TOPICS ON FLEXIBLE AIRPLANE DYNAMICS Part Ⅱ. The Application of Flexible Airframe Transfer Function Approximations and the Sensitivity of Airframe Transfer Functions to Elastic Mode Shapes

摘要

The generality of the airframe transfer function factor approximation formulas presented in ASD-TDR-279 is tested by applying them to three different aircraft. The equations of motion for the test cases are presented and the exact and approximate factors have been tabulated.nThe approximation formulas are then utilized to calculate the sensitivity of the flexible airframe transfer function factors to mode shape. The formulas are given in terms of airplane stability derivatives which in turn are functions of the elastic mode deflections. Then, using the results of ASD-TDR-62-279, the desired sensitivity is readily calcu¬lable. Many of the transfer function factors are shown to be relatively insensitive to mode shape, thus allowing effective approximation. A review of the literature pertaining to approximate methods for calculating elastic mode shapes is presented in the form of an annotated bibliography.