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 μm, density comprised between 0.30 and 0.34 g/cc and resistance to hydrostatic pressure greater than, or equal to, 4500 psi.

Solid propellant systems include a main propellant and a secondary propellant in contact with the first propellant that exhibits autoignition temperatures of at least about 100° F. lower than the autoignition temperature of the main propellant. The secondary propellant of the present invention is most advantageously employed with conventional AP-containing solid propellant formulations as the main propellant, especially formulations containing both AP, an energetic solid, and a binder. In especially preferred forms, the secondary propellant will include a nitramine which is at least one selected from nitroguanidine (NQ), cyclotrimethylene trinitramine (RDX) and cyclotetramethylenetetranitramine (HMX), and a binder which is at least one selected from HTPB, HTPE or glycidyl azide polymer (GAP). Most preferably, the secondary propellant will include a combination of nitramines which includes NQ and one of RDX or HMX.

Solid propellant systems include a main propellant and a secondary propellant in contact with the first propellant that exhibits autoignition temperatures of at least about 100° F. lower than the autoignition temperature of the main propellant. The secondary propellant of the present invention is most advantageously employed with conventional AP-containing solid propellant formulations as the main propellant, especially formulations containing both AP, an energetic solid, and a binder. In especially preferred forms, the secondary propellant will include a nitramine which is at least one selected from nitroguanidine (NQ), cyclotrimethylene trinitramine (RDX) and cyclotetramethylenetetranitramine (HMX), and a binder which is at least one selected from HTPB, HTPE or glycidyl azide polymer (GAP). Most preferably, the secondary propellant will include a combination of nitramines which includes NQ and one of RDX or HMX.

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.

The present invention relates to the design and manufacture of an ignitable solid, where the solid is composed of an array of ignitable regions. In some examples, the array provides a three-dimensional periodic arrangement of such ignitable regions. The ignitable region can have any useful geometry and geometric arrangement within the solid, and methods of making such regions are also described herein.

Solid propellant systems include a main propellant and a secondary propellant in contact with the first propellant that exhibits autoignition temperatures of at least about 100° F. lower than the autoignition temperature of the main propellant. The secondary propellant of the present invention is most advantageously employed with conventional AP-containing solid propellant formulations as the main propellant, especially formulations containing both AP, an energetic solid, and a binder. In especially preferred forms, the secondary propellant will include a nitramine which is at least one selected from nitroguanidine (NQ), cyclotrimethylene trinitramine (RDX) and cyclotetramethylenetetranitramine (HMX), and a binder which is at least one selected from HTPB, HTPE or glycidyl azide polymer (GAP). Most preferably, the secondary propellant will include a combination of nitramines which includes NQ and one of RDX or HMX.

A propellant manufacturing method for manufacturing a propellant including a propellant grain having a first surface on which combustion starts upon ignition and a second surface to be coupled to a wall surface that prevents combustion. The manufacturing method includes placing a portion of first propellant having a first burning rate in a first space containing a first position on the second surface; and placing a portion of second propellant having a second burning rate higher than the first burning rate in a second space containing a second position on the first propellant. The method further includes placing a portion of third propellant having a third burning rate higher than the second burning rate in a third space containing a third position on the first propellant. The method further includes completing the propellant grain by simultaneously hardening the entireties of the first propellant, the second propellant, and the third propellant.

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.

The invention is directed to a method for the preparation of an energetic material product such as a propellant or explosive charge or grain, wherein said method comprises additive manufacturing comprising co-extrusion of at least two materials to form a multi-layered filament and layer-by-layer deposition of said multi-layered filament, wherein said multi-layered filament comprises a first material layer and a second material layer of which at least one comprises an energetic material. In another aspect, the invention is directed to an apparatus for use in this method, said apparatus comprising a co-extrusion nozzle

The invention is directed to a method for the preparation of an energetic material product such as a propellant or explosive charge or grain, wherein said method comprises additive manufacturing comprising co-extrusion of at least two materials to form a multi-layered filament and layer-by-layer deposition of said multi-layered filament, wherein said multi-layered filament comprises a first material layer and a second material layer of which at least one comprises an energetic material. In another aspect, the invention is directed to an apparatus for use in this method, said apparatus comprising a co-extrusion nozzle