Aerodynamic Influence Coefficients from Strip Theory

T N ANY AEROELASTIC ANALYSIS by collocation methods, both structural and aerodynamic influence coefficients must be known. We consider here the derivation of the aerodynamic influence coefficients (AICs) from the simplest of the aerodynamic theories—that of strip theory in which the flow along any section of the wing can be considered as two-dimensional. The type of AICs necessary in an aeroelastic analysis must relate the controlpoint forces, F (rather than pressures) to the deflections, h, or streamwise slopes. In the present treatment, we prefer the deflections rather than streamwise slopes as the generalized coordinates because the deflections have a more general meaning on a cambered surface and deflection influence coefficients are more readily obtained from a structural analysis than slope influence coefficients. Accordingly, we define a steady matrix of AICs, [CHS], by