1. For the caseof atwo-dimensional inviscid flow in the x, z-plane, w'is reduced to G = qEy and the %owEquations (3- 5) can bewritten in the Cartesian coordinate system x, y, z of the non-inertial reference frame R in the following compact form:
2. lations (1415) are a parametric description of a :al. Note that Equation (14) includes a constant nponent along the direction ZW=. (s) and a harnit part. The constant vector multiplying cos(wt) Equation (14) is the orthogonal' complement of constant part, while the constant vector multiing sin(&) is orthogonal to the plane spanned by 0, &}. The magnitude of the vectors in the harnit part are, in fact, equal. Hencewe conclude that h spiral motions are the most general motion of aircraft for which a steady description is possible. a related discussion seethe classical book by von ES [14, pages 570 - 5711.