Hi,
While not completely new here, I had to re-register because -obviously- old lockon.ru logins wont't work.
I bought BS about 20 days ago and I must say I am highly impressed with the flight modeling.
That said, most people here seem to think in terms of fixed wing aircraft which were featured in lockon.
So let us get some things straight:
Most of you are familiar with the term "Angle of Attack (AoA)" of an airfoil. You know what it does, you flew lockon and maybe countless other sims.
As you are aware, the greater the angle of attack, the more lift a rotor blade (practically a wing) generates and more power is required to drive it through the air at a given speed, because of drag. All your controls work by changing the pitch angle of the rotor blades.
If the rotor was operating in motionless air, pitch you command with the cyclic and AoA would be the same in value. But, this is only true when the rotor spools up. Once the rotor is spinning, it creates a constant downwash through the rotor "dish".
If there's an air current through your rotor disc, as when hovering or moving over the ground, this also changes the effective AoA of the rotor blades.
The half of the rotor disk that is moving forward into the wind, has a higher AoA and higher airspeed than the retreating half. This means, if you picture it from above, that the rotor generates more lift on the advancing than on the retreating side.
So, your aircraft has the tendency to roll to the side that is generating less lift.
Enjoy flying a helo for what it is :)