Curtiss-Bleecker Helicopter

American engineer, Virginian M. B. Bleecker idea of a rotor driven by airscrews on the blades differed from the others in that his airscrews did not have individual engines but were connected by gearing and chains to a single central Pratt and Whitney 420hp radial power unit.
As constructed by the Curtiss Wright Corporation in 1926, each of the wing-shaped blades had auxiliary trailing strut-mounted control surfaces which, when operated collectively, were to make the aircraft rise or descend, and when operated differentially, to ensure stability. The landing gear consisted of three fixed wheels.
This helicopter successfully made a few "hops" inside the hangar where it was built, but it was abandoned because of its lack of stability and the failure of attempts to eliminate vibration.

Curtiss-Bleecker
Engine: 1 x Pratt and Whitney, 420hp
Rotor diameter: 14.42m
Gross weight: 1500kg
Number of seats: 2