Albert Gillis von Baumhauer (Heerenveen, October October 1891 - Alder, 18 March 1939) was a Dutch aviation pioneer notable for his design of the first Dutch helicopter and the related inventions, in particular the cyclic and collective control and a single rotor design.
In 1910 Von Baumhauer built a biplane glider along with the Six brothers. In 1913 he built a model of a helicopter with two counter-rotating rotors. The helicopter flew but it was not stable enough.
After having completed studies in Delft, Von Baumhauer studied for some time aerodynamics at Göttingen and then went to study at the Technical University of Zürich. There he met professor Theodor von Kármán and mathematician and aviation expert, professor Ludwig Prandtl.
In 1910 Baumhauer joined Spyker car factory and in 1919 he became chief engineer at Van Berkel , where he was responsible for the development of the Van Berkel W-B, a seaplane for the Dutch Naval Air Service. On May 12 of that year he married Johanna Hildegonda Oldenhuis Gratama, with whom he eventually had three children.
After closure of the aircraft division of Van Berkel in 1921, von Baumhauer joined the National Research Centre for Aviation where he was a deputy director for some time. Here he devoted himself to various fields of abiation, especially safety in the air, both in wind tunnel tests and in scientific studies.
In 1924 the British Ministry of Aviation announced a contest on the construction of a helicopter, which contained several severe requirements for that time such as flying a closed circuit with a filght speed of 100 km/h, vertical take-of and climb to up to 600 m and glide and safe landing with a stopped engine. The prize of 50.000 £ attracted many contestors, with end data of May 25 1925, which was later extended by one year. n Baumhauer went straight to work and enrolled in 1924. On 5 November 1924 he founded, together with one of the brothers Six, the First Dutch Helicopter Aviation, in order to accomplish construction and perform the flichts. The helicopter was ready inn April 1925 and the first flight was made in September 1925 by lt. F.H. van Heyst in Soesterberg. On February 10, 1926 Van Heyst managed to keep the machine several meters off the ground for 5 minutes.
After the first test flights, the helicopter was transferred to Schiphol in 1926, where B. Grass and later Peter .J. Six acted as test pilots. British contest had been canceled due to a fatal accident in England, but von Baumhauer continued the experiments until 1930. Several improvements have been made, with the flights also getting better, although they still often had a somewhat indefinite direction. On August 28, 1930 von Baumhauer himself made a half an hour flight. The next day, a hinge bolt of one of the rotor blades failed due to fatigue crack, and the helicopter fell on the ground. It helicopter was completely destroyed but von Baumhauer was unharmed. Since the money almost run out, the machine was not rebuild, but on Baumhauer's interest in helicopter development continued to until the end of his life.
Von Baumhauer's design made some major achievement which greatly influenced further development of helicopters. It used a single rotor, as opposed to two counter-rotating rotors on which most contemporary designs were based. He was one of the first to use the tail rotor to counteract the torque produced by the main rotor. The tail rotor was powered by its own engine (for easier control) and its angle of incidence could not be adjusted during flight. Another notable achievement was use of collective and cyclic pitch control. The the swashplate principle was applied. Below the rotor, two concentric rings were mounted, connected to each other with bearings. The non-rotating inner ring coulf be tilted and moved along the rotor shaft. The outer ring rotated with the rotor and adjusted blade angles via rods. This enabled to adjust blade pitch according to blade's current angle, a mechanism which is still used in modern helicopters.
In 1937 von Baumhauer was appointed ad engineer at the Civil Aviation Administration of the Ministry of Public Works, where his tasks included testing and inspection of new aircraft types. In March 1939 he went on a study trip to the United States, where he was killed in the accident with the prototype of the four-engine Boeing Stratoliner airliner in Aider, Washington state. At the time of his death, nomination was ready for his appointment as professor at TU Delft. He also found widespread recognition abroad and was appointed as a Fellow of the Royal Aeronautical Society, corresponding member of the Deutsche Akademie für Luftfahrtwissenschaften and representative of the Netherlands for the Daniel Guggenheim Fund (USA), responsible for aviation safety.
