Rotating camera system for in-flight propeller blade deformation measurements

Abstract

The behaviour of the blades of a propeller or rotor during operation is crucial for its performance and operational saftey. Particularly the bending and twisting of the blades under load are of high interesst, because they directly influence the local angle of attack and thus the performance of the propeller. Up to now only local deformation measurements by means of strain gauges or acclerometers were feasible. The required cabling thereby limits the maximum number of sensors and thus avoids areal measurements. Furthermore, the application of the sensors can influence the mechanical and aerodynamic properties of the blade. A direct shape or location measurement is also not possible with those techniques. The presented measurement method IPCT (“Image Pattern Correlation Technique”) in addition with the application of the newly developed rotating camera system now enables the non-intrusive measurement of the shape and location of propeller- and rotor blades in-flight with a high accuracy. In the beginning of the paper, the measurement technique and the rotating camera are outlined. Later, the performed ground tests and the conducted flight test activities are described briefly and first measurement results are shown. The major part of the development of the rotating camera was funded by the European Commission within the FP7 project AIM2 (contract no. 266107).