Pressure variations within a solid propellant rocket motor produce like variations in the optical radiance of the motor exhaust plume. The periodicity of the variation is related to the length L of the rocket motor or speed of sound in the rocket motor combustion chamber to length ratio a/L. The optical radiance is collected and converted to electrical signals that are sampled at or above the Nyquist rate. An array of single-pixel photo detectors is well suited to provide amplitude data at high sample rates. The sampled data from the one or more detectors is assembled to form a high fidelity time sequence. A window of sampled data is processed to form a signal frequency spectrum. The mode structure in the frequency spectrum is related to the rocket motor length or speed of sound in the rocket motor chamber to length ratio. The rocket motor length or speed of sound to length ratio is used alone or in combination with other information to either classify or identify the rocket motor.

A rocket booster has an annular shape, with a casing defining an annular space therewithin, and a solid rocket fuel in the annular spacing. The casing may itself at least in part define an annular gap that functions as a nozzle for the rocket booster, with protruding tabs on the casing aiding in maintaining a uniform height of the annular gap. The rocket booster may be mechanically coupled to an object protruding from the back of a fuselage of a flight vehicle, such as a missile. For example, the rocket booster may be placed around an aft turbojet nozzle of the flight vehicle. This allows the rocket booster to be used in situations where primary propulsion must be running both before and after (and perhaps during) the firing of the rocket booster.

A rocket booster has an annular shape, with a casing defining an annular space therewithin, and a solid rocket fuel in the annular spacing. The casing may itself at least in part define an annular gap that functions as a nozzle for the rocket booster, with protruding tabs on the casing aiding in maintaining a uniform height of the annular gap. The rocket booster may be mechanically coupled to an object protruding from the back of a fuselage of a flight vehicle, such as a missile. For example, the rocket booster may be placed around an aft turbojet nozzle of the flight vehicle. This allows the rocket booster to be used in situations where primary propulsion must be running both before and after (and perhaps during) the firing of the rocket booster.

A rocket booster has an annular shape, with a casing defining an annular space therewithin, and a solid rocket fuel in the annular spacing. The rocket booster also includes one or more nozzle pieces, mechanically coupled to the casing, that define one or more nozzles at the aft side of the rocket booster. The rocket booster may be mechanically coupled to an object protruding from the back of a fuselage of a flight vehicle, such as a missile. For example, the rocket booster may be placed around an aft turbojet nozzle of the flight vehicle. This allows the rocket booster to be used in situations where primary propulsion must be running both before and after (and perhaps during) the firing of the rocket booster.

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 device may include an electrically-operated propellant or energetic gas-generating material, additively manufactured together with electrodes for producing a reaction in the material. The device may also include a casing that is additively manufactured with the other components. The additive manufacturing may be accomplished by extruding or otherwise depositing raw materials for the different components where desired. The electrodes may be made of a conductive polymer material, for example using an electrically-conductive fill in a polymer.

A vehicle comprising a structure, a plurality of heating sources, and a transport mechanism. The structure is comprised of multiple materials, a composite such that some of the material constituents can be extracted leaving behind others via application of energy (such as de-alloying). The extracted material or materials are configured to be re-purposed into a propellant. The plurality of heating elements surrounds or is embedded within the structure configured to convert the material into the propellant. The transport mechanism is configured to transport the propellant from the structure to a reservoir or to the propulsion system.

A precursor formulation comprising, before curing, a hydroxyl-terminated polybutadiene (HTPB) prepolymer or a hydroxyl-terminated polyether (HTPE) prepolymer, an oxidizer, a dimer fatty diol, and an isocyanate curative. A solid propellant comprising a reaction product of the HTPB prepolymer or HTPE prepolymer, the dimer fatty diol, and the isocyanate curative is also disclosed, as is a rocket motor comprising a case and a solid propellant in the case, the solid propellant comprising the reaction product and an oxidizer. A method of reducing a burn rate of a solid propellant is also disclosed.

A precursor formulation comprising, before curing, a hydroxyl-terminated polybutadiene (HTPB) prepolymer or a hydroxyl-terminated polyether (HTPE) prepolymer, an oxidizer, a dimer fatty diol, and an isocyanate curative. A solid propellant comprising a reaction product of the HTPB prepolymer or HTPE prepolymer, the dimer fatty diol, and the isocyanate curative is also disclosed, as is a rocket motor comprising a case and a solid propellant in the case, the solid propellant comprising the reaction product and an oxidizer. A method of reducing a burn rate of a solid propellant is also disclosed.