That is because the blades, being behind the pole and at an Angle to it, can be given more freedom to yaw about than they would have in an upwind turbine.
那是因为叶片轮处于极轴的后方并以一定的角度倾斜，这样比逆风涡轮机有更大的自由度来偏离原来的位置。
2
The mathematic model has four degrees of freedom (surge, sway. yaw and roll), taking the couple motion of roll on horizontal plane motion into account.