Anton Flettner

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Anton Flettner
Anton Flettner 01.jpg
Anton Flettner
BornNovember 1, 1885
DiedDecember 29, 1961 (1961-12-30) (aged 76)
Engineering career
Discipline Aviation Engineer, Inventor
Projects Helicopters, Rotor Ships

Anton Flettner (November 1, 1885 – December 29, 1961) was a German aviation engineer and inventor. [1] Born in Eddersheim (today a district of Hattersheim am Main), Flettner made important contributions to airplane, helicopter, vessel, and automobile designs. [1] [2] [3]


After serving Germany in both World Wars, Anton Flettner emigrated to the United States post World War II as a consultant to the office of Naval Research at the United States Navy. [4]

Anton Flettner attended the Fulda State Teachers College in Fulda, Germany. [5] He was the village teacher in Pfaffenwiesbach from 1906 to 1909. [4] Flettner subsequently taught high school mathematics and physics in Frankurt, where he developed ideas that would assist Germany in World War I. [5]

Flettner revolutionized the art of harnessing the wind, used essentially in an unaltered form for thousands of years—the canvas sail—by a modern machine—the Flettner Rotor ship—that could permit ocean liners to reduce their crews by two-thirds and save 90 percent in fuel. [6] [7]

World War I

From 1914 to 1918 Anton Flettner worked at the German Ministry for War in the development of remote controls for air, water, and land vehicles. [8] While employed under the aegis of Graf Zeppelin, Flettner also developed pilotless aircraft projects. [1] [9]

At the age of 29, Flettner presented his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) of World War I. [2] This, and his next invention, a remote-controlled combat car, which was presented to the Heer (German Army), were rejected because they were not considered to be technically feasible. [2] However, Flettner's efforts culminated in the prototype Siemens Schuckert Werke 1000 kg wire guided air to surface missile of 1918. [9]

During World War I, Flettner developed the servo tab / anti-servo tab. [10] The servo tab evolved into the "trim tab" which is still in use on all airplanes and many large vessels. [1] [10] Trim tabs are extremely useful in moving large rudders on vessels with vastly reduced power. [1] [10]

The Flettner rotor ship Buckau Buckau Flettner Rotor Ship LOC 37764u.jpg
The Flettner rotor ship Buckau

Post World War I

Following World War I, Flettner was named Managing Director of the Institute for Aero and Hydro Dynamics in Amsterdam. [4] He held that post until 1931. [4] In the 1920s, Flettner also invented the famous Flettner rotary ventilator, which was widely used on buses, vans, boats, railroad cars, campervans, and trucks to assist cooling without the use of energy. [2] Modern derivatives of his ventilator are still manufactured in Britain by Flettner Ventilator Limited. [2]

With assistance from Albert Betz (German physicist), Jakob Ackeret (Swiss aeronautical engineer), Ludwig Prandtl (German engineer), and Albert Einstein (German theoretical physicist), Anton Flettner constructed an experimental rotor vessel (Buckau later renamed the Baden-Baden) in October 1924 at the Friedrich Krupp Germaniawerft. [11] The Buckau was a schooner refitted with two rotating 50-foot cylinders and was the first vessel built with a propulsion system based on the Magnus effect. [11] Flettner came upon the idea while at the beach with his wife. [7] Flettner used sand, flowing over his rotating hand, to describe the Magnus effect and realized its potential for sail propulsion. [7] The Baden-Baden crossed the Atlantic in 1926. [4] It could outsail normal schooners under moderate to heavy winds, but it was destroyed by a storm in 1931. [12] A commercial ship, the Barbara Rotor ship, was also built and sailed to the United States. [12]

In 1926, Anton Flettner shifted his focus to aviation in founding his own company, the Anton Flettner Aircraft Corporation in Berlin, aiming at the application of the Flettner-rotor as a wing replacement on large wind turbines. [8] [10] In 1935, Flettner built a German night reconnaissance and anti-submarine autogyro called the Fl 184. [10] [13] Flettner followed this accomplishment by building the Flettner Fl 185 in 1936, an experimental German gyrodyne, which could fly as both a helicopter and as a gyroplane. [14]

In 1938 Flettner, together with Kurt Hohenemser, built the Flettner Fl 265. [2] The Flettner Fl 265 as the likely pioneering example of a twin-lift rotor synchropter, addressed the problem of torque compensation as the first helicopter with intermeshing rotors (Flettner double rotor). [2]

