The Baumgärtl Heliofly III/57 and Baumgärtl Heliofly III/59 were 1940s experimental backpack helicopters designed and built by the Austrian-designer Paul Baumgärtl.
[1] Following on from his earlier experiments with strap-on autogyros the Heliofly III/57 was powered by two 8 hp (6 kW) Argus As 8 piston engines each driving a single-blade of the contra-rotating rotors.
[1][2] A problem with the supply of the As 8 engine forced a re-design to use one 16 hp (12 kW) engine,[1] 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.
[1][2] Data from [1] The Illustrated Encyclopedia of AircraftGeneral characteristics
Related lists This article on an aircraft of the 1940s is a stub.