One blade
Adam
I think the BO-102 was a "hover training device"
I would be very doubtful it would be capable of achieving any speed.
As far as the construction would be:
flap : I can hardly see how a helicopter would be capable of forward flight without cyclic control which means flap...
lead-lag : is a consequence of flap. Since there is no symmetry as there is in a two bladed heli, Coriolis could be a problem depending on the detailed construction.
I think the BO-102 setup is a stiff rotor with one central flapping hinge. This forces symmetry in flapping which is beneficial for Coriolis, but at the expense of bending moments which are 10 times greater than Coriolis forces....
Looks a lot more simple to me to put two blades....