Unusual Rotorcraft - Historic Bolkow 46

Derschmidt - Lagging Blade Rotor

FROM RAR Newsgroup

Bob Barbanes and RW Walker supplied some additional info (to that from the Museum below). This included:-

each blade could move forward and backward to a max of 40 degrees,
the blades had large couterweights inboard creating a pendulum effect,
the blades would 'oscillate' (lead/lag) in harmony with the rotor speed
the leading blade retreated while the retreating blade advanced
the forward backward movement was balanced by the counter weights
the hub was semi-rigid (not unlike the Bolkow 105)

FROM BOLKOW MUSEUM
Bolkow Developments KG started operations in 1956 on several new rotor systems for helicopters.
In the main they concentrated development on a high-speed rotor with controlled lagging, The "Derschmidt" System, which was tested in the Bolkow-46 experimental helicopter. Wind tunnel tests of model rotors showed that this rotor system would enable airspeeds of over 500 km/h, without impairing the normal characteristics of helicopters (hovering flight and high agility).
To test this rotor system, three experimental helicopters with the type designation Bolkow BO-46 were built. The first went into flight testing in 1964. The main engine was a shaft turbine, the Turbomeca Turmo IIIb with 800 WPS take-off power.
The transmission for main and tail rotor were developed by the gear factory Friedrichshafen AG, while the body, including cab and cowl were developed by Siebelwerken ATG., Donauwoerth.
The BO-46 had a flying weight of something over 2000 kg and should have with two additional thrust engines, achieve speeds of over 400 km/h.
The diameter of the main rotor was 10m, that of the tail rotor, 1.8m.
Both rotors consisted of glass-fiber reinforced plastic. Technical difficulties in overcoming disturbing oscillations in the rotor system led to cessation of development and a prototype was transferred to the helicopter museum.

(Link courtesy of terra from RAR)

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D.Marker email: dmarker@internetage.com

Created: 04 Apr 2000 - Updated: 10 Apr 2000