A rocket motor includes a case and first and second nozzles in the case. The first nozzle is disposed in the second nozzle. The first nozzle includes a forward leg, a rear leg, and an intermediate leg. The intermediate leg has a convex conical geometry, and the forward leg has a forward lip that is spaced from the case. The rear leg has a rear lip that is spaced from the case. The forward leg and the rear leg at least partially define a flow passage through the first nozzle. The first nozzle is exclusively secured by the intermediate leg to at least one of the case or the second nozzle. At least a portion of a fragmentation system is disposed between the first and second nozzles.

A liquid rocket engine assembly comprising a thrust chamber, a nozzle, and a joint structure. The joint structure attaches the thrust chamber and the nozzle and comprises at least one seal element and an attachment ring interposed between the thrust chamber and the nozzle. Fasteners extend between the nozzle and the thrust chamber through the at least one seal element and the attachment ring. Materials of the thrust chamber and of the nozzle comprise different coefficients of thermal expansion. A method of forming a liquid rocket engine assembly is also disclosed.

A flexible bearing assembly includes at least one metal end ring, a flexible bearing core having a plurality of layers of a resilient material between layers of a reinforcement material, and a phenolic composite material between and bonded to each of the at least one metal end ring and the flexible bearing core. A rocket motor assembly includes a chamber configured to contain a propellant and a movable thrust nozzle coupled to the chamber. The movable thrust nozzle includes a phenolic composite material between and bonded to each of a metal end ring and a flexible bearing core. Methods of forming a flexible bearing assembly include bonding a phenolic composite material to at least one metal end ring and bonding a flexible bearing core to the phenolic composite material. The flexible bearing core includes a plurality of layers of a resilient material between layers of a reinforcement material.

A solid rocket motor includes a case, a solid propellant, and a seal attached to the motor. The seal isolates the solid propellant from a fluid external of the case, and the seal is at least partially transparent.

A thruster has an additively-manufactured housing that includes an integrally-formed nozzle with a burst disk in it. The housing is part of a casing that surrounds and encloses a propellant that is burned to produce pressurized gases that burst the burst disk and produce thrust. The thruster may be placed in a receptacle that defines a recess for receiving the thruster. The receptacle also may be additively manufactured. The thruster and the recess both may be cylindrical, with the housing being closely fit with the cylindrical walls of the receptacle. This may allow some of the structural loads on the housing, such as loads produced by the combustion of the propellant, to be transferred to the adjoining walls of the receptacle. This enables the housing to have less structural strength than if it were to have to contain the pressure from the propellant all on its own.

A motor assembly is provided for use with projectiles, such as munitions, having relatively low length to diameter ratios. The motor assembly has an aerospike nozzle and a casing disposed about the aerospike nozzle, where interior aerospike volume contains propellant and where walls of both the cowl of the casing and of the aerospike nozzle jointly define a combustion chamber.

Systems and methods for subscale testing of rocket engine injector stability. The system includes a combustion chamber and a piston within the chamber that is continuously axially moveable via an actuator. An annular gap between the piston and a chamber sidewall provides a minimal cross-sectional flow area. A modular injector plate comprises one or more injector elements configured to inject a fuel and an oxidizer into the chamber. The piston is continuously translated, to thereby continuously vary a combustion volume of the chamber and to create a dynamically tunable downstream boundary. The injector elements are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine. The injector plate is removably attached to an upstream end of the chamber for replacement of the first injector elements with different, second injector elements for subsequent testing.

A valve includes a valve body that has a flow path that connects the inlet and the outlet. A seal is disposed in the flow path. The seal has a closed state so as to block flow through the flow path and an open state so as to permit flow through the flow path. An armature is disposed in the valve body and is moveable with respect to the seal. An electromagnet is configured to selectively receive an electric current in a first current direction or a second, opposite current direction. When the electric current is in the first current direction the electromagnet actuates the armature to move the seal from closed to open and when the electric current is in the second current direction the electromagnet magnetically actuates the armature to move the seal from the open to closed.

Systems and methods for subscale testing of rocket engine injector stability. The system includes a combustion chamber with telescoping throat that is continuously axially moveable via an actuator. A modular injector plate comprises one or more first rocket engine injector elements configured to inject one or more propellants, such as a fuel and an oxidizer, into the chamber. The injector plate and/or the telescoping throat may be continuously translated, to thereby continuously vary a combustion volume of the chamber and create a dynamically tunable downstream boundary. The injectors are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine. The injector plate is removably attached to an upstream end of the chamber for replacement of the first injectors with different, second injectors for subsequent testing.

Systems and methods for subscale testing of rocket engine injector stability. The system includes a combustion chamber and a piston within the chamber that is continuously axially moveable via an actuator. An annular gap between the piston and a chamber sidewall provides a minimal cross-sectional flow area. A modular injector plate comprises one or more injector elements configured to inject a fuel and an oxidizer into the chamber. The piston is continuously translated, to thereby continuously vary a combustion volume of the chamber and to create a dynamically tunable downstream boundary. The injector elements are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine. The injector plate is removably attached to an upstream end of the chamber for replacement of the first injector elements with different, second injector elements for subsequent testing.