Anton Flettner was born on November 1, 1885, and died on December 29, 1961. He was a German engineer and inventor who worked on designs for airplanes, helicopters, ships, and cars.

Flettner served in both World Wars. After World War II, he moved to the United States to work as a consultant for the U.S. Navy’s research office.

He studied at Fulda State Teachers College in Germany. From 1906 to 1909, he taught in the village of Pfaffenwiesbach. Later, he taught math and science at a high school in Frankfurt, where he created ideas that helped Germany during World War I.

Flettner invented a new way to use wind power called the Flettner rotor ship. This design allowed ocean ships to use fewer workers and save 90% of their fuel.

World War I

Between 1914 and 1918, Anton Flettner worked for the German Ministry of War on projects to create remote controls for vehicles used in the air, on water, and on land. While working under the guidance of Graf Zeppelin, Flettner also designed plans for pilotless aircraft.

At 29 years old, Flettner introduced his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) during World War I. His second invention, a remote-controlled combat car, was later shown to the Heer (German Army). Both ideas were not accepted because they were not seen as practical at the time. However, Flettner’s work eventually led to the creation of a prototype missile called the Siemens Schuckert Werke 1000 kg wire-guided air-to-surface missile in 1918.

During World War I, Flettner developed a type of control device called the servo tab and anti-servo tab. The servo tab later became the "trim tab," a part still used today on airplanes and large ships. Trim tabs help move large rudders on ships that require less power to operate.

Savonius collaboration

In 1923, a Finnish architect named Sigurd Johannes Savonius became interested in a ship with special rotating sails called a Flettner rotor ship. He worked with the inventor of the ship, and together they developed new ideas. The next year, Savonius created a wind turbine called the Savonius wind turbine. By 1930, he had designed and patented a ventilation device that used the wind turbine's shape. Later, Flettner's company, Flettner Ventilator Limited, bought the patent. This company still makes updated versions of the device in Britain. The ventilation system has been used on buses, vans, boats, railroad cars, campervans, and trucks to help cool the inside during hot weather.

Other post-World-War-I work

After World War I, Anton Flettner became the managing director of the Institute for Aero and Hydro Dynamics in Amsterdam. He held this position until 1931.

With help from scientists and engineers, including Albert Betz, Jakob Ackeret, Ludwig Prandtl, and Albert Einstein, Flettner built an experimental ship called the Buckau. It was later renamed the Baden-Baden and completed in October 1924 at the Friedrich Krupp Germaniawerft. The ship was a schooner that had two rotating 50-foot cylinders added to it. It was the first vessel to use a propulsion system based on the Magnus effect. Flettner had the idea while at the beach with his wife. He used sand moving over his rotating hand to understand the Magnus effect and saw how it could help ships sail. The Baden-Baden crossed the Atlantic in 1926. It could sail faster than normal schooners in moderate to heavy winds but was destroyed by a storm in 1931. Another ship, the Barbara, was also built and sailed to the United States.

In 1926, Flettner focused on aviation by starting his own company, the Anton Flettner Aircraft Corporation in Berlin. He aimed to use the Flettner-rotor as a replacement for wings on large wind turbines. In 1935, he built a German night reconnaissance and anti-submarine autogyro called the Fl 184. He later created the Flettner Fl 185 in 1936, an experimental German gyrodyne that could fly like both a helicopter and a gyroplane.

In 1938, Flettner and Kurt Hohenemser built the Flettner Fl 265. This aircraft was likely the first example of a twin-lift rotor synchropter. It solved the problem of torque compensation and was the first helicopter with intermeshing rotors, known as the Flettner double rotor.

World War II

During World War II, Anton Flettner led a company called Flettner Flugzeugbau GmbH. This company made helicopters for the German Air Force that were used to gather information.

