A Nonlinear Correction Method on Elastic Lift Coefficient for Civil Aircraft

Abstract

Aerodynamic lift coefficient is nonlinear for an elastic aircraft flying at a high transonic speed, varying with Mach number and dynamic pressure. The common industry practice is that the correction on slope and intercept for linear segment of data curve of wind tunnel test, which is incapable of meeting increasing design requirements whereas aerodynamic coefficients are characterized by nonlinear nature. The nonlinear correction method for elastic lift coefficient is introduced by using equivalent angle of attack. Based on wind tunnel test data of rigid designed aircraft shape, elastic lift coefficient used for load and control analysis is directly obtained, which is applicable to different flight deformation state of a civil aircraft within the flight envelope. The wind tunnel test model was selected as a validation illustration. The analysis shows that the results obtained through the proposed correction method and the elastic test data are in a good agreement. The developed method takes into consideration both the computational efficiency and the precision.