Evaluating the Impact of Parasitic Drag on the Accuracy of Endurance Predictions

Abstract

The cost-effectiveness and versatility of electric unmanned aerial vehicles (UAVs) has led to an increase in demand for efficient payload-carrying aircraft [4]. Many project criteria require an endurance prediction based on a specific mission profile. Current methods for determining the endurance of fixed-wing UAVs involves estimating the key variable of parasitic drag using empirical equations and approximated drag values. This study seeks to evaluate the impact of estimating parasitic drag using conventional methods on the accuracy of endurance predictions for UAVs. Using glide tests, drag is measured for a small electric aircraft, and compared to predictions made using the component drag build up-method for conventional aircraft. It is demonstrated that the parasitic drag generated by small UAVs is sufficiently large to invalidate endurance predictions based on coefficients of drag calculated with the standard component drag build up method developed for fixed wing aircraft.