A solid-fuel rocket assembly including an elongate fuel container having a long axis, and an inner surface spaced outwardly from, and generally circumsurrounding, that axis, and a continuous, elastomeric, heat-insulative, intumescence-behavior jacket adhered to the container's inner surface and defining a central chamber for receiving an elongate body of solid fuel. This structure implements a method for minimizing, in a solid-fuel rocket, heat damage to the wall of a solid-fuel container during burning of contained solid fuel including the steps of (a) producing dual-interface, continuous-presence, heat-insulative barriering in the zone existing between the container and burning fuel, with such barriering being characterized by (1) interfacially following any heat-produced deformations in the container wall, and (2) interfacially confronting the burning fuel with a tendency for intumescence-driven barrier-thickening.