A method of making a fuel grain for a hybrid rocket engine includes deposing beads of fuel grain material onto mandrel using additive manufacturing to form a cylindrical fuel grain, each bead including a polymer based rocket fuel material and a nanoscale metallic material. The deposing includes deposing multiple, adjacent beads to form concentric layers of beads, wherein a composition of the beads of the fuel grain material differs between the beads of a first layer and the beads of a second layer of the fuel grain.

A method of making a fuel grain for a hybrid rocket engine includes deposing beads of fuel grain material onto mandrel using additive manufacturing to form a cylindrical fuel grain, each bead including a polymer based rocket fuel material and a nanoscale metallic material. The deposing includes deposing multiple, adjacent beads to form concentric layers of beads, wherein a composition of the beads of the fuel grain material differs between the beads of a first layer and the beads of a second layer of the fuel grain.

A non-self-passivating fuel such as boron or magnesium is protected from exposure to oxygen sources by a self-passivating fuel layer such as aluminum or titanium. When the non-self-passivating fuel is utilized within a layered structure of alternating fuel and oxygen source layers, self-passivating fuel layers located between each non-self-passivating fuel layer and each oxygen source layer. The self-passivating fuel oxidizes until self-passivation is reached, protecting the non-self-passivating fuel from oxidation. Any of the non-self-passivating fuel which does not oxidize is available for use as fuel in any fuel-oxygen source reaction.

A non-self-passivating fuel such as boron or magnesium is protected from exposure to oxygen sources by a self-passivating fuel layer such as aluminum or titanium. When the non-self-passivating fuel is utilized within a layered structure of alternating fuel and oxygen source layers, self-passivating fuel layers located between each non-self-passivating fuel layer and each oxygen source layer. The self-passivating fuel oxidizes until self-passivation is reached, protecting the non-self-passivating fuel from oxidation. Any of the non-self-passivating fuel which does not oxidize is available for use as fuel in any fuel-oxygen source reaction.

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.

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 discrete gradient charge that has a discrete first hollow cylindrical layer of a solid first fuel, which is about 85% by weight fine aluminum powder having a median diameter of about 3.5 microns. There is a discrete second hollow cylindrical layer of a solid second fuel that is about 80% by weight coarse aluminum powder with a median diameter of about 31.0 microns. The fuels have a cured HTPB binder. A pellet of an explosive positioned within the first hollow cylindrical layer provides ignition. The fuel in the charge reacts with the surrounding air or with a hollow cylindrical oxidizer layer, or a combination thereof.

A reactive burning rate accelerator is provided that is configured to be at least partially embedded in a solid energetic material and comprises at least one metallic component and at least one non-metallic component. The reactive burning rate accelerator is configured to ignite and combust to increase the mass burning rate of the solid energetic material. Also provided are solid energetic materials comprising the reactive burning accelerator and methods of manufacturing and using the same.

A reactive burning rate accelerator is provided that is configured to be at least partially embedded in a solid energetic material and comprises at least one metallic component and at least one non-metallic component. The reactive burning rate accelerator is configured to ignite and combust to increase the mass burning rate of the solid energetic material. Also provided are solid energetic materials comprising the reactive burning accelerator and methods of manufacturing and using the same.

A solid propellant rocket motor may comprise a core-burning propellant grain extending along a longitudinal axis of the solid propellant rocket motor between an exhaust end of the solid propellant rocket motor and a forward end of the solid propellant rocket motor, a first burn inhibitor layer surrounding the core-burning propellant grain, an end-burning propellant grain surrounding the first burn inhibitor layer, a second burn inhibitor layer surrounding the end-burning propellant grain, and an aperture at least partially defined by the first burn inhibitor layer. The end-burning propellant grain is ignited by the core-burning propellant grain via the aperture.