Froebe helicopter

The machine was constructed on a custom-made steel tubular frame using spare parts and equipment from automobiles, farm machinery and elsewhere.

Fitted with a de Havilland Gipsy aero engine, it had twin concentric contra-rotating rotors of stainless steel tubing with fabric covering and with full cyclic and collective pitch control.

In 1927, the Froebe brothers (Nicolas, Theodore and Douglas) purchased and assembled a Heath Parasol fixed-wing aircraft kit and learned to fly.

In the winter of 1936–1937, the brothers traveled to Oakland, California to learn about rotary-wing aircraft and commenced construction of their own helicopter in 1937.

Douglas Froebe moved to California, but returned to Homewood to carry out experiments with another novel aircraft design.