B472

OTHER: Helicopter - Outside - Single-Bladed Rotor - Complete Rotorcraft

Bolkow:

Boelkow built eighteen Bo-102 "Heli-Trainers". It also built one Bo-103 that was very stable and could be flown hands-off for a few seconds.

The Bo-102 had a twenty-one foot counterbalanced fiberglass rotor blade.

The B0-103 achieved a speed of 90 km/hr in forward flight. It had a GW of 860 lbs., An EW of 590 lbs. And an 80 hp engine, but it was questionable if it could actually produce the 80 hp.

At Outside Web Sites:

http://avia.russian.ee/helicopters_eng/bo-102-r.html

http://www.luftfahrtmuseum.com/htmi/itf/bo102.htm

Conversation with Richard Sohn (February 21, 2006):

He worked at Bolkow on the controls for the Bo-103 flying version.

The attraction was the efficiency of a single-bladed rotor.

The problem was that of vibration.

Some more comments specifically about the B0-103;

The biggest proble was the torque induces vibration.
The blade's CG and the counter weight's GG were, together, balanced about the pitch axis.
The blade and the counter-weight arm were separate items so that adjustments could be made to balance etc.
The blade was restrained from flapping (teetering).

Additional information:

From the book 'Pioneering with Igor Sikorsky';

"Some time during 1946, according to Michael Buivid, a single blade rotor was tried out quietly, and never made public, on a production R-4. This was, of course, the very original concept of Igor's, as being the optimum form of simplicity possible for a helicopter with a main lifting rotor. ....... The R-4 tests were both disappointing and inconclusive, and were therefore quietly forgotten. Actually, as Michael said, trying to match a single-bladed rotor, using the same total blade area at the same rotational speeds, was like comparing apples with oranges. As might be expected, vibration was the outstanding problem associated with trying to design an appropriate counterbalance to the single blade, both aerodynamically and centrifugally." [Source ~ HP p.208]

Michael Gluhareff's patent 2,475,318 dated of application Feb 2, 1945 assigned to United Aircraft may be related to this.

For additional information on single blade rotors see binder, which contains [SBT] etc.

Lidak:

http://www.lidak.it/ ~ It is italian and regurarly flying. It has several patent since it has solved all problem connectet to single bladed rotor. I know mr lidak personally and he 's a genius! This copter is power with two Moto Guzzi fuel injected engines and now he's planning to produce it. It has also a revolutionaty variable idraulic power trasmission to tail rotor.