Spanwise distribution of induced drag in subsonic flow by the vortexlattice method

Abstract

Nomenclature A = aspect ratio Cot = total induced drag coefficient of surface CDW = total induced drag coefficient given by Vortex Lattice Method CD^ = total induced drag given by wake integral CL = total lift coefficient of surface c = chord length of strip c = average chord length of surface Cdi = induced drag coefficient of strip ci = lift coefficient of strip Dd = normalwash factor at bound vortex DC -normalwash factor at control point d = induced drag coefficient of box e = semiwidth of strip M = Mach number p = pressure coefficient of box S = reference area s = semispan of surface Wb = dimensionless normalwash at bound vortex w c = dimensionless normalwash at control point x,y,z = Cartesian coordinates a.= angle of attack ai = induced incidence at bound vortex 77 = dummy spanwise coordinate

Invariant Formulation for the Minimum Induced Drag Conditions of Nonplanar Wing Systems

“…A computationally efficient option is represented by panel codes. [16][17][18][19][20] In the preliminary design it is also beneficial, due to the requirements of inexpensive computational methods, to evaluate the induced drag with even faster tools based on lifting line models such as the ones of References [9,21,22]. The optimal condition, when only constraints of total lift and wingspan are considered, is represented by the well known elliptical solution.…”

Sizing of High Aspect Ratio Wings with Folding Wing Tips

“…Figure 20 shows the calculated drag polar of the aircraft models with various wing aspect ratios. The induced drag was computed by summing up the drag over all chordwise strips on the wing surfaces, determined based on the spanwise lift distribution [42] and the zero-lift drag was calculated empirically by adding up all contributions from individual component including the wings, fuselage and nacelle using the formulation given by Raymer [43].…”

Aeroelastic Analysis of T-Tails Using an Enhanced Doublet Lattice Method

“…The third term includes the unsteady induced drag and the unsteady lift and drag due to the motion of the doublet line. This way of calculating induced drag is not physically correct but fortuitously provides a useful estimate [10][11][12].…”