Use of Redundant Controls to Enhance Transient Response and Handling Qualities of a Compound Rotorcraft

This study investigates the transient response characteristics of a compound rotorcraft and seeks to establish methods of control that enhance handling qualities via the use of redundant control surfaces. Simulations of a hypothetical compound rotorcraft based on a UH-60A airframe and rotor compounded with a wing and pusher propeller are used. This study presents general background on the simulated compound rotorcraft model, the behavior of redundant controls in minimum power quasi-steady maneuvering flight, and then extends the analysis to focus on the transient response characteristics of the aircraft in various maneuvers. In addition to the four traditional controls, this study will examine the use of three redundant control effectors: propeller pitch, symmetric wing flap deflection, and differential wing flap deflection, which can be optimized for performance and handling qualities. Background material is presented for trim analysis of quasi-steady maneuvers to gain an understanding of the control allocation that minimizes power required in sustained maneuvers. The results of the optimization are incorporated into a g-command dynamic inversion controller to regulate longitudinal and vertical load factor in minimum power flight. Pull-up and turning maneuvers are simulated to analyze handling qualities both with and without redundant controls. Quickness metrics are investigated for pull-up and turning maneuvers to understand how the deployment of redundant controls might be used to enhance transient response and handling qualities.