Slowrotor,
2P will happen everytime the cyclic is moved off-centre. Models get away with it because they carry no useful payload (and bending moments don't scale linearly) - so structure can withstand the vibration. The batteries don't scale up too well either.
Dave,
Interesting concept. My first thought would be why even allow hub compliance, if the gyro is there to remove 2P vibration. The only advantage i can think of is the convenient hangerage of a 2-blader. Probably once the gyro mass was taken into account, an additional blade or two works out lighter. Then again the hub compliance does allow a smaller gyro, at the expense of some zero-zero control loss (bladestrike?
).
Agree about designing in a system for dynamic stab aug though. A gyro could force helo to follow cyclic, giving linear displacement roll/pitch rate. The gyro could thus be embedded within the airframe (this is effectively how electromechanical SAS works).
Mart