Further Convergence Studies of the Enhanced Doublet-Lattice Method

Abstract

The doublet-lattice method (DLM) has become a standard source for the aerodynamic loads in  utter and dynamic response analyses of aircraft at subsonic speeds. A recent reŽ nement to the method is based on an improvement to the integration of the oscillatory kernel function by replacing the parabolic approximation in the kernel numeratorwith amore accurate quartic approximation.This reŽ nement extends the frequency limits of the DLM for applications to higher-frequency  utter and dynamic response. The effects of Mach number and lattice geometry on convergence by numerical experimentationwith some previously studied conŽ gurations are reviewed as well as a realistic aircraft model, present guidelines are reviewed, and updated guidelines for box aspect ratio and number of boxes per wavelength are presented.