Comparative Dynamic Analysis Of Tiltrotor Drive Train Configurations Using The Transfer Matrix Method

Abstract

This paper presents a general torsional modeling and analysis approach based on the Transfer Matrix Method applicable to tiltrotor drive train configurations. A novel transfer matrix model for the rotating blade's lead-lag mode is derived and integrated to establish coupled rotor-drivetrain-engine dynamic models. Based on XV-15 tiltrotor, three distinct drive train configurations are developed. The modal results of representative configuration obtained by the proposed method are validated against flight test data and the Finite Element Method, demonstrating a close agreement for both helicopter and airplane modes. The dynamic analysis reveals that the transition between flight modes has negligible impact on the torsional mode of the drive train system. Furthermore, minor architectural differences, such as the tilting mechanism, do not significantly alter the dynamic characteristics. However, a major change in engine layout, from a dual-engine, side-by-side arrangement to a single, centered engine, results in a markable shift in the natural frequency of the system.