A rocket motor comprising: a case; a nozzle system including first and second nozzles (126,128) disposed in the case, the first nozzle at least partially disposed in the second nozzle; and a fragmentation system (134; 234), at least a portion of which is disposed between the first and second nozzles; wherein the first nozzle includes: a convergent section that narrows to a throat section that expands to a divergent section, a forward leg forming the convergent section, a rear leg forming the divergent section, and an intermediate leg between the forward leg and the rear leg, wherein the rear leg has a rear lip that is spaced from the case such that there is a rear gap between the rear lip and the case, the forward leg and the rear leg at least partially defining a flow passage through the first nozzle; characterised in that: the intermediate leg has a convex conical geometry; the forward leg has a forward lip that is spaced from the case such that there is a forward gap between the forward lip and the case, and the first nozzle is exclusively secured by the intermediate leg to at least one of the case or the second nozzle. a case; a nozzle system including first and second nozzles (126,128) disposed in the case, the first nozzle at least partially disposed in the second nozzle; and a fragmentation system (134; 234), at least a portion of which is disposed between the first and second nozzles; wherein the first nozzle includes: a convergent section that narrows to a throat section that expands to a divergent section, a forward leg forming the convergent section, a rear leg forming the divergent section, and an intermediate leg between the forward leg and the rear leg, wherein the rear leg has a rear lip that is spaced from the case such that there is a rear gap between the rear lip and the case, the forward leg and the rear leg at least partially defining a flow passage through the first nozzle; characterised in that: the intermediate leg has a convex conical geometry; the forward leg has a forward lip that is spaced from the case such that there is a forward gap between the forward lip and the case, and the first nozzle is exclusively secured by the intermediate leg to at least one of the case or the second nozzle. a convergent section that narrows to a throat section that expands to a divergent section, a forward leg forming the convergent section, a rear leg forming the divergent section, and an intermediate leg between the forward leg and the rear leg, wherein the rear leg has a rear lip that is spaced from the case such that there is a rear gap between the rear lip and the case, the forward leg and the rear leg at least partially defining a flow passage through the first nozzle; characterised in that: the intermediate leg has a convex conical geometry; the forward leg has a forward lip that is spaced from the case such that there is a forward gap between the forward lip and the case, and the first nozzle is exclusively secured by the intermediate leg to at least one of the case or the second nozzle. the intermediate leg has a convex conical geometry; the forward leg has a forward lip that is spaced from the case such that there is a forward gap between the forward lip and the case, and the first nozzle is exclusively secured by the intermediate leg to at least one of the case or the second nozzle.