Solid propellant designed to burn centripetally and its use in rocket engines or other motors

A solid cylindrical externally burning propellant element adapted to be fixed in a propulsion device, having substantially constant burning surface, said element having a cross section such that it may be inscribed in a cylinder of radius R, and longitudinal axis O, the cross section of said element exhibiting rotational symmetry of order n about said longitudinal axis of the element, wherein n is an integer number greater than or equal to 2, the cross section of the element having a contour consisting of identical and convoluted lobes, wherein n is as defined hereinabove, each of said lobes being connected to its adjacent lobes, the portions of the lobes which are the farthest from the axis O of said cylinder of radius R being curved and consisting of semicircular arcs of radius e, wherein e is the combustion thickness of the element, each of said semicircular arcs being tangential to said cylinder of radius R at a point which coincides with one end of the said semi-circular arcs, each of said semicircular arcs being extended by a convex arc of a circle of radius at least equal to 2e, each of said convex arcs being tangential to said cylinder of radius R, at the same point at which each of said semicircular arcs is tangential to said cylinder of radius R, said propellant element giving a single residue of polygonal shape, on combustion, said element being anchored in said propulsion device through attachment means set in the location of said residue, the external contour of said residue being situated at a distance e from the external contour of each lobe, e being as defined hereinabove.