Drag Balance Instrument

The drag balance instrument, which is an integral part of the satellite, consists of an inner mass, an elastic element, and an outer shell. The drag balance is the connecting elastic element between the outer light shell and the inner heavy body. The center of the balance is located at the satellite's geometric center, or that point which is the geometric center both of the inner body and the shell. This instrument measures the relative translations between the shell and the inner body both in value and direction, resolving any relative translation along three mutually orthogonal axes. These three axes are fixed to the body, one of them being coincident with the polar symmetry axis of the satellite. Being fixed to the satellite, the axis rotates with it in the free-precession motion around the center of gravity. The balance is designed in such a way that the maximum translation between the shell and the drum is generally of the order of 0.01 mm. In most cases the drag force at the apogee is negligible, and therefore the apogee data are used to get an inflight calibration of the balance. The translation of the elastic system is changed into voltages that are amplified and demodulated to obtain dc signals.

该拖曳平衡仪器，作为卫星的不可或缺组成部分，由内质量、弹性元件和外壳构成。拖曳平衡作为连接外轻壳与内重体的弹性连接元件。平衡中心位于卫星的几何中心，亦即内体与外壳的共同几何中心。该仪器能够测量外壳与内体之间的相对位移，包括其数值与方向，并沿三个相互垂直的轴线解析任何相对位移。这三个轴线固定于本体上，其中之一与卫星的极对称轴线相重合。由于固定于卫星上，该轴线随着卫星在质心周围的自由进动运动而旋转。该平衡仪器的设计使得外壳与鼓之间的最大位移通常为0.01毫米量级。在大多数情况下，远地点的阻力力可以忽略不计，因此使用远地点数据来对平衡仪进行飞行校准。弹性系统的位移被转换为电压，经过放大和解调以获得直流信号。