Flight Test Applications of an Improved Operational Load Monitoring Device

This paper introduces a load monitoring device and its flight test applications for military aircraft. The device can digitize and record signals from optical fiber sensors and strain gauges. Some key flight parameters can be simultaneously recorded in the device, which is connected to an aircraft data bus cable. The device was installed on a low-speed aircraft and multiple sensors including fiber optic sensors and strain gauges were surface bonded on certain major structures. A total of 40 flight tests were conducted over 2 years. The recorded signals and parameters were successfully analyzed and reviewed to measure strains and vertical landing speeds and to estimate structural loads for over 200 flight hours. Structural load spectra were also obtained using the developed load monitoring device and compared with military specification and design spectra.