This paper proposes novel wing planforms that reduce induced drag by exploiting the slipstream in aircraft driven by propellers in tractor configuration. The novel planforms are determined by optimization through an extended lifting-line theory that accounts for slipstream effects and an optimizer that includes the option of using an appropriate number of Bézier polynomial weights as control parameters describing wing planform. The optimization package written for the purpose (PROWING) minimizes a user-selected cost function, subject to a wide class of geometric and mechanical constraints on such variables as root chord, tip chord, span, wing area, bounds on wing twist and chord, airfoil profiles, root bending moment, etc. A general feature of the optimal wing planforms so generated is that the chords are shorter within the slipstream and longer on either side of it. For a wing of aspect ratio 12 and prescribed wing area, PROWING predicts that an optimal planform can reduce induced drag by about 9.15%, with a maximum local wing chord variation of about 37% over a conventional reference wing. PROWING-based optimal planforms have been assessed in two ways: 1) by an Euler code that includes a blade-element theory module for the propeller and accounts for the aerodynamic effect of the propeller slipstream on wing planform; and 2) by a Reynolds-averaged Navier–Stokes simulation coupled to the blade-element theory module. Both assessments confirm that the class of planforms proposed here reduce drag but with slight differences, which is not unexpected because of the different assumptions underlying the different methods.
Optimal Low-Drag Wing Planforms for Tractor-Configuration Propeller-Driven Aircraft
Journal of Aircraft ; 52 , 6 ; 1791-1801
2015-11-01
Article (Journal)
Electronic Resource
English
Optimal Low-Drag Wing Planforms for Tractor-Configuration Propeller-Driven Aircraft
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