Boeing-Stearman Model 75 Kaydet

Updated: October 2026 – A deep, rich rumble, a round radial engine, bright yellow wings and maybe even a person standing on top of the wing: when a biplane performs like that at an airshow, it is very often a Boeing-Stearman Model 75, better known as the Stearman or Kaydet. In World War II, tens of thousands of American pilots learned to fly on it. Today it is among the most common flying vintage aircraft of all. On this page you’ll learn how the Stearman came about, what is behind the many designations, how to tell it from the Tiger Moth and Jungmann, and where you can meet it in Europe.

What is the Stearman?

The Stearman is a single-engine trainer biplane with two open seats in tandem. In the old days the flight student sat in front and the instructor behind – or the other way around, depending on the stage of training. It is powered by an air-cooled radial engine: on the most common version, the PT-17, this is a Continental R-670 with about 220 hp, on the PT-13 a Lycoming R-680. This very engine makes the Stearman unmistakable: instead of a slim nose, you see a round ring of cylinders up front.

With a wingspan of just under ten meters and a takeoff weight of about 1.2 tonnes, it is large and heavy for a trainer biplane. The construction is robust: a fabric-covered fuselage of welded steel tube, wings with wooden spars and fabric covering, and a strong main landing gear with cantilever struts. That sturdiness was intentional – a primary trainer has to shrug off hard landings, and training produced plenty of them.

The type was built by Stearman Aircraft in Wichita, Kansas. The company became a Boeing subsidiary in 1934, which is why the aircraft is officially called the Boeing Model 75. The Wichita plant later built bombers such as the B-29 and the B-52 and is now part of Spirit AeroSystems. In the Boeing type family, the Stearman thus sits alongside the airliner Boeing 247 and the B-17 in time.

Origins: from the Model 70 to the Kaydet

The roots go back to the early 1930s. At Stearman Aircraft in Wichita, the Model 70 was created, a biplane designed specifically for basic training, with a Lycoming radial engine of about 210 hp. The prototype flew in 1934 – sources give different dates – and was then evaluated by the Army and Navy.

The US Navy was the first to buy and ordered a version with a Wright radial engine as the NS. For the Army, the Model 75 was developed, entering service in 1936 as the PT-13. That fixed the basic form: until production ended in 1944, little changed on the airframe, and mainly the engine was swapped – depending on which manufacturer could deliver at the time.

In World War II the demand for pilots exploded, and with it production. Wichita delivered trainers at a pace unprecedented for a small biplane: on July 27, 1944, the 10,000th primary trainer left the plant, although spare parts in aircraft equivalents were also included in that count. As complete aircraft, 8,584 units of the Models 70, 75 and 76 are usually cited. Depending on the source and method of counting, you will also find figures above 10,000 – the difference is explained by the spare parts.

The versions at a glance

Version	User	Notable feature
Model 70	Evaluation	1934 prototype with Lycoming radial engine
NS (Model 73)	US Navy	First production version with Wright radial engine
PT-13 / PT-13A–D	US Army	Lycoming R-680, the PT-13D with almost 800 built
PT-17 / PT-17A	US Army	Continental R-670, most common Army version with almost 3,000 built
PT-18	US Army	Jacobs radial engine, only 150 built
PT-27	Canada	About 300 aircraft for the Canadian air force
N2S-1 to N2S-5	US Navy	Various engines depending on sub-version, N2S-3 with 1,875 built
Model 76	Export	Armed export version, e.g. for Latin America and the Philippines

Besides the USA and Canada, Stearmans flew with numerous air forces, including in Argentina, Brazil, China, Greece, Israel, Mexico and Yugoslavia. In the US Navy the yellow trainer had the nickname “Yellow Peril,” derived from its all-yellow livery. With the change of US designations in 1948, the remaining Army aircraft briefly ran as T-13 and T-17. How US military aircraft are marked is explained in the article on US military serials.

After 1945: crop duster, sport aircraft, airshow star

After the war ended, thousands of Stearmans were surplus and were sold cheaply to civilians and former military pilots. That began their second career – and it is the reason so many have survived today.

