Selected issues of designing and testing of a HALE-class unmanned aircraft

Abstract

This work presents the research connected with designing an unmanned aerial vehicle with long mission endurance. Specification of HALE aircraft as well as the possible operating scenario of HAPS system is presented. Issues connected with operating the aerial vehicle at stratospheric altitude are discussed. A mission profile itself is also presented. A construction project of the aerial vehicle and its possible equipment is suggested. Regarding the fact that the aircraft is to perform high-altitude flights, it faces airfoil operation at very low Reynolds numbers. That is why, research concerning quality operation airfoil of low drag airfoil at a stratospheric altitude was carried out. For this reason, the influence of flights at subcritical Reynolds numbers on aerodynamic characteristics is presented. A series of simulation studies and model-based research in a hydrodynamic tunnel were carried out. It follows from the conducted numerical analysis that the decrease in aerodynamic excellence of the airfoil operating at 15 km altitude is small in relation to the airfoil operating at the height of 0 m. The research carried out in the aerodynamic tunnel confirms the efficiency of the airfoil operation at low Reynolds numbers. The work will be continued in order to check the influence of a turbulator on the shift of the range of Reynolds number, and consequently on the improvement of the aerodynamic quality of the airfoil.