TANDEM-SCHEME UAV LIFT-DRAG RATIO INCREASING WITH HELP OF AIRFOILS CHOOSING

Abstract

In the last decade folding tube launch UAV became common, for which aerodynamic scheme tandem is reasonable. By the time tandem-wing aerodynamic characteristics are researched much less than ones of traditional scheme.In present work comparison of different UAV geometries lift-drag ratio and longitudinal stability was performed with help of analytic and CFD methods. Geometries with negative and zero differences of forward and rear wings inclination angles were considered (in last case with stall-strips on forward wing and with different airfoils of forward and rear wing).It was shown that for negative difference of inclination angles tandem-scheme can be exploited for wide range of centering and can be optimized for cruise flight (without balancing loss) while stability maintenance at high angle of attack.For zero difference of inclination angles UAV with stall-strips or with different airfoils of forward and rear wing also can be longitudinally stable in wide range of angle of attack, but is attributed by significant balancing losses. For eliminating of this effect airfoils with positive can be used, but they have lower maximal lift-drag ratio.