Innovative Rotor-state Measurements Enabling Helicopter In-flight Noise Monitoring and Enhanced Attitude Control

We give a comprehensive illustration of a new approach to rotorcraft noise abatement carried out in the framework of the Clean Sky collaborative project MANOEUVRES. This approach is based on technologies and tools for real-time, in-flight monitoring of the emitted noise. By means of a new cockpit instrumentation, the Pilot Acoustic Indicator (PAI), the current noise impact is presented to the pilot in a condensed, practical form as an aid in performing quieter maneuvers. The PAI algorithm makes use of several ingredients that have been implemented and tested within the project, including offline steady and unsteady acoustic predictions, and estimation of flight mechanics parameters based on the measurements derived from a new contactless rotor state measurement system. The latter is capable to accurately acquire the motion of the rotor blades, allowing the computation of non-directly-measurable quantities such as tip-path-plane angle of attack and thrust coefficient, and offering a reliable support for the development of enhanced attitude control laws based on the Rotor State Feedback approach. The paper reports on the current state of the project, which is close to its completion.