1319. A Technique for Balancing Missile 2-Axis Gimbaled Antenna Systems

Paper

Abstract

With the advent of electrically driven missile gimbal antenna systems, mass balancing has become a critical requirement. Unlike their former hydraulic powered counterparts, electrically driven gimbals generally have limited amounts of power available, due to weight and packaging consideration. Therefore, it is mandatory that the center of gravity location of the gimbaled parts coincide with the motor axis of rotation (within limits) in order to conserve power. This paper presents a technique for quickly and accurately balancing 2-axis gimbaled antenna systems, after final assembly, and in the fully cabled condition. The method chosen utilizes a cylindrical gas bearing center-of-gravity instrument with a precision horizontal rotary table for mounting the test article. The cg instrument is coupled to an automatic data recording and reduction system which provides a paper tape of test results. In a production set-up, the tape becomes part of the Quality Assurance records. The data reduction system incorporates a computer program for determining unbalance about each axis. A separate program determines the optimum adjustments which should be made to the balance trim screws, which are designed into the gimbal system. A unique feature of the technique has to do with the positioning of the test article in the fixture such that all information needed for balancing can be obtained in one set-up (i. e., without rotating the unit 90 degrees to measure another axis). A discussion of the software, rationale for fixturing, environmental requirements for test areas, along with sensitivity and accuracy results, follows.