Aerodynamic hysteresis at high sideslip for unconventional fixed-wing UAV
Katarzyna KaniaPurpose
The purpose of this paper is to numerically investigate the aerodynamic hysteresis with respect to sideslip for an unconventional (double-delta flying wing) UAV. The impact of transient effects on aerodynamic characteristics in yawing motion is investigated, including the rate with which the aircraft rotates. The aircraft considered in this study is characterized by strong aerodynamic coupling resulting from the vortex flow.
Design/methodology/approach
The study focuses on a quantitative approach, using numerical analysis based on the results from the Ansys Fluent software. The change of aerodynamic coefficients with sideslip is considered for two angles of attack for unsteady and steady approaches. The research refers to dynamic conditions.
Findings
The results reveal that for the considered unconventional double-delta configuration the impact of hysteresis cannot be neglected only for the rolling moment, because accounting for unsteady effects leads to different changes in the lateral static stability with sideslip. It was also found that the relation between the impact of yaw rate on the rolling moment does not change linearly with the value of the yaw rate. The effects for two angles of attack are similar, but not identical, with hysteresis’ impact being more severe for a lower angle of attack due to weaker vortices which are more prone to breakdown. For low sideslip, the hysteresis effect can be neglected altogether.
Originality/value
This research offers a novel perspective on how transient effects affect the aerodynamic characteristics – mostly the lateral stability – for unconventional aircraft for a wide range of sideslip angles. The study’s findings contribute to the development of unconventional aircraft, for which it is hard to establish which simplifications in the mathematical model are acceptable. This investigation also hints as for how the derivatives with respect to the yaw rate should be calculated.