Under these conditions, flapping, birdlike flight might well have some benefits over propeller-driven or helicopter flight.
在这种情况下，拍击，像鸟儿一样飞可能比螺旋桨推进飞行要好些。
2
The propeller can't work well.
螺旋桨工作不稳定。
3
It sets forth the computing method of rotor moment of inertia of the propeller and engine as well as the computing method of additional moment or angular velocity produced by precession.