A solid propellant propulsion motor may comprise: a forward propellant grain extending along a longitudinal axis of a motor case between a forward end of the motor case and a first burn inhibitor layer in the motor case; the first burn inhibitor layer disposed axially adjacent to the forward propellant grain; an aft propellant grain disposed axially adjacent to the first burn inhibitor layer; a second burn inhibitor layer disposed axially adjacent to an aft end of the aft propellant grain; and an ablative material layer disposed on a radially inner surface of the aft propellant grain.

A solid propellant propulsion motor may comprise: a forward propellant grain extending along a longitudinal axis of a motor case between a forward end of the motor case and a first burn inhibitor layer in the motor case; the first burn inhibitor layer disposed axially adjacent to the forward propellant grain; an aft propellant grain disposed axially adjacent to the first burn inhibitor layer; a second burn inhibitor layer disposed axially adjacent to an aft end of the aft propellant grain; and an ablative material layer disposed on a radially inner surface of the aft propellant grain.

A rocket motor comprises at least two propellant grains/grain segments; a case comprising the propellant grains/grain segments, stacked within the case; and a resin for substantially maintaining the grains/grain segments in position within the case. In another aspect, a rocket motor comprises at least two propellant grains/grain segments, each having an aft-end face and a fore-end face. At least two of the propellant grains/grain segments comprise a sleeve having propellant cast therein. The motor further comprises a case comprising the propellant grains/grain segments, stacked within the case, wherein the sleeve of one propellant grain/grain segment is coupled to the sleeve of an adjacent propellant grain/grain segment such that the fore-end face of one grain/grain segment is spaced from the aft-end face of an other grain/grain segment creating a gap therebetween. Methods for making the rocket motors are described.

A rocket motor (20) includes a nozzle (22) and a solid propellant section (24) in communication with the nozzle. The solid propellant section includes a first energetic grain layer (38, 32) that has a top surface and a bottom surface, and a second energetic grain layer (40, 44) that has a top surface and a bottom surface. The second layer is located on top of the first layer. The bottom surface of the second energetic grain layer partially abuts the top surface of the first energetic grain layer, and the bottom surface of the second energetic grain layer and the top surface of the first energetic grain layer define a region (46, 48) therebetween. A powder energetic (49) is disposed in the region.

A rocket motor (20) includes a nozzle (22) and a solid propellant section (24) in communication with the nozzle. The solid propellant section includes a first energetic grain layer (38, 32) that has a top surface and a bottom surface, and a second energetic grain layer (40, 44) that has a top surface and a bottom surface. The second layer is located on top of the first layer. The bottom surface of the second energetic grain layer partially abuts the top surface of the first energetic grain layer, and the bottom surface of the second energetic grain layer and the top surface of the first energetic grain layer define a region (46, 48) therebetween. A powder energetic (49) is disposed in the region.

A method of forming a flexible structure for a rocket motor assembly comprises forming a polysiloxane composition comprising at least two different silicone materials. A preliminary structure is formed from the polysiloxane composition. The preliminary structure is cured to crosslink at least a portion of different polysiloxane chains of the preliminary structure. A flexible structure for a rocket motor assembly, a flexible assembly for a rocket motor assembly, a moveable thrust nozzle assembly for a rocket motor assembly, and a rocket motor assembly are also described.

A hybrid rocket solid fuel grain having a cylindrical shape and defining a center port is additive manufactured from a compound of thermoplastic fuel and passivated nanocomposite aluminum additive. The fuel grain comprises a stack of fused layers, each layer formed as a plurality of fused abutting concentric circular beaded structures arrayed to define a center port. During operation, an oxidizer is introduced along the center port, with combustion occurring along the exposed port wall. Each circular beaded structure defines geometry that increases the surface area available for combustion. As each layer ablates the next 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. To safely achieve this construction, a fused deposition additive manufacturing apparatus, modified to shield the nanocomposite material from the atmosphere, is used.

A hybrid rocket solid fuel grain having a cylindrical shape and defining a center port is additive manufactured from a compound of thermoplastic fuel and passivated nanocomposite aluminum additive. The fuel grain comprises a stack of fused layers, each layer formed as a plurality of fused abutting concentric circular beaded structures arrayed to define a center port. During operation, an oxidizer is introduced along the center port, with combustion occurring along the exposed port wall. Each circular beaded structure defines geometry that increases the surface area available for combustion. As each layer ablates the next 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. To safely achieve this construction, a fused deposition additive manufacturing apparatus, modified to shield the nanocomposite material from the atmosphere, is used.

The invention is directed to a propellant charge, to a method of preparing a propellant charge, and to uses of the propellant charge. The propellant charge or grain of the invention comprises two or more energetic materials with different linear burn rate, wherein the two or more energetic materials are distributed within the charge or grain such that two perpendicular cross-sections of said propellant charge or grain have at least two linear burn rate gradients in non-parallel directions, wherein said propellant charge or grain is layered with layers having a layer thickness in the range of 1-10 000 m, wherein, if the propellant charge or grain has a longitudinal axis, at least one of said perpendicular cross-sections is along said longitudinal axis, and wherein said propellant charge or grain further comprises one or more perforations.

A gas generator includes an outer propellant, an inner propellant arranged inside the outer propellant, and a barrier membrane which isolates the outer propellant from the inner propellant. A forward end surface of the inner propellant faces a combustion space. A side surface of the inner propellant is isolated from the combustion space.