Boeing Stearman Model 75, part seven. The Stearman in America, part four. USAAC, USN and USAAF users

 

The Boeing Stearman Model 75 is an American biplane of which 10,626 exemplars were manufactured from 1934 until the mid 1940s. 
It served as a primary trainer for both the United States Army Air Forces (USAAF) and the United States Navy (USN) throughout World War 2. 

During late 1933 Mac Short, Harold W. Zipp and J. Jack Clark, engineers at Stearman Aircraft, took a Lloyd Stearman's design made back in 1931 and added cantilever landing gear and adjustable elevator trim tabs to come up with the Model 70, which was able to withstand +12g  and -9g forces. 
This initial Model 70 was powered by a single 210 hp Lycoming R-680 radial engine and flew for the first time on 1st January 1934, with additional test flights being performed later at Wright Field, Naval Air Station (NAS) Anacostia and NAS Pensacola. The performance pleased the USN and requested a similar model to be built under similar specifications, including a 200 hp Wright J-5 engine. This model was designated as NS-1 by the USN and 41 were ordered, with enough spares to build additional 20 machines.

In 1934 Stearman became a subsidiary of Boeing and therefore its aircraft were known as Boeing-Stearm. It was during the summer of that year when Stearman engineers improved the Model 73 (the internal denomination for the aforementioned NS-1) into the Model X75. This lead to the United States Army Air Corps (USAAC) to evaluate the plane that autumn. The Model X75 was powered either by a 225 hp Wright R-760 or a 225 hp Lycoming R-680. The USAAC accepted the model and ordered in July 1935 26 machines powered with the Lycoming engine, designated at PT-13A (PT stands for 'Primary Trainer') with the USN ordering twenty more. In August 1936 the USAAC ordered fifty PT-13As more with thirty more being ordered in October that same year and twenty-eight more in December. 

On 6th June 1941 the US Government approved the civilian version of the Model 75, designated as Model A75L3 (PT-13) and Model A75N1 (PT-17), with around 60 being sold to civilian flight schools such as Parks College of Engineering, Aviation and Technology, the export market and the many British Flying Training School Program across the USA.

This program was established at the beginning of World War 2, when the United Kingdom recognized the need to train a large number of pilots, so a large number of flying and aircrew training schools were set up across the British Empire and some neutral nations like the USA, where pilots could be trained without the risk of enemy interference. 

The British Flying Training Schools were also set up in the United States from 1941 onwards as a result of the Lend Lease Bill. Seven schools were opened (numbered from one to seven, two in Texas, two in Oklahoma and one in California, Arizona and Florida) and of those, at least five of them were equipped or had the PT-13A/PT-17 in their ranks at some point. 

On 15th March 1941 Boeing delivered its 1000th trainer to the USAAC and the 1001th trainer to the USN. Later, on 27th August 1941 the 2000th trainer was delivered to the USAAC. This feat was followed on 27th July 1944 when the company delivered the 10,000th primary trainer.

After World War 2, thousands of surplus PT-17s were sold to civilians and former military pilots. Many were modified as crop-dusters with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars and nozzles placed below the lower wings. 

Sources:

1st https://en.wikipedia.org/wiki/Boeing-Stearman_Model_75

2nd https://en.wikipedia.org/wiki/British_Flying_Training_School_Program

Boeing Stearman Model 75, part six. The Stearman in America, part three. Even more American users.

 

The Boeing Stearman Model 75 was an American double-winged two-seater trainer that was employed all around the globe. Among its users, we can count the following ones:

• Guatemala: In mid 1943 the Guatemalan Air Corps acquired two PT-17s as a planned expansion for their Air Force.
  
  
• Honduras: On 6th February 1946 the Honduran Air Force acquired ten PT-17 Kaydets (though some sources claim they were just six) for use at their Air School. They were followed by twelve additional PT-13 two years later, in 1948. Anyway, all twenty-two (or eighteen) of them served as trainers for the next fifteen years, until 1963, when they were written off and were gradually replaced by more modern types such as the North American T-28 Trojan.
  
  
• Mexico: In July 1951 the Mexican Navy bought some Boeing Stearman N2S-5 (a variant of the PT-13D designed for use with the US Navy) to replace their Fairchild PT-19 trainers. They were assigned to the Mexican Naval Aviation School, to train their naval aviators. Three years later, in 1954, two additional machines were acquired. The N2S served with the Mexican Navy until 1969 when they were replaced by three Beechcraft Model 45 Mentor.
  The Mexican Air Force (MAF) employed the PT-17 too, having a total of up to 35 units destined to basic training at the Military Aviation School.
  
  
• Paraguay: Allegedly the Paraguayan Air Force employed the Stearman Model 75, however, we couldn't find any graphical evidence or description and only text references, and both the drawing and its data should be considered as speculative.
  
  
• Peru: The Peruvian Aeronautical Corps acquired a total of eighteen Stearman Model A75N1 (a export version of the PT-17), known locally as PT-27 in 1942. They replaced the ageing Italian Caproni Ca. 113. 
  
