Anton Flettner

Anton Flettner taught physics and maths to secondary school students in Frankfurt, and in 1905 took a job at the Zeppelin company.

During World War I, Flettner developed a device that allowed airplane pilots to raise or lower a plane's nose for better control. It evolved into the "trim tab" which is still used on all airplanes. Flettner also made several improvements to military tanks, and he apparently designed a guided torpedo which was never built.

After the war, he was named managing director of the Institute for Aero and Hydro Dynamics, Amsterdam, holding that post until 1931.

In the 1920s, he experimenting in using the Magnus Effect and build a schooner with two tall rotating cylinders.

From 1926 to 1945, Mr. Flettner was president of the Anton Flettner Aircraft Corporation in Berlin.

He built his first helicopter in 1930, which was destroyed during a tethered flight in 1933. Flettner turned his attention to autogyros. He built a craft called the Fl 184, which had full cyclic control that allowed the pilot to tilt the rotor by moving the control stick in the direction that he wanted to fly.

Flettner's initial Fl 184 design was successful design-wise. It flew in 1935 and was due to be evaluated by the German Navy when it, too, was unfortunately destroyed. The inventor added power to the main rotor. He also developed a collective pitch control, which allowed the pilot to increase the pitch of all of the lifting blades simultaneously. Flettner also removed the autogyro's main propeller and replaced it with two smaller propellers on outriggers located on the side. The Fl 185, whose prototype (D-EFLT) flew in 1936 and had a 3-blade main rotor. The centrally-mounted Sh.14A engine drove, in addition to the rotor, two small anti-torque propellers on outriggers each side of the cabin and a large cooling fan in the nose.

In 1937, Flettner began developing the Fl 265. This was a small helicopter. It was called a synchropter because of its rotor configuration, had two counter-rotating rotors set close together and splayed outwards. The rotors intermeshed like the blades of an eggbeater. Flettner received a small production contract from the German Navy in 1938, and the aircraft made its first flight in May 1939. The aircraft proved impressively controllable in flight and was a major improvement over the Focke-Achgelis designs.

In 1940, Flettner debuted an improved version designated the Fl 282 Kolibri (hummingbird).

Flettner designed his craft to carry two people, a pilot and an observer. The pilot sat in front of the rotors in an open cockpit affording good visibility. The observer sat in a single compartment behind the rotors, facing the rear. The observer could spot submarines at sea or troop movements on the battlefield. The Kolibri was one of the first helicopters designed with a clear military mission.

The German Navy (Kriegsmarine) was impressed with the Kolibri and wanted to evaluate its use for submarine spotting. However, critics argued that fighter planes would easily attack the slow-flying craft. In 1941, the Navy conducted an evaluation using two fighter planes to stage a mock attack on a Fl 265. The fighters could not hold the agile craft in their gunsights.

Flettner also demonstrated that the little craft could land on a ship, even in heavy seas. Naval leaders were impressed and, in 1940, ordered several dozen of the craft with the clear intention of mass-producing them. Allied bombing ended production efforts, but 24 of the aircraft still entered service, with a number of them being used for escort service, flying off the gun turrets of ships to spot submarines, and performing resupply missions even in poor weather conditions. The German Army also evaluated this type of aircraft.

The Fl 282 served in the Baltic, North Aegean, and Mediterranean Seas. Plans to build thousands of Kolibris were abandoned after the Flettner factories were bombed by the Allies. Only three of these helicopters survived the war; the rest were destroyed to prevent capture. Two of the survivors went to the United States and Britain, the third to the Soviet Union.

The Fl 282 was designed so the rotor blades and landing gear could be removed and the helicopter stored in a compact area such as the pressure tank of a U-boat. There is no evidence that it was ever used this way. It was intended to search for submarines, and in the fairly clear waters of the Mediterranean, a pilot could see a submerged submarine as deep as 130 feet (40 meters). He could match the speed and course of the submarine and radio the position to the convoy. The pilot could also mark the sub's position with a smoke bomb. But the helicopter was too small to carry weapons, although some tests were conducted with small anti-submarine bombs. There is no good information on the helicopter's actual use during the war.

The Kolibri's intermeshing rotors represented the fourth approach to solving the control and torque problems, after Breguet's stacked coaxial counter-rotating blades, Focke's widely spaced counter-rotating blades, and Sikorsky's tail rotor. The Kaman Huskie, which saw U.S. Air Force, Navy, and Marine service during the 1950s and 1960s, and the Kaman K-Max single-seat aerial crane used this design in the 1990s. The design has not proven to be long lasting or popular. The biggest problems with this design are that the helicopters are slow compared to other types and the rotors endanger people on the ground.

The Fl 282 is most notable for pioneering the Naval use of helicopters, particularly for hunting submarines. However, it would be many years before a helicopter was produced that routinely succeed

In 1940, Hitler 's Kriegsmarine (German Navy) made a request for a naval helicopter for operate from its units. Derivative from the Flettner FL 265, the FL 282 deliveries begun in 1942 and the next year, 20 prototypes were in service. The model demonstrate to be very effective so plans for 1000 units where approved but being a Navy aircraft had little claim on production facilities and they were finally aborted due allied bombs to the BMW and Flettner factories.

32 preproduction aircraft were delivered, and three were taken home as war booty by Russia and the United States.

After 1945, Flettner moved to America and started a new Flettner Aircraft Corporation. Now working for the U.S. military, he built helicopters with improved efficiency and control, including some models big enough to carry troops.

Flettner became president of the Flettner Aircraft Corporation , a research and development corcern. he came to USA soon after World War II as a consultant to the office of Naval Research (US Navy Department).

He was actively engaged in carrying out US government research projects for the Army, Air Force and Navy.