Heinrich Focke Fa 61
pilot Hanna Reitsch demonstrated the Fa-61 in the enclosed
Deutschlandhalle sports stadium in Berlin in February 1938.
Heinrich Focke, a German professor who
created the Focke-Wulf airplane company, also began working on helicopters
in the 1930s. Like Louis Bréguet, he performed research on the problems of
control of rotary winged flight and built a scale model helicopter in
1932, before Bréguet flew his craft in 1933. But four years passed before
Focke was to build a full-scale version of his model.
In 1936, Focke, in cooperation with
another German named Gerd Achgelis, developed the Focke-Achgelis Fa 61
(often called the Focke-Wulf 61). The Fa 61 used the fuselage and engine
of a training biplane known as the Focke-Wulf Stieglitz. The Stieglitz was
a popular two-cockpit aircraft that had already earned the Focke-Wulf
company an international reputation. Focke and Achgelis kept the open aft
cockpit of the Stieglitz. They removed the wings and replaced them with
two large three-bladed rotors mounted on tubular steel outriggers on
either side of the fuselage. The outriggers were connected to the forward
fuselage of the aircraft. This configuration made the Fa 61 look
superficially like an autogyro with two rotors instead of one. But the
airplane's propeller blades were shortened, and the propeller provided no
power for forward flight as with an autogyro's forward propeller. However,
the propeller still served as a cooling fan for the 160-horsepower
(119-kilowatt) Siemens-Halske Sh14a radial engine, which powered the two
rotors through a complicated system of gears and shafts.
Like Bréguet, Focke solved the torque
problem by using two rotors turning in opposite directions. But the Fa
61's control system was much more robust. If the pilot pushed the control
stick forward and backward, he could tilt the rotor discs forward and
backward together, causing the aircraft to move in the desired direction.
By moving the stick sideways, the pilot could increase the angle of the
blades on one rotor and reduce it on the other to control the roll of the
craft. The rudder pedals tilted the rotors forward and backward in
opposite directions to control yaw. The Fa 61 had excellent stability and
control and was capable of hovering, going straight up and down, and
forward and backward.
Fa-61 is considered to be the first totally successful helicopter.
The Fa 61 was registered D-EBVU and made
its first free flight on June 26, 1936, piloted by the Focke-Achgelis test
pilot, Ewald Rohlfs. The first flight lasted less than a minute and Focke
allowed only a few more tentative flights before suspending the test
program in order to fine-tune his design. During this time, the Bréguet
aircraft was establishing a number of flight records, but often suffered
damage during the flights.
On May 10, 1937, test pilot Rohlfs took
the Fa 61 to an altitude of 1,130 feet (344 meters) and then pulled back
the throttle to idle the engine. He used its spinning rotors to descend
safely to the ground. This demonstration of autorotation finally proved
that a helicopter would not automatically crash if its engine failed.
Seven weeks later, Focke began another
series of tests and in seven days, Rohlfs broke every previous helicopter
record—most of which were held by Bréguet craft. The Fa 61 made a flight
of one hour and twenty minutes, reached a speed of 76 miles per hour (122
kilometres per hour), flew a distance of 143 miles (230 kilometres), and
ultimately reached an altitude of 11,243 feet (3,427 meters). And unlike
the French aircraft that had completed its tests in late 1936, the Fa 61
did not suffer damage during its flight tests.
Following interest by the Luftwaffe,
Karl Francke, chief test pilot of the Rechlin experimental centre, and
Germany's famed female pilot, 25-year-old Flugkapitan Hanna Reitsch, flew
the Fa 61 in September 1937. Reitsch performed a number of test flights,
breaking several of Rohlfs' previous records.
The Nazi government quickly recognized
the propaganda value of having its famous female pilot fly such an
advanced aircraft. In February 1938, Reitsch flew the Fa 61 for fourteen
consecutive nights inside the huge, enclosed Deutschlandhalle sports
stadium in Berlin. Although Reitsch had less than three hours flying
experience with the aircraft, she was able to manoeuvre it successfully in
front of large crowds. In fact, the heat and humidity produced by the
crowd affected the Fa 61's engine performance.
Focke's Fa 61 was far more manoeuvrable
than Bréguet's aircraft and also could fly for extended periods of time.
Although many consider Bréguet's Gyroplane to be the first real
helicopter, Focke's Fa 61 is considered the most successful early
helicopter. It sufficiently impressed the Nazis that they allowed Focke
and Achgelis to form a new helicopter company and awarded them a contract
for an enlarged version of the Fa 61 that could lift 1,500 pounds (680
kilograms) of cargo.
This new craft, designated the Fa 223
Drache (Dragon), made its first flight by spring of 1940. The
Drache had a 1,000-horsepower (746-kilowatt) engine turning two
triple-bladed 39-foot (12-meter) rotors. It was more than 80 feet (24
meters) wide and 40 feet (12 meters) long and had a four-seat enclosed
passenger cabin. Focke and Achgelis built seventeen prototypes and one
production version before the assembly line was bombed. The Drache
flew at speeds up to 115 miles per hour (185 kilometres per hour), rose to
23,400 feet (7,132 meters), and could transport loads weighing a full ton
at low speeds and altitudes. Several Fa 223s survived the war and one
became the first helicopter to cross the English Channel to England.
The Fa-223 Drache could transport loads weighing a full ton. It survived
World War II.
The Fa 61 was the first extremely
successful helicopter, and the Fa 223 was the largest helicopter in
limited production during World War II. After the Fa 61, the most
important developments took place not in Europe, but in the United States.
The dual counter-rotating rotor design (with the rotors mounted
side-by-side) did not prove long lasting or popular. It did prompt others
to pursue helicopter technology.