The brothers Henri (1879-1980) and Armand (1883-1941) Dufaux started their aviation activity at the beginning of 1900s. Their talent as mechanical builders is attested by the fact that they patented a light gasoline engine which could be applied to bicycles. Much later this invention evolved and they started the production in series of motorcycles. The two brothers founded the company H & A Dufaux & Cie and produced the famous Moto-sacoche, a trademark which is still widely known especially among the old-timer motorbike collectors.
Both were greatly interested in aviation and decided (as many other in the world) to build a flying machine. After a series of studies and experimentations they decided to start the construction of a helicopter model. The latter had two biplane rotors in tandem with a diameter of 2 meters and was powered by a two cylinder 2.6/3.5 kW/hp air cooled gasoline engine weighting 4.5 kg. The model, weighting 17 kg altogether, was officially presented in public in Geneva between the 13 and the 17 of April 1905. It rose in the air restrained by cables surrounded by the astonished audience. A month later the helicopter was again presented in France in the huge balloon hangar of the French Aero Club in Coteaux de Saint-Cloud. The flights were witnessed by some of the most important aviation pioneers, such as the famous Brazilian Alberto Santos-Dumont. The latter built in that same year a similar helicopter known as the Santos-Dumont N° 12. However it is almost impossible to know if he was inspired by the Swiss model.
Both demonstrations were a great success and Henri and Armand received a lot of praises. The aviation committee of the French Aero Club considered that their model was a great step towards the development of the helicopter.
These exhibitions were followed by the construction of a real size aircraft. Theoretically the new flying machine was capable to take off vertically like a helicopter and then fly like an airplane. This tilt-rotor prototype was tested during the Summer of 1909 but as many other contemporary aircraft it was incapable to fly and therefore it was abandoned. Before the end of the year our pioneers founded the first Swiss company to produce airplanes. With the biplane Dufaux N° 4 Armand flew over the Léman lake on August 28, 1910 covering a distance of 80 km in 1h18min.
Despite this great success the two brothers did not continue their activity. In 1911 after the production of a limited series of airplanes they decided to sell their aviation company.
Their Dufaux helicopter model is today exposed in Paris in the National Conservatory of Arts and Crafts along with other historical inventions. The original support of the model helicopter along with a Dufaux 4 biplane is nowadays preserved in the Swiss Transport museum located in Lucerne.  

HAB 03/2010