This disclosure describes various techniques and systems for rapid low-cost access to suborbital and orbital space and accommodation of acceleration of sensitive payloads to space. For example, a distributed gas injection system may be used in a ram accelerator to launch multiple payloads through the atmosphere. Additionally or alternatively, multiple projectiles may assemble during flight through the atmosphere to transfer and/or resources to another projectile.

This disclosure describes various techniques and systems for rapid low-cost access to suborbital and orbital space and accommodation of acceleration of sensitive payloads to space. For example, a distributed gas injection system may be used in a ram accelerator to launch multiple payloads through the atmosphere. Additionally or alternatively, multiple projectiles may assemble during flight through the atmosphere to transfer and/or resources to another projectile.

A fuel grain for a hybrid rocket engine includes multiple, concentric cylindrical layers of fuel grain material defining a combustion port extending axially through 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 concentric layers are bonded together. Each bead of fuel grain material includes a polymer based rocket fuel material and a nanoscale metallic material, and a composition of the beads of the fuel grain material varies along a radius of the cylindrical fuel grain.

A fuel grain for a hybrid rocket engine includes multiple, concentric cylindrical layers of fuel grain material defining a combustion port extending axially through 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 concentric layers are bonded together. Each bead of fuel grain material includes a polymer based rocket fuel material and a nanoscale metallic material, and a composition of the beads of the fuel grain material varies along a radius of the cylindrical fuel grain.

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.

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 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 hybrid rocket includes a housing having first and second ends, a solid-grain fuel material in the housing and defining a bore extending from end to end, two electrodes positioned adjacent to the fuel material to ignite the fuel material at the first end, a primary oxidizer port positioned at the first end to inject a primary oxidizer to flow in a downstream direction from the first end to the second end, a nozzle positioned at the second end and having a converging portion and a diverging portion, and a secondary oxidizer port to inject a secondary oxidizer downstream of the converging portion. The bore has a geometry configured to produce a hot-gas, fuel-rich mixture at the nozzle as the fuel material and primary oxidizer burn while flowing downstream. The diverging portion of the nozzle is configured to spontaneously combust the secondary oxidizer and the hot-gas, fuel-rich mixture.

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 includes a housing having first and second ends, a solid-grain fuel material in the housing and defining a bore extending from end to end, two electrodes positioned adjacent to the fuel material to ignite the fuel material at the first end, a primary oxidizer port positioned at the first end to inject a primary oxidizer to flow in a downstream direction from the first end to the second end, a nozzle positioned at the second end and having a converging portion and a diverging portion, and a secondary oxidizer port to inject a secondary oxidizer downstream of the converging portion. The bore has a geometry configured to produce a hot-gas, fuel-rich mixture at the nozzle as the fuel material and primary oxidizer burn while flowing downstream. The diverging portion of the nozzle is configured to spontaneously combust the secondary oxidizer and the hot-gas, fuel-rich mixture.