helicoptern.直升飞机vt.用直升飞机载送vi.乘直升机helicopter training直升机训练helicopter dynamics直升机动力学helicopter aviation直升机航空兵,直升机部队helicopter hovering直升机悬停helicopter structure直升机结构helicopter stability直升机稳定性helicopter acoustics直升飞机声学helicopter autopilot直升飞机自动驾驶仪helicopter air combat直升机空战Helicopter Blade Slap直升机桨叶松动(声)