• Agricultural flying: Many aircraft were converted into crop sprayers. The front seat made way for a tank for fertilizer or pesticide, with a pump and spray boom added. The robust airframe and the forgiving slow-flight characteristics were a perfect fit. According to common figures, around 2,100 Stearmans flew as agricultural aircraft after 1945.
• More powerful engines: A popular conversion was fitting a Pratt & Whitney R-985 Wasp Junior with a variable-pitch propeller. This produced far more capable aircraft.
• Sport and aerobatics: As a sport aircraft and at airshows, the Stearman found a new audience – with aerobatics and spectacular wingwalking displays.

The Super Stearman with a strengthened engine in particular is an airshow classic today. The British company AeroSuperBatics, which has operated the Breitling Wingwalkers and the Utterly Butterly wingwalkers, among others, has toured airshows since 1984 and by its own account flies Super Stearmans with 450 hp. The front cockpit there no longer has controls so the wingwalkers can climb onto the upper wing, and an additional pair of ailerons on the upper wing, coupled to the lower ones, provides faster roll rates. The overview of Europe’s aerobatic teams introduces further teams and displays in Europe.

How to recognize the Stearman

At a fly-in, several biplanes often stand side by side. Four observations are enough to identify the Stearman with confidence.

For the livery, you often find the historic colors: yellow wings with a blue fuselage in Army style or all yellow in Navy style. Many aircraft carry repainted military numbers; the civil registration is then smaller on the fuselage or tail. Stearmans registered in Germany fall into the D-E class because of their mass under two tonnes, as the article on German aircraft registrations explains; Swiss aircraft carry an HB registration. You’ll find general tips for identifying vintage aircraft in the guide Recognizing vintage aircraft in the sky.

Stearman, Tiger Moth, Jungmann or T-6?

The finder helps you narrow it down when several historic trainers stand in front of you.

The Antonov An-2 is much larger: it is also a biplane with a radial engine, but has an enclosed cabin for a dozen passengers. The DHC-1 Chipmunk, the British successor to the biplane trainers, is by contrast a low-wing aircraft with a sliding canopy.

Where to see Stearmans in Europe

The Stearman is rarer in Europe than in the USA, but regularly in the air. Many aircraft came to Europe through the used market from North America or from South American air force inventories and now fly with private owners, clubs and flying collections.

Place	What to expect	Note
Altenrhein Aviation Museum, Lake Constance	HB-RBG (Boeing E75/PT-13D), built in 1943 and delivered to the Argentine navy, flies at displays and events	the first flying Stearman in Switzerland since 1989
Hangar-7, Salzburg	PT-17 Stearman in the Flying Bulls collection	Lineup changes, aircraft are sometimes away
British airshows	Super Stearmans with wingwalkers from AeroSuperBatics, home base Rendcomb	Appearances depend on the season and event calendar
Vintage fly-in Hahnweide	Large gathering of historic aircraft in Baden-Württemberg	Biplanes are welcome there, but a Stearman is not guaranteed

You can learn more about the collection in Salzburg on the page about Hangar-7. Stearmans also fly from smaller airfields in Germany, Austria and neighboring countries – often for sightseeing flights or at airfield festivals. How to find such places and what to look out for there is covered in the article Spotting general aviation. The article Airshows in Europe gives an overview of the major flying displays.

If you travel to the USA, the chances are far better: Stearmans fly at almost every major fly-in there. At EAA AirVenture Oshkosh, historic biplanes stand in large numbers in the Vintage area, and large museums such as the National Museum of the US Air Force show the type in their collections. General planning tips are in the article Plane spotting trip to the USA.

Photo tips for the Stearman

The Stearman is slow, colorful and flies close to the crowd at displays – a rewarding subject.

You can read more about technique at flying displays in the article Photographing airshows. To put into context how rare your encounter really is, use How rare is my sighting?.

Conclusion

The Stearman is the American counterpart to the Tiger Moth: a robust, forgiving biplane on which a whole generation of military pilots learned the basics. Because it was built in large numbers and lived on after the war as a crop duster and sport aircraft, it is one of the most common flying vintage aircraft today. For spotters it is easy to recognize – round radial engine, straight wings, cantilever landing gear – and in Europe it is seen mainly at airshows, vintage fly-ins and flying collections.