Design and manufacturing of a thrust measurement system for a micro jet engine : Enabling in-flight drag estimation for subscale aircraft testing

Abstract: Good estimation of aerodynamic coefficients is of fundamental importance in the design and development process of an aircraft. Generally, these parameters are obtained using analytical, numerical and experimental methods, which are sometimes either inaccurate or very expensive. The use of subscale aircraft is becoming increasingly common in the study and evaluation of new aircraft concepts. Flight testing results in an efficient solution for obtaining parameters that can define drag characteristics. This project presents a solution for achieving the drag aerodynamic model from the design and manufacturing of a micro engine thrust measuring system integrated on subscale aircraft. Strain gauge technology permits to identify the stresses that the engine forces cause to the aircraft internal structure by analysing the strain of several strategic zones of the engine mounting created for this purpose. Different structural support geometries have been presented and stress-analysed together with the design of the appropriate strain gauge model conguration in order to select and manufacture a system that represents a good compromise between all the requirements while ensuring the quality and accuracy of the data acquired. After calibration, installation and set-up, the system is ready for real in-flight measurements.