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为研究自转旋翼机的纵向稳定性,首先应用配平分析法求出各个飞行状态的旋翼转速,求出转速后用列文伯格-马夸尔特算法对旋翼机的姿态和操纵进行配平,得到各个飞行状态的姿态角和操纵量。运用五点中心差分法求纵向稳定导数,从而得到状态矩阵以及纵向运动模态,然后建立旋翼机纵向稳定性分析模型,利用所求得的一些模态分析旋翼机的稳定性。研究结果表明,旋翼转速随前飞速度的变化不明显,旋翼机的操纵主要是纵向的,旋翼转速主要取决于桨盘的倒角;在速度范围内,除了旋翼转速模态,旋翼机的其他纵向模态是稳定的,旋翼自由度与旋翼机机体存在耦合,重心相对推力线的垂直位置对稳定性有明显的影响,重心位于推力线上方具有更好的稳定性。
In order to study the longitudinal stability of rotorcraft, the rotational speed of rotorcraft at each flight state was calculated by the method of balance analysis. After the rotation speed was calculated, the attitude and maneuvering of rotorcraft was trimmed by Levon-Marquardt algorithm. Attitude and manipulation of each flight state. The five-point center difference method is used to find the longitudinal stability derivative, and the state matrix and the longitudinal motion modal are obtained. Then, the longitudinal stability analysis model of the rotorcraft is established, and the stability of the rotorcraft is analyzed by using some obtained modalities. The results show that the rotor speed changes little with the former flying speed, the operation of the rotorcraft is mainly vertical, and the rotor speed mainly depends on the chamfer of the paddle. In the speed range, except the rotor speed mode, the other Longitudinal mode is stable. Rotor freedom is coupled with rotor body. The vertical position of center of gravity relative to thrust line has obvious influence on stability. The center of gravity is located above thrust line and has better stability.