Development and Testing of Innovative Solutions for Helicopter In-Flight Noise Monitoring and Enhanced Control Based on Rotor State Measurements

The problem of the on-board monitoring of rotorcraft acoustic impact has been studied in an original way, through the development of an integrated system concept in which the pilot is offered an estimation of emitted noise by means of a new cockpit instrument, the Pilot Acoustic Indicator. The noise estimation is obtained in real time by exploiting several parameters retrieved from the aircraft avionics, essentially augmented by offline acoustic predictions and current main rotor blade motion information. As such, this innovative methodology heavily relies on the availability of a new rotor state measurement system capable to acquire the blade dynamics in an accurate and fast way. Such a system may effectively support additional applications, such as Rotor State Feedback control strategies, aimed to enhance fundamental aircraft handling qualities, leading to improved pilot/vehicle capabilities. The complex system concept is illustrated with its main components, updating previous descriptions and reporting on the final phases of this activity. This involved the correlation of acoustic predictions with experimental flight data, the final demonstration of the Pilot Acoustic Indicator through piloted simulation, and the final flight testing of the new rotor state measurement system on board an instrumented helicopter.