In-Flight Testing of MEMS Pressure Sensors for Flight Loads Determination

Abstract

The determination and monitoring of structural loads during flight is an important partof every certification program. It must be proved to the certification authorities that the loads occurring during specific flight maneuvers do not exceed the permissible component loads. Usually conventional strain gauges are used to determine structural loads, however an elaborate calibration process is necessary to determine these loads from the measuredstrains. Recent advances in sensor technology allow determining aerodynamic loads directly from pressure distributions measured by MEMS based sensors. When compared to strain gauges this measurement method has several advantages over conventional strain gauges interms of installation and calibration costs. Flight tests were carried out with the DLR researchglider aircraft Discus-2c in order to compare and investigate the loads determined with the two measuring methods. For this purpose a wing glove equipped with 64 MEMS pressure sensors on the airfoil surface was constructed. Different maneuvers with varying loads were performed during the test flights. A first evaluation of steady flight maneuvers shows that theloads determined from the measured pressure distribution are in very good accordance with the ones determined from the strain gauge measurements. This paper gives an overview of the flight test setup and the data analysis process, results from evaluations of trimmed wings-level flight and steady turn maneuvers are presented and discussed.