Dave, and Nick L,. .. .As far as my question about the length of blades, why do Heli rotor blades seem to follow the convention of lots of length plus very little twist, compared with a Prop from a Fixed wing which is shorter wider and has a pronounced twist to create Pull/push power, if the osprey can have a big aircraft type Prop cum Rotor why would this sort of design not be able to be used in other heli configs, which if it could be used would create a far more rigid system, or is it purely down to the osprey type design of prop would then weigh more than would be ecomnomic for the Heli type design?