A vacuum insulated blast tube includes an insulating layer of a burn resistant material such as phenolic resin formed on an interior surface of the blast tube to provide the necessary erosion and thermal insulation properties to protect the blast tube and a vacuum insulated layer formed in the walls of the blast tube itself to provide the additional thermal insulation properties to protect any non-propulsive sub-systems positioned in the void space around the blast tube. A void space in the walls of the blast tube is held under vacuum with a pressure of less than 25 Torr and a thermal conductivity Tcond_vac of less than one-third of the thermal conductivity of air Tcond_air to form the vacuum insulation layer.

A rocket motor may include a combustion chamber configured to carry propellant for propelling the rocket. The rocket motor may include a motor case enclosing the combustion chamber, the motor case comprising an external wall that has an insulator-carrying surface. The rocket motor may include an ablative layer carried by the insulator-carrying surface of the wall of the motor case. The rocket motor may include a set of surface structures on the insulator-carrying surface. The set of surface structures are shaped to provide mechanical retention of the ablative layer. The motor case may include an internal wall that is spaced apart from the external wall to form a passage space between the internal wall and the external wall. The ablative layer is located in the passage space. The external wall and the internal wall may be a monolithic piece formed from an additive manufacturing process.

A rocket motor may include a combustion chamber configured to carry propellant for propelling the rocket. The rocket motor may include a motor case enclosing the combustion chamber, the motor case comprising an external wall and an internal wall. The rocket motor may include an ablative layer. The motor case may include a metallic liner structure that is configured to be in contact with the propellant grain, the metallic liner structure has a mechanical strength that is within 50% and 400% of a mechanical strength of the propellant grain.

The invention relates to a method for assembling a first metal part with a second part made of an organic matrix composite material, the first part having a first connecting portion and the second part having a second connecting portion, the method comprising the steps of: causing the first connecting portion and the second connecting portion to overlap, a through-hole of the second connecting portion opening onto the first connecting portion, forming a protective layer on the side wall of the through-hole, forming a seal between the protective layer and the first connecting portion, and forming, by additive manufacturing using cold gas spray deposition of metal powder, a fastening element which extends into the through-hole, is fastened to the first connecting portion and encloses the second connecting portion.

A precursor composition comprising, before curing, ethylene propylene diene monomer (EPDM), an aramid, and a carbon material comprising carbon nanotubes, graphite, or a combination thereof. A rocket motor including a reaction product of the precursor composition and a method of insulating a rocket motor are also disclosed.

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.

An insulation precursor composition comprises ethylene propylene diene monomer, an aramid, and a bromine-containing flame retardant. Rocket motors comprising a case, an energetic material within the case, and an insulation material comprising a reaction produce of ethylene propylene diene monomer, an aramid, and a flame retardant comprising bromine are also disclosed. Related precursor compositions are also disclosed.

A method of making an ceramic article according to an exemplary embodiment of this disclosure, among other possible things includes arranging fiber plies into a preform, inserting one or more sacrificial springs to the preform, infiltrating the preform with a matrix material to form an article, and thermally degrading the one or more sacrificial springs to form cooling holes. A ceramic article and a gas turbine engine component are also disclosed.