Coursework
Winglet Analysis for a Long-Endurance Cargo UAV
Using Whitcomb span equivalence to turn a non-planar geometry problem into a planar parametric sweep, avoiding near-singular influence matrices in vortex-lattice analysis.
How winglets affect the cruise aerodynamic performance of a 3500 kg, 19 m span long-endurance aircraft.
Modelling a winglet as a separate non-planar surface produces a near-singular influence matrix at the junction, which is numerically awkward at low fidelity. This study instead adopts the Whitcomb principle: a winglet reduces induced drag primarily by extending the wing’s effective span, so a planar wing of higher aspect ratio is a clean upper bound on the benefit any winglet of comparable height could deliver.
Using OpenAeroStruct with OpenMDAO, induced drag was minimised with SLSQP under a trimmed lift coefficient constraint, sweeping aspect ratio (12–21), taper ratio (0.3–1.0) and twist (−5° to +3°). Mesh doubling changed the result by less than 0.5 counts.
Result: a 1.5 m equivalent winglet improves L/D by up to 15%, while planform optimisation alone already yields about 5.7%. That suggests a clear design priority — get the planform right before adding structure.