Nov 17 2011

Historic Helicopters The Legendary FW61 Posted 13 years 8 days ago ago by Admin

By Brad McNally

Contributing Editor

 

In the 1930s, a German engineer by the name of Heinrich Focke designed and built a cutting edge helicopter more practical and capable than anything previously developed.  This helicopter, the Fw 61, would shatter the existing helicopter world records and help set the standards of performance and control by which future helicopters would be measured.  Ultimately Focke’s ability to continue on with helicopter development was interrupted by World War II and its aftermath; however the Fw 61 was one of the crowning achievements of 1930s rotary-wing development in Europe. 

Professor Heinrich Focke graduated from the Hannover Technical High School in 1920.  In 1924, Focke, along with Georg Wulf and Werner Naumann, formed Focke-Wulf Flugzeugbau AG.  Better known as Focke-Wulf, this company would become one of the largest aircraft manufacturers in Germany prior to and during World War II.  Georg Wulf would not play a major role in the company, as he died in a 1927 airplane accident.  Professor Focke became interested in rotary-wing flight after Focke-Wulf was licensed to build Cierva Autogyros.  Although it is unclear how many Autogyros were actually produced in Germany, it is known that Heinrich Focke became increasingly determined to design a helicopter. 

In a strange turn of events largely influenced by politics, the Board of Directors eventually forced Focke out of his own company.  Hitler had come to power and the German military was expanding.  Heinrich Focke opposed Focke-Wulf mass-producing fixed-wing aircraft for the Luftwaffe, which made him politically unpopular.  After losing his status as the Technical Director at Focke-Wulf, Focke assembled a group of engineers to begin work on a helicopter.  The group eventually developed a three-horsepower, electric model which was used to refine rotor head designs.  Subsequently, a small-scale free flying model of the entire helicopter underwent extensive wind tunnel testing.  Construction on the full-scale helicopter began in March of 1935.

To counter torque effects, the Fw 61 used two rotor heads turning in opposite directions.  The rotor heads were located on steel outriggers extending from the fuselage.  Each rotor head had three fully articulated, fabric-covered rotor blades made of a steel spar and plywood.  To save development time, a Focke-Wulf Fw 44 Stieglitz fixed-wing fuselage was used for the body of the helicopter.  The Fw 44 was a popular two cockpit-training biplane.  A 160 horsepower Siemens-Halske Sh 14E radial engine powered the rotors through a system of gears and shafts.  A small propeller was put in the front of the aircraft, which gave it the appearance of an Autogyro.  However, the propeller provided no thrust and was simply used as a fan to cool the engine behind it. 

The first Fw 61, designated as Fw 61 V1 and registered as D-EBVU, was completed sometime late in 1935.  The building of a second prototype known as Fw 61 V2 began in January of 1936 and finished in early 1937.  Although Heinrich Focke had separated from Focke-Wulf, he was still using the Focke-Wulf wind tunnel and the company’s manufacturing facilities.  Professor Focke would later partner with a well-known aerobatic pilot named Gerd Achgelis to form Focke Achgelis and Company GmbH.  The company was also known as Focke-Achgelis and its aircraft were designated with the prefix “Fa.”  Subsequently, the Fw 61 has also been called the Fa 61.  The aircraft was primarily a creation of Heinrich Focke and was built after he left Focke-Wulf and before Focke-Achgelis was formed.  It has been suggested that the most accurate designation is actually the Focke Fw 61.

Fw 61 V1 began tethered testing late in 1935.  The first free flight was on June 26, 1936.  Ewald Rohlfs was the pilot for the first flight, which lasted less than one minute.  In July of 1936 the Fw 61 received its type certificate in Germany, making it the first certified helicopter.  Another important first occurred on March 10, 1937.  On that day test pilot Ewald Rohlfs took the Fw 61 to an altitude of just over 1,300 feet and switched off the engine.  Rolfs subsequently made the first successful helicopter autorotational landing.  Although Autogyros had proven that this maneuver was entirely possible, Rolf’s power off landing marked an important milestone in helicopter development. 

