miles (813 km)
<item><hi format=bold>Weights:</hi> empty 1,936 lb (878 kg); maximum take-off 2,717 lb (1,232 kg)
<item><hi format=bold>Dimensions:</hi> span 32 ft 2 in (9.80 m); length 25 ft 0 in (7.63 m); height 9 ft 2 in (2.79 m); wing area 297 sq ft (27.59 m<su>2</su>)
