The tube-and-wing aircraft configuration has remained unchanged since the start of commercial aviation. The state of minimum induced drag is comprised of an elliptically loaded wing, which has a constant downwash profile. Interrupting this wing with a central, payload-carrying body costs downwash, but is essential in fulfilling practical flight objectives. Initial drag and lift estimates, streamwise velocity profiles, as well as sectional and quasi-3D parasite drag estimates have been produced using force balance and ParticleImaging-Velocimetry (PIV) measurement techniques on a novel aircraft configuration, called the Gull-Wing Configuration. The results here indicate it is possible to restore an estimated 59% of the lost downwash while incurring no measurable increase in drag because of induced drag reductions, despite increases in parasite drag.
Nomenclaturefuselage diameter [cm] d' = distance from observation plane centerline to GW model centerline [cm] D = drag force [N] D' = drag force per unit span [N/m] Di = induced drag [N] e = Oswald efficiency factor k = induced drag factor l = body length [cm] lo = distance from wing chord-line to model body centerline [cm] L = lift force [N] L/D = lift to drag ratio q = dynamic pressure [Pa] Q = root mean square (RMS) of velocity fluctuations [m/s] Rec = chord-based Reynolds number S = wing planform area [ 2 m ] U = nominal mean freestream streamwise velocity [m/s] Uref = empirical mean streamwise velocity [m/s] (u,v,w) = streamwise, spanwise, and cross-stream velocity components [m/s] wi = induced velocity, or downwash, due to wing lift [m/s] (x,y,z) = streamwise, spanwise, and cross-stream coordinates [m] α = wing set angle [˚] = angle between model aft-body and model fore-body centerline [˚] t = time between laser pulses [μs] 2 ε = fractional increase in induced drag for non-elliptically loaded wing ν = kinematic viscosity [m 2 /s] = density of air [kg/m 3 ] θ = angle between freestream flow and model centerline [˚] Θ = momentum thickness [cm] Cd = sectional (2D) drag coefficient D
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