傳統科學認為 ， 你要飛 起碼要四塊固定螺旋槳 因為要控制四範嘢 ︰ 滾轉 、 俯仰 、 偏航同加速
Conventional science says that if you want to fly, you need at least four fixed propellers because you have to control four things: roll, pitch, yaw and acceleration