Angels 60, i think you're getting alittle bit confused. A rolling tendancy will occur due to retreating blade stall, which will be one of the criteria taken into consideration when determining a helicopters VNE. Retreating blade stall will occur as the speed of the helicopter increases to the point at which the flapping down of the retreating blade has increased the angle of attack of the retreating blade to it's stalling angle. As soon as any airflow occurs over the rotor disc there will be a difference in the airspeed between the advancing and retreating blades. This will lead to dissymetry of lift, which will be partially compensated for by blade flappping. This will allow safe flight within the flight manual speed parameters. The pilot may have to sit in a specified seat due to C of G considerations, but he certainly won't be required to compensate for a rolling tendancy due to aerodynamic instability in the cruise! If he has to do that, i suggest he find a different helicopter to fly - ie one that has been certified!!
