A combustible element includes regions of fuel material interspersed with regions of oxidizer material. The element may be made by additive manufacturing processes, such as three-dimensional printing, with the fuel material regions and the oxidizer material regions placed in appropriate locations in layer of the combustible element. For example, different extruders may be used to extrude and deposit portions of a fuel filament and an oxidizer filament at different locations in each layer of the combustible element. The combustible element may define a combustion chamber within the element, where combustion occurs when the combustible element is ignited. The fuel material and the oxidizer material may be selected, and their relative amounts may be controlled, such that desired relative amounts of fuel and oxidizer are present for combustion with desired characteristics, such as combustion rate.

A combustible element includes regions of fuel material interspersed with regions of oxidizer material. The element may be made by additive manufacturing processes, such as three-dimensional printing, with the fuel material regions and the oxidizer material regions placed in appropriate locations in layer of the combustible element. For example, different extruders may be used to extrude and deposit portions of a fuel filament and an oxidizer filament at different locations in each layer of the combustible element. The combustible element may define a combustion chamber within the element, where combustion occurs when the combustible element is ignited. The fuel material and the oxidizer material may be selected, and their relative amounts may be controlled, such that desired relative amounts of fuel and oxidizer are present for combustion with desired characteristics, such as combustion rate.

An end-burning grain of a solid rocket motor or other gas-generating device is supplemented with one or more sticks of high-burn-rate propellant embedded in a matrix of a relatively low-burn-rate propellant. The sticks increase the burning surface area as the grain burns by forming conical indentations in the surface.

An end-burning grain of a solid rocket motor or other gas-generating device is supplemented with one or more sticks of high-burn-rate propellant embedded in a matrix of a relatively low-burn-rate propellant. The sticks increase the burning surface area as the grain burns by forming conical indentations in the surface.

Electrically operated propellant is used to supplement the thrust provided by solid rocket motor (SRM) propellant to manage thrust produced by a SRM. The gas produced by burning the electrically operated propellant may be injected upstream of the nozzle to add mass and increase chamber pressure Pc, injected at the throat of the nozzle to reduce the effect throat area At to increase chamber pressure Pc or injected downstream of the throat to provide thrust vector control or a combination thereof. Certain types of electrically operated propellants can be turned on and off provided the chamber pressure Pc does not exceed a self-sustaining threshold pressure eliminating the requirement for physical control valves.

Electrically operated propellant is used to supplement the thrust provided by solid rocket motor (SRM) propellant to manage thrust produced by a SRM. The gas produced by burning the electrically operated propellant may be injected upstream of the nozzle to add mass and increase chamber pressure Pc, injected at the throat of the nozzle to reduce the effect throat area At to increase chamber pressure Pc or injected downstream of the throat to provide thrust vector control or a combination thereof. Certain types of electrically operated propellants can be turned on and off provided the chamber pressure Pc does not exceed a self-sustaining threshold pressure eliminating the requirement for physical control valves.

A solid propellant rocket motor may comprise a core-burning propellant grain extending along a longitudinal axis of the solid propellant rocket motor between an exhaust end of the solid propellant rocket motor and a forward end of the solid propellant rocket motor, a first burn inhibitor layer surrounding the core-burning propellant grain, an end-burning propellant grain surrounding the first burn inhibitor layer, a second burn inhibitor layer surrounding the end-burning propellant grain, and an aperture at least partially defined by the first burn inhibitor layer. The end-burning propellant grain is ignited by the core-burning propellant grain via the aperture.

A solid propellant rocket motor may comprise a core-burning propellant grain extending along a longitudinal axis of the solid propellant rocket motor between an exhaust end of the solid propellant rocket motor and a forward end of the solid propellant rocket motor, a first burn inhibitor layer surrounding the core-burning propellant grain, an end-burning propellant grain surrounding the first burn inhibitor layer, a second burn inhibitor layer surrounding the end-burning propellant grain, and an aperture at least partially defined by the first burn inhibitor layer. The end-burning propellant grain is ignited by the core-burning propellant grain via the aperture.

The first solid propellant is formed to have a columnar shape so as for a combustion surface to move to a first direction, and to have an end surface exposed to a combustion space. The surface of first solid propellant except for the end surface is covered with a barrier membrane. The position of combustion surface in the first direction is detected by a position sensor device in an always-on measurement or a fixed-point measurement. Based on the detected result, the consumption amount of the first solid propellant is estimated.

The first solid propellant is formed to have a columnar shape so as for a combustion surface to move to a first direction, and to have an end surface exposed to a combustion space. The surface of first solid propellant except for the end surface is covered with a barrier membrane. The position of combustion surface in the first direction is detected by a position sensor device in an always-on measurement or a fixed-point measurement. Based on the detected result, the consumption amount of the first solid propellant is estimated.