Linear Equations of Longitudinal Dynamics

Here, the linearized versions of the equations of longitudinal motion will be deduced, corresponding to what is known as the quartic and the quintic descriptions of the dynamics of wing-in-ground-effect vehicles. In other words, linearized equations of motion and corresponding characteristic equations
are written with and without accounting for perturbation of the forward speed. Instead of the representative kinematic parameters a (angle of attack) and h (relative ground clearance) utilized by Kumar and Staufenbiel, the parameters в (pitch angle) and h (relative ground clearance) will be employed. In what follows, all unsteady aerodynamic derivatives will be incorporated.

The pair of parameters 6,h is more practical in the aerodynamics of ground-effect vehicles than a, h. The use of #, h was first proposed by Treshkov [180] and since has been adopted in most of the Russian devel­opments on wing-in-ground-effect vehicles.