Compact lift systems of subsonic small-size unmanned aerial vehicles
Aerodynamics and heat-exchange processes in flying vehicles
State Engineering Design Bureau “Raduga” named after AY Bereznyak, 2а, Zhukovskogo str., Dubna, Moscow region, 141980, Russia
The paper presents the comparison of various types of aerodynamic characteristics of compact wing types using computer simulation. This problem was solved in three-dimensional statement given viscosity and compressibility. the author studied three types of grid wing; four types of contour wing, such as biplane cellule, which lifting surfaces were joined by vertical wing-tip pylons; and triplane cellule with vertical wing-tip pylons. The purpose of this research consists in checking appropriateness of using grid wings with planar airfoil as lifting and control surfaces for small-size subsonic unmanned aerial vehicles, compared with contour wings with convex airfoil. The sturies revealed that grid wings at subsonic speed have a great value of drag coefficient and very low value of lift-to-drag ratio. These parameters can be slightly improved by plane edges revision. The advantage of grid wings with planar airfoils is the ability to operate at very high angles of attack and a smooth nature of flow separation. Reducing the number of internal surfaces significantly reduces the drag coefficient, but lift coefficient reduces either (though not so much). We got in the limit the contour wing with planar airfoils of lift surfaces. It has rather high lift-to-drag ratio, but low lift coefficient. It may be increased by replacing planar airfoils by thick convex airfoils. Simulations have shown that at subsonic speed lift-to-drag ratio of the contour wing is higher than that of a grid wing by several times. Maximum lift coefficients of both types are approximately equal. This allows conclude that under the condition of solving problems of strength and rigidity, the contoured wing is more promising than the grid wing for most types of compact unmanned subsonic aircraft.
Keywords:aerodynamics, biplane, triplane, contour wing, grid wing, compact lift systems
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