Flettner used money he earned from his ventilator business to fund his helicopter projects. His wife, Lydia Freudenberg Flettner, helped improve the success of this business. Anton Flettner built helicopters for the German military, especially for the navy to spot enemy ships. Even though his wife was Jewish, Anton had a personal connection with Heinrich Himmler, the head of the Gestapo. Himmler arranged for Anton’s wife and family to be safely sent to Sweden during the war. Anton Flettner worked closely with Kurt Hohenemser, an engineer who designed important parts of the helicopters. Hohenemser’s father was also Jewish, but neither he nor his family were harmed during the war as they worked together on helicopter designs.

The final helicopter model, called the Flettner Fl 282 Kolibri ("Hummingbird"), could be made in a factory. However, Anton and Kurt insisted that only they could assemble the complex parts that made the helicopter’s rotors work together. Plans to build 1,000 of these helicopters by BMW were stopped when Allied forces bombed the planned factory.

At least two other helicopters were being developed when the war ended. These included the Flettner Fl 285, a reconnaissance helicopter that could fly for two hours and carry two small bombs, and the Flettner Fl 339, a large helicopter designed to carry about 20 passengers.

Photo gallery

• Flettner Fl 282 Kolibri helicopter
• Letter from Dr. Hohenemser about his connection to Anton Flettner (Page 1 of 2)
• Letter from Dr. Hohenemser about his connection to Anton Flettner (Page 2 of 2)
• The rotor ship "Barbara"
• Flettner's patent for a steering mechanism
• Flettner's childhood home in Eddersheim, Germany. Anton Flettner is on the far right.
• Flettner Fl 282 Kolibri
• Tomb of Anton Flettner
• 1931 photo of the Flettner-Krupp-Grosskraftwagen, the largest German truck at 14 meters long, with a carrying capacity of 15 tons, powered by a 147 horsepower engine.
• Flettner Fl 282 during test flights after World War II, with US markings

Post World War II

After the war ended, Anton Flettner was held at the "Dustbin" interrogation camp at Kransberg Castle. After 1945, Flettner, along with many other people who worked on airplanes, was brought to the United States as part of Operation Paperclip. Flettner and his partner, Kurt Hohenemser, were among the first German people to move to the United States after World War II.

Flettner started a company called Flettner Aircraft Corporation, which designed helicopters for the U.S. military. In 1949, Flettner and Kurt Hohenemser, who had created many patents in Germany, stayed in touch after both moved to the United States.

Flettner’s company in the United States was not commercially successful, but his work was shared with the U.S. Army Air Forces. During his 14 years in the United States, Flettner worked on research projects for the U.S. Army, U.S. Air Force, and U.S. Navy.

Contrary to what many people believe, Anton Flettner never worked for Kaman and had no connection to any helicopters built by the company. Flettner started his own company, Flettner Aircraft, in the United States and spent the rest of his life trying to solve the problem of helicopter main gear life, but he was not successful.

Today, the Flettner rotor is used as an extra power system on transport and research ships. Two ships use a changed version of the Flettner rotor: the turbosail Acyone, created by Jacques-Yves Cousteau in 1985, and the E-Ship 1, a cargo ship that began its first voyage in 2010. Albert Einstein praised the Flettner Rotor ship for its practical importance.

Anton Flettner’s colleague and former partner, Kurt Hohenemser, worked in the United States to prove Flettner’s idea that flexible helicopter-type rotors are better for producing wind energy than rigid airplane-type rotors. An offshore wind energy project announced in February 2017, involving Seawind Ocean Technology B.V., aims to test the wind energy ideas proposed by Anton Flettner, Kurt Hohenemser, and Glidden Doman in challenging wind and sea conditions.

Anton Flettner died at age 76 in New York City on December 29, 1961. He was honored as an honorary member of the American Helicopter Society and the Convertible Aircraft Pioneers. His birthplace home and tomb are protected as important historical sites in Germany.

Aircraft built by Flettner Flugzeugbau GmbH

• Flettner Fl 184
• Flettner Fl 185
• Flettner Fl 265
• Flettner Fl 282
• Flettner Fl 285
• Flettner Fl 339