Rotating WT rotors will tend to align themselves to face the oncoming wind (even upwind rotors will do this). A WT which allows this natural tendency to align the rotor is known as a free yaw WT. This mode of operation is not popular in large WTs due to the possibility of damage from gyroscopic forces. Also, rotors will not recover from positions of large yaw misalignment, for example after periods of calm or sudden large changes in wind direction.