A method of producing a propellant material element, such as an electrically-operated propellant material, includes extruding a propellant material through a heated nozzle. The nozzle may be heated to a temperature that is above the boiling point of a solvent that is part of the propellant material, yet is below a decomposition temperature of the propellant material. This allows some of the solvent to be driven off during the extruding process, while still preventing initiation of an energy-creating reaction within the material. The heating of the material in the extruding process, and especially the heating of the nozzle that the material is extruded through, may be controlled to remove an amount of solvent that results in the extruded material having desirable properties.

A solid rocket motor includes a first solid propellant and a second solid propellant at least partially surrounding the first solid propellant. The second solid propellant is resistant to fragment impact and the first solid propellant has a higher impulse than the second solid propellant.

An additively manufactured solid fuel grain for a hybrid rocket engine having a cylindrical shape, defining a center combustion port and comprising a stack of fused layers of polymeric material suitable for hybrid rocket fuel. Each layer is formed as a plurality of fused abutting concentric beads of solidified material arrayed around the center port. An oxidizer is introduced into the solid fuel grain through the center port, with combustion occurring along the exposed surface area of the solid fuel grain center port wall. Each concentric bead possesses a surface pattern that increases the combustion surface area and when stacked forms a rifling pattern of undulations that induces oxidizer-fuel gas axial flow to improve combustion efficiency. The port wall surface pattern persists during the rocket engine's operation as the fuel phase changes from solid to gas and is ablated.

A fuel grain for a hybrid rocket engine includes multiple layers of fuel grain material defining a combustion port extending through a body of the fuel grain, in which each layer includes multiple beads of fuel grain material, in which the multiple beads in a given layer are disposed adjacent to one another and bonded together, and in which adjacent layers are bonded together, in which each bead of fuel grain material includes a polymer based rocket fuel material, and in which a composition of the beads of the fuel grain material, a form of the beads of fuel grain material, or both varies within the fuel grain.

A fuel grain for a hybrid rocket engine includes multiple layers of fuel grain material defining a combustion port extending through a body of the fuel grain, in which each layer includes multiple beads of fuel grain material, in which the multiple beads in a given layer are disposed adjacent to one another and bonded together, and in which adjacent layers are bonded together, in which each bead of fuel grain material includes a polymer based rocket fuel material, and in which a composition of the beads of the fuel grain material, a form of the beads of fuel grain material, or both varies within the fuel grain.

A solid rocket propellant grain having rocket propellant and a membrane in contact with the rocket propellant. The membrane includes a highly heat conductive pattern which affects the propellant burning rate through localized conductive heat transfer from the combustion zone and into the uncombusted propellant. Different geometries for the thermally conductive pattern produce different combustion results.

A method includes depositing beads of solid propellant material using additive manufacturing to form a fuel element for a rocket engine, the fuel element including beads of solid propellant material, wherein a combustion port extends through the fuel element, wherein the solid propellant material includes an oxidizer and a binder material.

A method includes depositing beads of solid propellant material using additive manufacturing to form a fuel element for a rocket engine, the fuel element including beads of solid propellant material, wherein a combustion port extends through the fuel element, wherein the solid propellant material includes an oxidizer and a binder material.