Real time contactless sensor for helicopter blade angle measurement

The present contribution concerns the activities carried out in the Clean Sky GRC5 MANOEUVRES project. The overall goal of the project is to provide an innovative system to monitor rotorcraft noise in flight, in view of performing optimized low-noise terminal procedures. To achieve this goal it is necessary to estimate in real time the main rotor tip-path plane (TPP) orientation with respect to the vehicle airspeed vector, which in turn depends on the TPP orientation with respect to the helicopter airframe. An in-flight contactless measuring system, capable of measuring the three angles of a helicopter blade with respect to the hub, is proposed and validated. Its development is detailed, starting from the selection of candidate technologies up to the final demonstration of a prototypal device on board an AgustaWestland AW139 prototype helicopter.