Flettner Fl 265 model Flettner Fl265 model.png
Flettner Fl 265 model

World War II

During World War II, Anton Flettner headed Flettner Flugzeubau GmbH, which specialized in reconnaissance helicopters for the German Luftwaffe (Air Force). [1]

Flettner's helicopter inventions were financed from wealth acquired from his ventilator business, a company that was enhanced by the skill of his wife, Lydia Freudenberg Flettner. [2] Anton Flettner built his helicopters for the German military, primarily for navy spotter use. Although his wife was Jewish, [15] he held a personal relationship with the head of gestapo, Heinrich Himmler. Himmler had Flettner's wife and family escorted safely to Sweden for the duration of the war. [15] Anton Flettner's partner and confidant was Dr. Kurt Hohenemser, a brilliant and thorough engineer who developed the details necessary for the success of Flettner's helicopters. [15] Dr. Hohenemser's father was also Jewish, yet both remained unharmed during their tenure together throughout the war as they worked to develop the helicopter for military use. [9] [15]

Flettner Fl 282 "Kolibri" was an early variant of helicopter using two intermeshing rotors Flettner 282 Modell 02.jpg
Flettner Fl 282 "Kolibri" was an early variant of helicopter using two intermeshing rotors

While the final product, the Flettner Fl 282 Kolibri ("Hummingbird"), could be factory-assembled, Flettner and Hohenemser insisted that they were the only ones who were capable of assembling the complex intermeshing rotor gearbox assembly. [1] Plans for mass production of 1,000 Flettner Fl 282 helicopters by BMW were disrupted when allied forces bombed the designated factory. [9]

At least two other Flettner helicopters were under development when World War II ended. [16] They were the Flettner Fl 285, another reconnaissance helicopter with a two-hour flight limit and capacity to carry two small bombs, and the Flettner Fl 339, a large transport helicopter project designed for approximately 20 passengers. [16]

Post World War II

Flettner meets Wernher von Braun Flettner+3(~v braun).jpg
Flettner meets Wernher von Braun

Upon the war's conclusion, Anton Flettner was held in the "Dustbin" interrogation camp at Kransberg Castle. [17] After 1945, Flettner, along with many other aviation pioneers, was brought to the United States as part of Operation Paperclip. [18] Flettner and his partner, Dr. Kurt Hohenemser, were among the first German emigrants into the United States after World War II. [19]

Flettner started Flettner Aircraft Corporation, which developed helicopters for the U.S. military. [1] In 1949, Flettner employed Kurt Hohenemser as a consultant to the Flettner Aircraft Corporation. [20] Flettner and Kurt Hohenemser, who together developed numerous patents in Germany, kept in close contact after both men emigrated to the United States. [20]

Flettner's company in the U.S. was not commercially successful, but his work was shared with the US Army Air Forces. [10] Throughout his 14 years in the United States, Flettner was active in carrying out research projects for the US Army, US Air Force, and the US Navy. [4]

Flettner became the chief designer of Kaman Aircraft and many of the Flettner design concepts are found in Kaman helicopters of later years. [8]

Today the Flettner rotor is in operation as a supplemental propulsion system for transport and research vessels. [21] There are two ships utilizing the concept of the Flettner rotor in a modified form, the turbosail Acyone developed by Jacques-Yves Cousteau in 1985 and the E-Ship 1, a cargo ship that made its first voyage in 2010. [2] [22] [23] Albert Einstein praised the Flettner Rotor ship as having great practical importance. [1]

Anton Flettner's colleague and former partner, Kurt Hohenemser, worked his remaining years in the United States to prove Flettner's idea that properly designed flexible helicopter-type rotors are more suitable for producing electricity from the wind than rigid airplane-type rotors. [19] An offshore wind energy project announced in February 2017, involving Seawind Ocean Technology B.V., aims to demonstrate the wind energy applications put forth by Anton Flettner, Kurt Hohenemser, and Glidden Doman (American aeronautical engineer) in harsh wind and sea conditions. [19] [24] [25] [26]

Anton Flettner died at age 76 in New York City on December 29, 1961. [27] Among his many distinctions, Anton Flettner was an honorary member of the American Helicopter Society and the Convertible Aircraft Pioneers. [4] Flettner's birthplace home and tomb are national historic protected monuments in Germany. [2]

Flettner Rotor Aircraft (The Plymouth A-A-2004) Flettner Rotor Aircraft.jpg
Flettner Rotor Aircraft (The Plymouth A-A-2004)

Aircraft built by Flettner Flugzeugbau GmbH

See also

Related Research Articles

Kaman Corporation is an American aerospace company, with headquarters in Bloomfield, Connecticut. It was founded in 1945 by Charles Kaman. During the first ten years the company operated exclusively as a designer and manufacturer of several helicopters that set world records and achieved many aviation firsts.


