 dynam motion missil descend atmospher dynam motion missil descend atmospher method present comput rapidli accur dynam motion ballist-type missil descend atmospher equat motion separ set static trajectori equat angl attack set rotat equat describ oscillatori motion missil center graviti transform allow rotat equat written manner analog equat undamp oscil spring mass system mass equal uniti time variabl spring constant initi condit equat solv envelop maximum angl attack addit transform allow calcul complet oscillatori motion time trajectori function maximum angl attack time solut maximum angl attack missil descend atmospher constant speed reduc aerodynam damp neglect 