Ablation rate calculation of thermal insulations in segmented solid propellant rocket motors = Etude de l'ablation de protections thermiques dans un propulseur a propergol solide segmente (: Communication... AIAA/SAE/ASME/ASEE 29th joint propulsion conference and exhibit, published by AIAA (AIAA 93-1884), Monterey, CA (USA), June 28-30, 1993)