A method proposed by Skelton (ref. 13.11) for a study of a VTOL airplane is in some respects similar to both the preceding and following methods, yet different from each. In it three points on the vehicle, for example two wing tips and the tail, are used to identify nine inputs—three gust components at each of these three control points, thus
that the disturbance velocity field is linear in both x and y, so that a change in wgi for example implies a change in wg over the whole vehicle of an amount proportional to the perpendicular distance from the line passing through points 2 and 3. In making an assumption about the whole velocity field associated with each input it resembles the following method. The complete gust matrix T in this formulation of the analysis, for six degrees of freedom would be a (6 X 9) matrix. However it would with the usual assumptions separate into two smaller matrices for lateral and longitudinal subsystems.

For further details the reader is referred to ref. 13.11.