Boeing-Stearman Model 75


The Stearman Model 75 is an American biplane formerly used as a military trainer aircraft, of which at least 10,626 were built in the United States during the 1930s and 1940s. Stearman Aircraft became a subsidiary of Boeing in 1934. Widely known as the Stearman, Boeing Stearman, or Kaydet, it served as a primary trainer for the United States Army Air Forces, the United States Navy, and with the Royal Canadian Air Force as the Kaydet throughout World War II. After the conflict was over, thousands of surplus aircraft were sold on the civilian market. In the immediate postwar years, they became popular as crop dusters and sports planes, and for aerobatic and wing walking use in air shows.

Design and development

In late 1933, Stearman engineers Mac Short, Harold W. Zipp, and J. Jack Clark took a 1931 Lloyd Stearman design, and added cantilever landing gear and adjustable elevator trim tabs, to produce the Model 70. Able to withstand +12g and -9g, the aircraft was powered by a 210-hp Lycoming R-680, first flew on 1 January 1934, before flight tests were conducted at Wright Field, Naval Air Station Anacostia, and Pensacola. The Navy then requested a similar model built to Navy specifications, including a 200-hp Wright J-5 engine. The resultant Model 73, was designated NS-1 by the Navy, of which 41 were ordered, including enough spares to build another 20 aircraft.
In the summer of 1934, Stearman engineers refined the Model 73 into the Model X75. The Army Air Corps evaluated the plane that autumn, powered by a 225-hp Wright R-760 or a 225-hp Lycoming R-680. In July 1935, the Army Air Corps ordered 26 with the Lycoming engine, designated the PT-13A, while the navy ordered an additional 20. In August 1936, the Army ordered an additional 50 PT-13As, followed by another 30 in October, and another 28 in December. Simultaneously, the company received orders for its primary trainer from the Argentinian navy, the Philippine Army Air Corps, and the Brazilian Air Force. In January 1937, the army ordered another 26 PT-13As.
On 6 June 1941, the U.S. government issued Approved Type Certificate No. 743 for the civilian version of the Model 75. Designated the Model A75L3 and Model A75N1, about 60 were sold to civilian flights schools such as Parks College of Engineering, Aviation and Technology, and for export.
On 15 March 1941, the company delivered the 1000th trainer to the Army, and the 1001st trainer to the Navy. Then on 27 August 1941, the company delivered the 2000th trainer to the Army. On 27 July 1944, the company delivered its 10,000th primary trainer.
The Kaydet was a conventional biplane of rugged construction, with a large, fixed tailwheel undercarriage, and accommodation for the student and instructor in open cockpits in tandem. The radial engine was usually not cowled, although some Stearman operators choose to cowl the engine, most notably the .

Operational history

Post-war usage

After World War II, thousands of surplus PT-17s were auctioned off to civilians and former military pilots. Many were modified for crop-dusting use, with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars, and nozzles mounted below the lower wings. A popular approved modification to increase the maximum takeoff weight and climb performance involved fitting a larger Pratt & Whitney R-985 Wasp Junior engine and a constant-speed propeller.

Variants

Data from: United States Navy aircraft since 1911, Boeing aircraft since 1916 8,584 Model 70s, 75s and 76s were built, with additional "spares" bringing the number up to the sometimes quoted 10,346.

USAAC/USAAF designations

The U.S. Army Air Forces Model 75 Kaydet had three different designations, PT-13, PT-17 and PT-18, depending on which type of radial engine was installed.
;PT-13: Initial production version with Lycoming R-680-B4B engine, 26 built in 1936
;PT-17: Version with Continental R-670-5 engine, 2,942 delivered.
;PT-18 :Version with Jacobs R-755-7 engine, 150 built. Further production was cancelled as the engines were needed for other types of trainers.
;PT-27

US Navy designations

;NS
;N2S :Known colloquially as the "Yellow Peril" from its overall yellow paint scheme.

Company designations

;Stearman 70
;Model 73
;Stearman 75
;Stearman 76

Other designations

;Stearman XPT-943
;Stearman Kaydet
;American Airmotive NA-75

Operators

;

Surviving aircraft

A considerable number of Stearmans remain in flying condition throughout the world, as the type remains a popular sport plane and warbird.

Argentina

Australia

  • 75-6488 – B75N1 registered as VH-EYC, airworthy, owned by Steven Bradley, South Australia 5134
  • 75-7462 - B75N1 - registered as VH-PWS, airworthy, owned by Michael Murphy, Royal Aero Club of Victoria.
  • 75-8314 – E75 Registered as VH-USE, airworthy, owned by Raalin, Western Australia 6208

Austria

  • 75-2606 – Registered as OE-CBM, airworthy
  • 75-5032 – PT-17 Registered as OE-AMM, airworthy at Hangar-7, Salzburg

Brazil

Canada

Colombia

  • FAC-62 – PT-17 airworthy
  • FAC-1995 – PT-17 airworthy

Iceland

  • T5-1556 – PT-17 is airworthy with Erling Pétur Erlingsson in Hafnarfjörður, Capital Region. It is the oldest airplane in Iceland. It was brought to the country in 1941 by the aircraft carrier and damaged in an accident in 1943.

Indonesia

Israel

Mexico

Netherlands

New Zealand

  • 75-647 – PT-17 airworthy with R. J. S. Jenkins in Ardmore, Auckland.
  • 75-2055 – PT-17 airworthy with R. B. Mackley in Milford.
  • 75-2100 – PT-17 airworthy with Classic Aircraft Sales Limited in Blenheim.
  • 75-2724 – PT-17 airworthy with B. L. Govenlock in Hastings.
  • 75-3132 – PT-17 airworthy with the Antonievich Family Trust in Pukekohe.
  • 75-3655 – PT-17 airworthy with M. P. Cantlon in Mount Maunganui.
  • 75-4245 – PT-17 airworthy with the Strome Farm Trust in Drury.
  • 75-5064 – PT-13D airworthy with the Stearman Syndicate in Drury.
  • 75-5907 – PT-13D airworthy with Stearman 03 Limited in Mount Maunganui.
  • 75-8025A – N2S-3 airworthy with M. J. Dean in Mount Maunganui.

Peru

Spain

Switzerland

  • 75-5436 – PT-13D is airworthy, registered as HB-RBG, and based at the Fliegermuseum Altenrhein. Built in 1943 and restored to airworthiness in 1989 after sustaining considerable damage during an emergency landing in the grounds of the Stadler Rail factory in Altenrhein due to engine failure.

Taiwan

United States

In popular culture

Videography

  • Stearman, Lloyd. Stearmans, You Gotta Love Them. Lap Records, 2005.