Improving Handling Qualities by Handling the Air Resonance Mode

Abstract

The paper presents an active controller to increase stability of the air resonance mode of DLR's Flying Helicopter Simulator, FHS, research helicopter. The air resonance mode on the FHS is particularly excited when roll rate feedback loops are incorporated in the main flight control system design. First models derived from system identification are adapted and tuned for reproducing the air resonance mode as identified in flight tests. These models are used as simulation environment to optimize the controller. The air resonance controller was flight tested to proof its air resonance cancelling effect and to study the influence on the flight control performance and handling qualities. The final air resonance controller is designed to operate independent of the main flight control system.