Flettner Fl 265

History

The Flettner Fl 265 served as an experimental helicopter system for the German Navy during World War II. In many respects, the Germans were ahead on multiple military fronts at the time, and helicopters were no exception. Although very few Fl 265 examples were eventually built, the type nicely laid the groundwork for the much-improved Flettner Fl 282 helicopter to come. Both designs were the brainchild of Anton Freitner, a German aerospace engineer and inventor with World War I military experience.

During World War II, Flettner headed the offices of Anton Flettner, Flugzeugbau GmbH, focused on the development and construction of rotorcraft.

Flettner flew his first gyroplane in 1932 and continued to develop his ideas through his fledgling company. His first helicopter design was a massive two-blade machine powered by a 30-horsepower Anzani engine with a 100-foot-diameter rotorthe aircraft was aptly called the "Giant." The first flight was made with a successful launch, and although she remained strapped to the ground for safety reasons, she was quickly disoriented when a gust of wind carried her back to Earth. By 1935, Flettner showed his Fl 184 gyroplane, which was powered by a 150-horsepower Sh 14 radial piston engine. By this time, the German Navy had already taken an interest in Flettner's equipment and requested an evaluation of the Fl 184. Unfortunately, the Fl 184 was lost in an accident before the demo began.

The next interesting Fl 185 followed, flying for the first time in 1936 with three rotors - the main rotor in the center of the cockpit space, and a pair of smaller outboard motors on strut mounts. From there, Flettner elaborated on the idea of ??a counter-rotating meshing rotor system in the Fl 265.

The German Navy led the development of the Fl 265 and ordered six such examples in 1938. Recognizing the potential battlefield value of the kind of hover system developed by Freitner, they argued that the German Navy could deploy these small one-man systems on their surface ships, or even use specially modified submarines, to provide the most important "Eye of the Sky", seeing the enemy's situation at sea for the first time. In turn, it can be used effectively against warships and submarines.

The Fl 265 first flew in May 1939.

Further evaluation of the Fl 265 followed and proved promising enough until the German Navy began to consider the idea of ??producing the Flettner system. However, Flettner's company is already working on an improved version - the Fl 282 - a two-seater creation with improved features and mission versatility. Because of this, RLM delayed the production contract for the Fl 265 and decided to wait for the improved Fl 282 to enter service.

To advance the project, funds and manpower were diverted to the Fl 282 project - effectively ending the Fl 265's short-lived legacy, as only six complete examples were built at the end of its operation.

Externally, the FL 265 used an aircraft fuselage with an open front radial piston engine. The cockpit is amidships, below the rotor mast area, with framed side windows and windshield. The fuselage tapers to a shortened empennage with a rounded large-area vertical fin and smaller low-mounted fins on each rear fuselage side. The landing gear consists of two single-wheeled main landing gear legs and a small tail wheel located at the rear. The main legs are remote from the fuselage by an intricate series of interconnected struts.

Each twin-blade rotor is attached to an identifiable raised structure on the top of the cockpit and operates in unison in a manner known as "mesh." The concept proved to be a pioneering attempt at "synchronized helicopters" - using two separate rotors spinning in opposite directions to achieve lift. This also helps counteract torque, the natural pull created by an engine with externally mounted rotating blades.

Helicopters using counter-rotating blades therefore do not use tail rotors as they are used to counteract the torque effects caused by a single main rotor. A modern example is the Kamov Ka-50 "Black Shark" attack helicopter, which has main rotors stacked on top of each other, so there is no tail rotor.

The Fl 265 is powered by a single Bramo Sh 14A 7-cylinder radial piston engine that delivers approximately 160 hp and can reach a top speed of 99 mph. The aircraft retains an empty weight of 1,764 pounds for a gross weight of 2,205 pounds.

Each rotor is approximately 40 feet and 4 inches in diameter.

Further development and production of the Fl 265 was abandoned in favor of the more promising Flettner Fl 282.

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