Over a two-day period in June of 1937 the Fw 61, again with Rohlfs at the controls, would smash five Federation Aeronautique Internationale (FAI also known as the International Aviation Federation) records.  The helicopter would fly for over one hour and 49 minutes, breaking the endurance record of one hour and two minutes; ascend vertically to an altitude of 7,995 feet, besting the previous mark of 519 feet; fly at a speed of 76.1 mile per hour, nearly tripling the previous record of 27.7 miles per hour; cover a closed circuit distance of 50.1 miles, bettering the old mark of 27.8 miles and fly a straight line distance of 10.2 miles, which was over 10 times the previous record of .7 miles.  The Breguet-Dorand Gyroplane Laboratoire held all the previous records. 

The Fw 61 would go on to break two of its own records later in the 1930s.  In 1938, the helicopter vertically ascended to an altitude of 11,247 feet and in 1939 it flew a straight-line distance of 143 miles.  Both Fw 61 prototypes were tested extensively and several new helicopter pilots were trained.  As word of the new helicopter and its capabilities spread, public interest grew.  The Luftwaffe and the Nazi government began to use the helicopters for propaganda.  Both Fw 61s flew at air shows and public events.  The most famous of these demonstrations happened at the Colonial Exhibition in February of 1938.  This event was held at the indoor Deutschlandhalle sports stadium in Berlin.  For 14 consecutive nights a famed German female pilot named Hanna Reitsch flew the Fw 61 V1 inside the enclosed hall demonstrating its capability and maneuverability to the large crowds in attendance. 

Heinrich Focke and Focke-Achgelis would go on to design a second generation of the Fw 61, the Fa 266.  Also known by its military designation, the Fa 223 Drache or Dragon, this helicopter was a larger version of the Fw 61.  The Fa 223 boasted a 1,000 horsepower engine capable of lifting an 80-foot-long fuselage with a four-seat enclosed cabin.  The Fa 223 flew at speeds up to 115 miles per hour and at altitudes up to 23,400 feet.  In total, 18 prototype and production Fa 223s were built before the production facility was bombed during World War II. 

One of the surviving Fa 223s became the first helicopter to cross the English Channel.  The first Fw 61 made its last flight on November 25, 1941 and was later destroyed during a Royal Air Force bombing raid in June of 1942.  The second Fw 61 prototype is last known to have flown on December 18, 1941.  It is believed that the French captured Fw 61 V2 in May of 1945.  However, there are also unconfirmed reports that parts of the second Fw 61 were seen in a German scrap yard after WWII.  Despite leading the world prior to and even during WWII, Germany lost its place at the top of rotary-wing development after the war.  Due to the post-war industrial conditions, Heinrich Focke was unable to continue with helicopter development.  However, his work, especially the Fw 61 prototypes, would set the stage for a decade of rapid growth in helicopter design that was about to unfold in the United States during the 1940s.

The development of the helicopter has been a long process pushed forward in phases by men like Cierva, De Bothezat and Sikorsky.  The length of this process and the incremental nature of rotary-wing developments make it impossible to denote one individual as the inventor of the helicopter.  It is similarly difficult to designate one aircraft as the first helicopter.  Some aviation historians will argue that the Breguet-Dorand Gyroplane Laboratoire was the first real helicopter, while others will say that the Fw 61 was the first practical helicopter.  Which aircraft should lay the rightful claim to being the first?  The Gyroplane Laboratoire was constructed in the early 1930s and did fly in 1935, beating the Fw 61 into the air.  The Breguet-Dorand creation also establishes several FAI records for speed, altitude and endurance while demonstrating good controllability. 

However, less than a year after the Gyroplane Laboratoire took to the sky, the Fw 61 flew and significantly raised the bar for helicopter design and capability.  The Fw 61 was the first helicopter to make an autorotational landing and smashed the altitude and speed records set by the Gyroplane Laboratoire.  The Fw 61 made several cross-country flights and was the first helicopter designated as an approved aircraft by an aviation regulatory agency; it is also generally regarded to have had a higher degree of reliability, control and capability than the Gyroplane Laboratoire.  Regardless of whether or not the Fw 61 should rightly be considered the first actual or practical helicopter, it holds a significant place in helicopter history.

Gablehouse, C. (1967). Helicopters and Autogiros: A Chronicle of Rotating-Wing

Aircraft. Philadelphia: J. B. Lippincott Company.

Heinrich Focke-Fa-61. (n.d.). U.S. Centennial of Flight Commission Website.

http://www.centennialofflight.gov/essay/Rotary/Focke/HE5.htm