Structural health and usage monitoring of an unmanned turbojet target drone

Aerial target drones are an important tool for the training of anti-air batteries and missiles for defense and homeland protection. These target drones are highly loaded structures that require a reliable inspection after each flight. A health and usage monitoring system based on load path changes has been developed. These changes are measured with fiber optic Bragg grating sensors which have been implemented in high loaded structural parts of the fuselage of the DIANA I-A, which is operated by the Spanish National Institute for Aerospace Technology. The health and usage monitoring system has been tested and calibrated by destructive tests, introducing defined damages in fuselage stringers and evaluating the structural damage by the measured strain distribution. The tests have shown that a simple system based on four fiber optic Bragg grating sensors is able to detect barely visible structural damages in the entire high loaded front fuselage of the drone. The health and usage monitoring system requires only on-ground equipment and enables a fast turnaround of the drone after each flight. Two DIANAs have been instrumented for their application in service. First flight tests have been performed and the performance of the health and usage monitoring system has been evaluated.