Assessment of Control Allocation Optimization on Performance and Dynamic Response Enhancement of a Compound Rotorcraft

Open Access
Author:
Thorsen, Adam Thomas
Graduate Program:
Aerospace Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 20, 2014
Committee Members:
  • Joseph Francis Horn, Thesis Advisor
Keywords:
  • compound
  • rotorcraft
  • performance
  • dynamic response
Abstract:
This research investigates control allocation for a compound rotorcraft to minimize power required in acceleration, pull-up, and turning maneuvers and examines the transient response characteristics of a compound rotorcraft in order to establish methods of control that enhance handling qualities via the use of redundant control surfaces. Simulations of a hypothetical compound rotorcraft based on an H-60 airframe and rotor compounded with a wing and pusher propeller are used. Background is provided on the simulated compound rotorcraft’s performance in trim and the trim methodology employed, the simulated compound rotorcraft model, and the behavior of redundant controls in minimum power quasi-steady maneuvering flight; then the focus shifts to the transient response characteristics of the aircraft in various maneuvers. In addition to the four traditional controls, this research will examine the use of five redundant control effectors: rotor speed, propeller pitch, symmetric stabilator deflection, symmetric wing flap deflection, and differential wing flap deflection, which can be optimized for performance in trim and maneuvering flight along with handling qualities. The results of the minimum power quasi-steady maneuver optimization are incorporated into a g-command dynamic inversion controller that regulates longitudinal and vertical load factor in minimum power flight. This g-command controller is used to achieve optimal control allocation with regards to the propulsive force distribution between the main rotor and propeller, and the lift force distribution between the main rotor and wing. Pull-up and turning maneuvers are simulated to analyze predicted handling qualities both with and without redundant controls. Quickness metrics (agility, roll attitude, and turn quickness) are also 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.