A cylindrically-shaped hybrid rocket engine solid fuel grain defines an axial combustion port. A fuel grain material comprises a compounded blend of thermoplastic fuel and aluminum. The fuel grain comprises fused stack layers, each layer comprising a plurality of fused abutting concentric beaded structures arrayed to define the combustion port; the port exhibits a rifling pattern or rifling inducing geometry along the port wall. When an oxidizer is introduced into the combustion port combustion occurs along the exposed port wall. Each beaded structure defines a geometry that increases the combustion surface area while inducing a vortex flow of oxidizer and fuel gas. As each layer ablates, an abutting layer exhibiting a similar geometry, is revealed, undergoes a gas phase change, and ablates. This process repeats and persists until oxidizer flow is terminated or the fuel grain material is exhausted. The fuel grain may be manufactured by an additive manufacturing process.

A method for manufacturing a solid propellant includes: forming a tool of layers of a first material wherein cuts in the layers form a first interior chamber in the tool; using the tool to mold a second material in the first interior chamber; removing the molded second material from the tool; using the molded second material to mold an interior chamber in a rocket propellant grain; and removing the molded second material from the rocket propellant grain.

A method for manufacturing a solid propellant includes: forming a tool of layers of a first material wherein cuts in the layers form a first interior chamber in the tool; using the tool to mold a second material in the first interior chamber; removing the molded second material from the tool; using the molded second material to mold an interior chamber in a rocket propellant grain; and removing the molded second material from the rocket propellant grain.

A method of manufacturing a multi-layered propellant grain is provided. The method of the present disclosure simplifies the setup necessary to produce multi-layered propellants by using industrial equipment that is more energy and space efficient than the machinery that is conventionally employed for such processes. The method comprises providing a first propellant formulation; providing a die configured to provide a structure having an outer shell and a hollow interior when material is extruded therethrough; extruding the first propellant formulation through said die, to produce a first propellant layer having an outer shell defining a hollow interior in the form channel having open ends; providing a second propellant formulation, said second propellant formulation being of low viscosity; injecting said second propellant formulation into said channel defined by said first propellant layer to form a second propellant layer disposed in said channel; and hardening said second propellant layer. The first and second propellant layers have different rates of burning.

A method of manufacturing a multi-layered propellant grain is provided. The method of the present disclosure simplifies the setup necessary to produce multi-layered propellants by using industrial equipment that is more energy and space efficient than the machinery that is conventionally employed for such processes. The method comprises providing a first propellant formulation; providing a die configured to provide a structure having an outer shell and a hollow interior when material is extruded therethrough; extruding the first propellant formulation through said die, to produce a first propellant layer having an outer shell defining a hollow interior in the form channel having open ends; providing a second propellant formulation, said second propellant formulation being of low viscosity; injecting said second propellant formulation into said channel defined by said first propellant layer to form a second propellant layer disposed in said channel; and hardening said second propellant layer. The first and second propellant layers have different rates of burning.

An inner coating layer for solid-propellant rocket engines, constituted by a material comprising from 45% to 55% wt. of a a cross-linkable, unsaturated-chain polymer base, from 11% to 13% wt. of silica, from 15% to 25% wt. of vulcanizing agents and plasticizers, from 5% to 7% wt. of aramid fiber and from 10% to 15% wt. of microspheres made of a material selected among glass, quartz and nano clay, having diameter lower than 200 gm, density comprised between 0.30 and 0.34 g/cc and resistance to hydrostatic pressure greater than, or equal to, 4500 psi.

A packaged explosive product may include packaging film, explosive product, and a detonating cord. The packaging film may form one or more casings that contain the explosive product. The packaging film and explosive product form a charge. The detonating cord may be positioned external the one or more casings in relation to the explosive product while being positioned axially internal in relation to the one or more charges.

Propellant charges or grains having printed layers of two or more energetic materials are described along with methods for preparing and using them.

Propellant charges or grains having printed layers of two or more energetic materials are described along with methods for preparing and using them.

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.