Hans Berger was a Swiss inventor noted for the two successful helicopters that he designed and built by himself with no formal aeronautical training: the BX-50 of 1961 and the BX-110 of 1974. The latter design proved sound enough to earn a certificate of airworthiness from the Swiss Board of Aviation. Besides these two machines, Berger's other inventions were a jet-powered car, and numerous other helicopter designs. Professionally, Berger was the sales representative for Brantly in Switzerland and Liechtenstein.
Unbuilt helicopter projects included:
Berger HB-25 - 4 seat design with turbine power.
Berger BX-111 - 2 seat design with Wankel-type engine and coaxial rotors.
Berger BX-200 - 2 seat design with turbine power.
Berger BX-300 - 3 seat design with stub wings, to be powered by Turboméca turbine.