Baumgärtl Heliofly III

The Baumgärtl Heliofly III/57 and Baumgärtl Heliofly III/59 were 1940s experimental backpack helicopters designed and built by the Austrian-designer Paul Baumgärtl. Following on from his earlier experiments with strap-on autogyros the Heliofly III/57 was powered by two 8 hp Argus As 8 piston engines each driving a single-blade of the contra-rotating rotors.

A problem with the supply of the As 8 engine forced a re-design to use one 16 hp engine, powering two rotors on a common co-axial shaft, with the engine driving one rotor directly and the other through gearing to overcome the torque effects.