Anton Flettner, Flugzeugbau GmbH was a German helicopter and autogyro manufacturer during World War II, founded by Anton Flettner.

Kolibri, meaning hummingbird, may refer to:

Savonius wind turbine

Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting the force of the wind into torque on a rotating shaft. The turbine consists of a number of aerofoils, usually—but not always—vertically mounted on a rotating shaft or framework, either ground stationed or tethered in airborne systems.

Kaman HH-43 Huskie Helicopter with intermeshing rotors in use by the US military from the 1950s to the 1970s

The Kaman HH-43 Huskie was a helicopter with intermeshing rotors used by the United States Air Force, the United States Navy and the United States Marine Corps from the 1950s until the 1970s. It was primarily used for aircraft firefighting and rescue in the close vicinity of air bases, but was later used as a short-range overland search and rescue aircraft during the Vietnam War.

Rotor ship Ship with Flettner rotors as sails

A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large powered vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship that attempted to tap this force for propulsion, and ships using his type of rotor are sometimes known as Flettner ships.

Flettner Fl 282

The Flettner Fl 282 Kolibri ("Hummingbird") is a single-seat intermeshing rotor helicopter, or synchropter, produced by Anton Flettner of Germany. According to Yves Le Bec, the Flettner Fl 282 was the world's first series production helicopter.

Intermeshing rotors

Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted with a slight angle to the other, in a transversely symmetrical manner, so that the blades intermesh without colliding. The arrangement allows the helicopter to function without a tail rotor, which saves power. However, neither rotor lifts directly vertically, which reduces efficiency per each rotor.

Helicopter Type of rotor craft in which lift and thrust are supplied by rotors

A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally-spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL aircraft cannot perform.

Kaman K-MAX American medium-lift helicopter

The Kaman K-MAX is an American helicopter with intermeshing rotors (synchropter) by Kaman Aircraft. It is optimized for external cargo load operations, and is able to lift a payload of over 6,000 pounds (2,722 kg), which is more than the helicopter's empty weight. An unmanned aerial vehicle version with optional remote control has been developed and evaluated in extended practical service in the war in Afghanistan.

Flettner rotor Cylindrical, rotating aerodynamic surface

A Flettner rotor is a smooth cylinder with disc end plates which is spun along its long axis and, as air passes at right angles across it, the Magnus effect causes an aerodynamic force to be generated in the direction perpendicular to both the long axis and the direction of airflow. The rotor sail is named after the German aviation engineer and inventor Anton Flettner, who started developing the rotor sail in 1920s.

Flettner airplane

A Flettner airplane is a type of rotor airplane which uses a Flettner rotor to provide lift. The rotor comprises a spinning cylinder with circular end plates and, in an aircraft, spins about a spanwise horizontal axis. When the aircraft moves forward the Magnus effect creates lift.

Flettner Fl 265

The Flettner Fl 265 was an experimental helicopter designed by Anton Flettner.

Flettner Fl 185

The Flettner Fl 185 was an experimental German gyrodyne developed by Anton Flettner, a machine which could fly both as a helicopter and as a gyroplane.

Kaman K-225

The Kaman K-225 was an American experimental helicopter developed by Kaman Aircraft. One example was modified to become the world's first gas turbine-powered helicopter.

Kurt Heinrich Hohenemser was a German-born American aerospace engineer and pioneer in the field of helicopter design.

Glidden Doman

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The Gamma 60 wind turbine, a 1.5 MW two-bladed upwind horizontal axis wind turbine, was installed by Wind Energy Systems Taranto S.p.A. (WEST) at Alta Nurra, Sardinia, Italy in April 1992. Founded on original research and development work by NASA and Hamilton Standard, the Gamma 60 wind turbine was the world's first variable speed wind turbine with a teetering hinge.


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