Generic Approach to Determine Optimum Aeroelastic Characteristics for Composite Forward-Swept-Wing Aircraft

Aeroelastic tailoring, a concept which is critical to the development of forward-swept -wing aircraft, is presented as a multivariable optimization problem in which all of the variables have to be considered—a departure from the current practice in which the fiber orientation angle seems to be the only variable used in the tailoring process. A transformation of the aeroelastic equations of motion for a composite swept wing reveals that the critical aeroelastic characteristics for flutter and divergence are expressible in terms of three bounded generic stiffness variables and the fiber orientation angle. A variation of these variables within their various limits permits a view of the complete continuum of the critical aeroelastic parameters for all composite materials. The results for aeroelastic divergence presented in this paper show that 1) divergence can be eliminated for a) any forward-swept angle and b) a forward-swept wing whose fiber orientation angles are swept back relative to the spanwise reference axis; and 2) an optimum aeroelastically tailored forward-swept wing is one that uses different composite materials oriented at various angles (a configuration that also enhances the wing's strength).