A 3D imaging system for the non-intrusive in-flight measurement of the deformation of an aircraft propeller and a helicopter rotor

Abstract

The non-intrusive in-flight measurement of the deformation and the resulting local pitch of an aircraft propeller or helicopter rotor blade is a demanding task. The idea of an imaging system integrated and rotating with the aircraft propeller has already been presented at the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been designed, constructed and tested in the laboratory as well as in-flight on the Cobra VUT100 of Evektor Aerotechnik, Kunovice (CZ). The major aim of the EU FP7 project AIM² (”Advanced In-flight Measurement techniques 2” – contract No. 266107) was to ascertain the feasibility of this technique under extreme conditions - vibration and large centrifugal forces – to real flight testing. Based on the gained experience a new rotating system for the application on helicopter rotors has recently been constructed and tested on the whirl tower of Airbus Helicopters, Donauwörth (D). In this paper the principle of the applied Image Pattern Correlation Technique (IPCT), a specialized type of Digital Image Correlation (DIC), is outlined and the construction of both rotating 3D image acquisition systems dedicated to the in-flight deformation measurement of the aircraft propeller and helicopter rotor are described. Furthermore, the results of the ground and in-flight tests of these systems will be shown and discussed. The obtained results will be helpful for manufacturers in the design of their future aircrafts.