Trailing-edge flap optimization for lift distribution control

This paper outlines an algorithm for determining the optimal spatial distribution for a set of trailing-edge flaps on an aircraft wing with the goal of achieving a specified lift distribution for enhanced performance. The wing's naturally occurring aerodynamic influence functions are used in a finite Fourier series expansion, and coupled with an optimization algorithm, to determine the flap spatial distribution and deflections required to achieve minimal integrated mean-squared-error between the desired and the resulting wing lift distributions. The influence functions are non-orthogonal and a method from image processing is adapted and implemented in this problem to account for the non-orthogonality by applying a correction to the Fourier coefficients of the desired shape expansion. An extension of the algorithm is presented that allows for the determination of the optimal flap spatial distribution for a set of desired or specified lift distributions simultaneously, based on the relative weighting of each lift distribution. An example is given that shows the resulting optimal flap spatial distributions for a set of 4-16 trailing-edge flaps on a conventional model aircraft, with the goal of reproducing an elliptical lift distribution. Construction and flight testing of a model aircraft with an optimal set of trailing-edge flaps and span-wise pressure sensors is in progress. Copyright 2008 by Nelson M. Guerreiro and James E. Hubbard, Jr.

Trailing-edge flap optimization for lift distribution control Conference Paper