The Mach number, angle of attack and altitude of operation for an interceptor vary widely during the course of its trajectory. As a result, the interceptor Center of Pressure (CP) locations move significantly around a given Center of Gravity (CG) location at these operating conditions. This results in an inevitable variation in aerodynamic static stability leading to stable and unstable operating regions. In order to ensure good speed of response during the interceptor homing phase, lesser static stability is desirable. Hence the requirement to handle aerodynamic instability at some other operating conditions in the interceptor envelope become inevitable. Since flexibility has a strong bearing on autopilot design, it becomes necessary to control unstable operating points in the presence of flexibility modes. Despite the static stability variation, aerodynamic design can control the level of maximum instability of the configuration. Hence the maximum static instability the autopilot can handle has to be specified for aerodynamic configuration design. This paper brings out the limitations of autopilot design in controlling an unstable interceptor with low bending mode frequencies in terms of maximum instability the autopilot design can handle, which serves as an important input for aerodynamic design.

拦截器的马赫数、攻角和操作高度在其弹道过程中变化很大。结果，拦截器压力中心 (CP) 位置在这些操作条件下围绕给定的重心 (CG) 位置显着移动。这导致空气动力学静态稳定性的不可避免的变化，导致稳定和不稳定的运行区域。为了在拦截器归航阶段确保良好的响应速度，较低的静态稳定性是可取的。因此，在拦截器包线中处理一些其他操作条件下的空气动力学不稳定性的要求变得不可避免。由于灵活性对自动驾驶仪设计有很大影响，因此有必要在存在灵活性模式的情况下控制不稳定的操作点。尽管静态稳定性变化，空气动力学设计可以控制配置的最大不稳定性水平。因此，必须为空气动力学配置设计指定自动驾驶仪可以处理的最大静态不稳定性。本文提出了自动驾驶仪设计在控制具有低弯曲模式频率的不稳定拦截器时自动驾驶仪设计可以处理的最大不稳定性方面的局限性，这是空气动力学设计的重要输入。