  
• Venezuela: In 1940 the Venezuelan Military Aviation signed a deal to buy three Stearman A75L3 and five A75B4 machines. The A75L3 being the export version of a regular PT-13A, while the A75B4 was the export variant of the PT-17 with some minor improvements such as an improved engine and provisions for light armament. 
  They also acquired five A76B4 (the export version of the Model 75 with cowled engine upgrade and light armament) in 1941. 
  According to some sources a total of 29 Stearmans served with the Venezuela Aviation, but other sources claim they were just 17. Anyway, they were employed as trainers and their ultimate fate is unknown.
  
  

Sources:

1st https://en.wikipedia.org/wiki/Boeing-Stearman_Model_75

2nd https://es.wikipedia.org/wiki/Anexo:Aeronaves_militares_históricas_de_Honduras#Década_de_1940_(1940-1949) (translated)

3rd https://es.wikipedia.org/wiki/Fuerza_Aérea_Guatemalteca (translated)

4th https://es.wikipedia.org/wiki/Historia_de_la_Fuerza_Aérea_del_Perú (translated)

5th https://es.wikipedia.org/wiki/Fuerza_Aérea_Paraguaya (translated)

6th https://www.facebook.com/SentinelMexico1/photos/a.439533016150357/5214703231966621/?type=3&locale=es_LA (translated)

7th https://www.uswarplanes.net/pt13pt17.pdf (translated)

8th https://maquetas.mforos.com/353330/13018102-stearman-pt-17-venezolano-revell-1-48/ (translated)

9th https://iehap.pe/noticias/avion-stearman-pt-17-nuevo-atractivo-del-iehap/ (translated)

10th https://maquetas.mforos.com/353330/13018164-stearman-a76-b4-y-a75-l3-venezolanos-lindberg-1-48-2-aviones/ (translated)

Boeing Stearman Model 75, part three. The Stearman in Asia.

 

The Boeing-Stearman Model 75 is an American biplane-two seater trainer of the 1930s that was employed all around the world in various countries, among the following Asiatic ones:

• China: In 1942 the United States sold China 150 Boeing-Stearman PT-17 primary trainer (Model A75L5) under the Lend-Lease programme. They were to serve in the trainer role at the Kuomintang Air Force School which was moved to the Lak River airport in Punjab, India (actually the closest military installation of the time that we could find there was RAF Lahore).
  After the end of World War 2, in 1946, the Chinese PT-17s flew over the so-called 'Hump Route' (the Himalayas) and returned to Chinese soil to serve as trainers for students at the Jiangqiao Aviation School. 
  In 1947 the Republic of China Air Force (ROCAF) bought twenty-two additional A75L5s, the first two of which were powered by the Lycoming O-435-11 engine which was considered unsuitable by Boeing due to their lack of horsepower. The ROCAF agreed that the remaining 20 aircraft would be powered by the Continental R-680-4 radial engine which yielded 220 hp of power. 
  Mister Yun Duo, who was the director of the Kuomintang Air Force's Third Aircraft Factory located at Taichung, Taiwan, copied the design of the PT-17 in 1947. 
  This copy was commonly known as CJ-1 (from Chinese 'Chū jiào' - meaning 'Primary Trainer-). These CJ-1s were made out of surplus American material left over by the Americans in Taiwan and they were powered by the Continental engine.
  The CJ-1 flew officially for the first time in February 1948 and was quickly followed by a rapid and steady mass production system, where production was supervised by ROCAF's officials.
  A total of 104 CJ-1s were manufactured and sent to various academies on Chinese mainland, most of which were sent back to Taiwan in 1949 when the Kuomintang evacuated to Taiwan and most of the CJ-1s -and surviving PT-17s- were assigned to the Gangshan Air Force Academy to serve as primary trainers. They remained there until 1958 when they were withdrawn from ROCAF's inventory.
  On the other side, it is known that at least one PT-17 was in service with the People's Liberation Army Air Force at Jiangqiao in 1950, but further details are unknown.
  
  
• Iran: According to some sources, the PT-17 was also employed by the Imperial Iranian Air Force in the 1950s, however we couldn't find any reliable source, so the drawing should be considered as speculative.
  
  
• Philippines: In 1937 (though some sources claim it was one year before or even later), the Philippine Army Air Corps (PAAC) acquired an unknown number of the Stearman Model 73L-1 and L-3 (of which a total of 10 machines were manufactured) and 27 Stearman Model 76D-1 and D-3s (AKA BT-1) which makes a total of 37 Stearmans serving with the PAAC.
  This version was armed, as it was equipped with a defensive machine gun at the observer's position and had provision to carry small bombs under the fuselage. In 1941 they were know to be in service with the 1st (School) Squadron at Zablán Field and the 7th Squadron, at Maniquis Field, of the PAAC, however, given the situation of the PAAC, they were very unlikely to have seen any action when Japan invaded the Philippines in December 1941.
  After World War 2, in 1947 with the creation of the Philippine Air Force (PAF), many PT-17s  were acquired to serve at the PAF's school and even some surviving Model 73s were put into service with that same school. They were kept in service until the mid-to-late 1950s.

Sources:

1st en.wikipedia.org/wiki/Boeing-Stearman_Model_75

2nd http://cwlam2000.epizy.com/cafx82.htm (translated)

3rd http://www.stearman.at/boeing_stearman_technical_data.html