Ballistic re-entry vehicle dispersion due to precession stoppage

Ballistic re-entry vehicle (RV) precession stoppage phenomenon is investigated analytically and several postulated reasons for its occurrence are discussed. Both analytical solutions and six-degree-of-freedom (6DOF) simulations are presented. In addition to the familiar phenomena of roll near zero (RNZ) and angle-of-attack divergence, there are four additional aerodynamic forcing functions that are found to be particularly interesting and significant since they can induce the so-called "space-fixed-trim" phenomenon i.e., the lift vector becomes momentarily stationary in space. According to the present analytical/numerical results, the initial spin rate can be crucial for the magnitude as well as the direction of the RV dispersion. Finally, some possible physical mechanisms which would cause RV precession stoppage are suggested.