Boeing-Stearman Model 75

Model 75 (Stearman Kaydet)
Boeing Stearman N7058Q in U.S. Navy markings
Role Biplane trainer
Manufacturer Stearman Aircraft / Boeing
Introduction 1934
Number built 8,584 (includes model 70, 75 and 76)
Variants American Airmotive NA-75

The Stearman (Boeing) 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 (as the NS and N2S), 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

A WAVE in a Boeing Stearman N2S United States Navy training aircraft
United States Navy N2S-2 at NAS Corpus Christi, 1943
United States Navy NS-1s of the NAS Pensacola Flight School, 1936
Boeing Stearman E75 (PT-13D) of 1944
Vintage Boeing-Stearman Model 75, Breitling SA
Boeing Stearman (PT-13D) of the TALOA in Dirgantara Mandala Museum, Indonesia
Boeing Stearman (PT-13) of the Israeli Air Force
United States Navy N2S ambulance at NAS Corpus Christi, 1942
Boeing Stearman PT-17, Museum of Historical Studies Institute of Aerospace in Perú – Lima
PT-17 "Kaydet" on display at the Museum of Aviation, Robins AFB
Boeing Stearman PT-17 Kaydet – Aeronautics Museum of Maracay

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 additiional 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 (PT-13) and Model A75N1 (PT-17), 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 Red Baron Stearman Squadron.

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-13A Model A75 with R-680-7 engine, 92 delivered from 1937 to 1938.
PT-13B R-680-11 engine, 255 delivered from 1939 to 1941.
PT-13C Six PT-13Bs modified for instrument flying.
PT-13D Model E75 with R-680-17 engine, 793 delivered
PT-17
Version with Continental R-670-5 engine, 2,942 delivered.
PT-17A 136 PT-17s modified with blind-flying instrumentation.
PT-17B Three PT-17s modified with agricultural spraying equipment for pest control near army bases.
PT-17C Single PT-17 conversion with standardized Army-Navy equipment.
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-18A Six PT-18s modified with blind-flying instrumentation.
PT-27
USAAF paperwork designation given to 300 D75N1/PT-17 aircraft supplied under Lend-Lease to the Royal Canadian Air Force.

US Navy designations

NS
Up to 61 Model 73B1 delivered, powered by 220 hp (160 kW) Wright J-5/R-790 Whirlwind radials
N2S
Known colloquially as the "Yellow Peril" from its overall yellow paint scheme.
N2S-1 Model A75N1 with Continental R-670-14 engine, 250 delivered.
N2S-2 Model B75 with Lycoming R-680-8 engine, 125 delivered in 1941.
N2S-3 Model B75N1 with Continental R-670-4 engine, 1,875 delivered.
N2S-4 Model A75N1 with Continental R-670-4 and -5 engines, 457 delivered of 579 ordered, including 99 PT-17s diverted from U.S. Army orders.
N2S-5 Model E75 with Lycoming R-680-17 engine, 1,450 delivered.

Company designations

Stearman 70
Company designation for prototype, powered by 215 hp (160 kW) Lycoming radial engine, designated XPT-943 for evaluation
Model 73
Initial production version, 61 built for U.S. Navy as NS plus export variants
Model 73L3
Version for the Philippines, powered by 200 hp (150 kW) R-680-4 or R-680C1 engines, seven built
Model A73B1
Seven aircraft for Cuban Air Force powered by 235 hp (175 kW) Wright R-790 Whirlwind, delivered 1939–1940
Model A73L3
Improved version for the Philippines, three built
Stearman 75
(or X75) Evaluated by the U.S. Army as a primary trainer, the X75L3 became the PT-13 prototype. Variants of the 75 formed the PT-17 family.
Stearman 76
Export trainer and armed version of the 75 with a gun ring and one or two fixed forward firing machine guns.
A76B4
5 built for Venezuela.
A76C3
15 built for Brazil.
B76C3
15 built with cameras for Brazil.
76D1
16 built for Argentina and three for Philippines as BT-1.
S76D1
seaplane version of 76D1 for Argentina
76D3
24 built for Philippine Constabulary as BT-1 armed advanced trainer, and 24 built for Cuba.

Other designations

Stearman XPT-943
Designation assigned to the X70 evaluated at Wright Field
Stearman Kaydet
Name used for aircraft in Royal Canadian Air Force service
American Airmotive NA-75
Single-seat agricultural conversion of Model 75, fitted with new, high-lift wings

Operators

Argentina
Bolivia
Brazil
Brazilian Air Force Model A75L3 and 76.
Canada
Royal Canadian Air Force received 301 PT-27s under Lend Lease.
Republic of China
Republic of China Air Force received 150 PT-17s under Lend-Lease, and 104 refurbished aircraft post war in Taiwan. The ROCAF used them until 1958.
Colombia
Colombian Air Force
Cuba
Dominican Republic
Greece
Guatemala
Honduras
Iran
Imperial Iranian Air Force
Israel
Israeli Air Force purchased 20 PT-17s.
Mexico
Mexican Air Force
Nicaragua
Nicaraguan Air Force
Paraguay
Paraguayan Air Force
Peru
Peruvian Air Force
Philippines
Philippine Army Air Corps
Philippine Air Force
United States
United States Army Air Corps/United States Army Air Forces
United States Marine Corps
United States Navy
Venezuela
Venezuelan Air Force
Yugoslavia
Yugoslav Air Force

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

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 USS Wasp 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

  • PT-17 is on display at the Instituto de Estudios Históricos Aeroespaciales del Perú, Miraflores, Lima.

Spain

  • PT-13 on display at the Fundación Infante de Orleans in Cuatro Vientos, Madrid.
  • PT-17 on display at the Fundación Infante de Orleans in Cuatro Vientos, Madrid.

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

Boeing-Stearman NS2-S at the Arkansas Air & Military Museum in Fayetteville, Arkansas
Boeing-Stearman Kaydet at the Air Zoo
Boeing Stearman at the Cavanaugh Flight Museum
Boeing Stearman at the College Park Aviation Museum

Specifications (PT-17)

3-view line drawing of the Boeing N2S-3
3-view line drawing of the Boeing N2S-3

Data from United States Military Aircraft since 1909

General characteristics

  • Crew: 2
  • Length: 24 ft 9 in (7.54 m)
  • Wingspan: 32 ft 2 in (9.80 m)
  • Height: 9 ft 8 in (2.95 m)
  • Wing area: 298 sq ft (27.7 m2)
  • Empty weight: 1,931 lb (876 kg)
  • Max takeoff weight: 2,635 lb (1,195 kg)
  • Fuel capacity: 46 US gal (38 imp gal; 170 L)
  • Powerplant: 1 × Continental R-670-5 7-cylinder air-cooled radial piston engine, 220 hp (160 kW)
  • Propellers: 2-bladed fixed-pitch propeller

Performance

  • Maximum speed: 124 mph (200 km/h, 108 kn)
  • Cruise speed: 96 mph (154 km/h, 83 kn)
  • Service ceiling: 13,200 ft (4,000 m)
  • Time to altitude: 10,000 ft (3,000 m) in 17 minutes 18 seconds
  • Wing loading: 9.9 lb/sq ft (48 kg/m2)

In popular culture

An iconic movie image is a Stearman cropduster chasing Cary Grant across a field in North by Northwest (the airplane that chased Grant was actually a Naval Aircraft Factory N3N Canary; the plane that hits the truck is a Stearman). A heavily modified PT-17 variant was used as the Tornado in the Sonic The Hedgehog 2 Film.

See also

Aircraft of comparable role, configuration, and era