An Implementation of the Vortex Lattice and the Doublet Lattice Method

Abstract

This report documents the implementation of a Vortex Lattice Method (VLM) and a Doublet Lattice Method (DLM) in Python. The aerodynamic influence matrices (AICs) obtained from this implementation are validated with respect to MSC.Nastran for both the parabolic and the quartic integration schemes of the DLM. The test cases include dihedral and sweep of the main wing, wing-empennage configurations with the horizontal tail planar to the main wing, near-planar and further away (e.g. T-tail) and with/without a vertical tail. The test cases have been inspected at different mach numbers and reduced frequencies. For all tested aircraft configurations the results were found to be equivalent to MSC.Nastran in a numerical sense. Using panels which are misaligned in y-direction provokes differences and errors.