NASA Reference Publication 1207 (RP-1207, 1988) is the go-to handbook for turning a detailed aircraft simulation into a compact set of constant matrices that control-systems engineers can design around. Critics seize on one introductory sentence that speaks of a “flat, non-rotating earth,” but that phrase is nothing more than a standard short-range approximation. In practice, RP-1207 has powered research from the F-15 ACTIVE programme to NASA’s Generic Transport Model.
“A linear aircraft model for a rigid aircraft of constant mass flying over a flat, nonrotating earth is derived and defined.”
Engineers adopt this wording because, over the short distances and time scales relevant to flight-dynamics work, Earth’s curvature and the Coriolis acceleration (≈ 0.01 g at jet speeds) are tiny compared with aerodynamic forces. Bernard Etkin’s classic Dynamics of Atmospheric Flight—a standard university text—uses the very same “flat, non-rotating” assumption, underscoring that RP-1207 is following textbook practice rather than revealing hidden knowledge about Earth’s shape. The topic comes up so routinely that physicists have fielded it in Q-and-A forums, pointing out that the phrase is just an engineering convenience.
RP-1207 walks the reader through converting the full six-degree-of-freedom equations of
motion plus a nonlinear aerodynamic model into constant A, B,
C and D matrices. Those matrices let engineers:
Unlike earlier “toy” derivations, the report makes no symmetry or trajectory assumptions, so the recipe works for everything from fighters to transports.