LIFTING-LINE theory [1,2] is the foundation for much of our understanding of finite-wing aerodynamics. Solutions based on lifting-line theory are widely accepted and have been shown to be in good agreement with CFD [3-10]. From Prandtl’s analytic solution to the classical lifting-line equation [1,2], the wing section-lift distribution can be expressed as a Fourier series of the form [11]
*bL*^{~} (θ)/L = (4/π)[sin(θ) + Σ^{∞}_{n-2} B_{n}sin(nθ)]; θ = cos^{-1}(-2z/b) (1)

where *b* is the wingspan, *L*^{~} is the local wing section lift, *L* is the total wing lift, *z* is the spanwise coordinate, and *B*_{n} are the Fourier coefficients. For any given planform, the twist distribution required to produce this lift distribution can also be obtained using Prandtl’s lifting-line equation [12]. In steady level flight, *L* is equal to the weight, *W*, and the induced drag can be written as [11]

*D*_{i} = (2(W/b)^{2}/πρV_{∞}^{2})[1+ Σ^{∞}_{n-2} B_{n}^{2}] (2)

where *ρ* is the air density and *V*_{∞} is the freestream airspeed.

]]>