Explicit guidance equations for maneuvering re-entry vehicles

The "characteristic curve" approach for deriving explicit re-entry guidance equations for Maneuvering Re-entry Vehicles (MaRVs) is developed, showing how terminal trajectory constraints on path angles and lift acceleration and its derivatives can be obtained. Variable gains for vector guidance equations are established by forcing terminal equation structure to be similar to the characteristic curve equations. Natural variations in the forms to the vector equations are shown. A linearized analysis of terminal steering in the presence of autopilot lag employs the solution of the resulting time-variant third order control equation. Converting the outputs of the guidance equations to autopilot commands for MaRVs with different numbers of control axes is shown. Using the explicit equations to achieve desired trajectory shapes is discussed along with practical considerations in their use.