Hybrid approach in the initial aerodynamic, stability and performance calculations of a light airplane

Abstract

The paper is focused on the preliminary aerodynamic analyses of a new light aircraft in symmetrical flight configurations. Initial calculations have been done using a 3D vortex lattice method. Since this method is based on inviscid flow concept, the non-linear calibration diagrams for the effectiveness and circulation of control surfaces have been derived from wind tunnel test data of an existing airplane. These calibration functions have been interpolated for a new light aircraft geometry, and analyses of lift and moment coefficients with different flaps and elevator deflections have been performed. Deflected flaps and elevator generate local lift redistributions which contribute to the induced drag, even at angles of attack when the total airplane lift is zero, which has been successfully determined by the applied CFD model. Parasite drag components, omitted by CFD calculations, have been obtained using DVL and Datcom methods and superimposed with CFD results, giving complete new aircraft polars, which have been successfully applied in longitudinal stability and basic performance estimates.