Bölkow Bo.46 Experimental Helicopter

The experimental Bölkow Bo.46 helicopter, designed by Bölkow, made its first flight on January 30, 1964. The aircraft’s streamlined fuselage was manufactured by the “SIAT” company. An order was placed for the construction of three prototypes.

This helicopter was primarily intended for testing the innovative Derschmidt rotor, a key component for its performance.

The Innovative Derschmidt Rotor

The Derschmidt rotor belongs to the stabilized rotor type and features a comparatively large, rigid hub. The outer sections of the blades are made from fiberglass. They are attached to five profiled arms of the hub using hinges that compensate for blade deflection in two planes.

Thanks to this design, under the action of the oncoming airflow, the sweep angle of the retreating blade increases, while that of the advancing blade decreases. This significantly raises the limiting Mach number for the airflow around the blade tips, optimizing performance and speed capabilities.

Development and High-Speed Potential

From a technical standpoint, the helicopter proved to be very successful. However, further work on the program ceased in 1966, before the intention to install two Turbomeca Marbore II turbojet engines on the sides of the fuselage could be realized.

Calculations showed that with these additional turbojets, the helicopter would have been capable of exceeding a speed of 400 km/h in flight, representing a significant achievement for its time that unfortunately did not materialize.

Technical Specifications

Modification	Bo.46
Main rotor diameter, m	10.00
Maximum takeoff weight	2000
Engine type	1 Turboshaft Turbomeca Turmo IIIB
Power, hp	1 x 800
Maximum speed, km/h	319
Cruising speed, km/h	261
Crew, crew	2

Image and diagram gallery of the Bölkow Bo.46 Experimental Helicopter

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