A pulsed rocket motor is typically defined as a multiple-

pulse In medicine, the pulse refers to the rhythmic pulsations (expansion and contraction) of an artery in response to the cardiac cycle (heartbeat). The pulse may be felt ( palpated) in any place that allows an artery to be compressed near the surfac ...

solid-fuel rocket A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses Rocket propellant#Solid chemical propellants, solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder. The incepti ...

motor. This

design A design is the concept or proposal for an object, process, or system. The word ''design'' refers to something that is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something ...

overcomes difficulties shutting down and reigniting

solid propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, th ...

motors. The pulse rocket motor allows the motor to be burned in segments (or pulses) that burn until completion of that segment. The next segment can be ignited on command by either an onboard

algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

or in a pre-planned sequence. All of the segments are contained in a single rocket motor case, as opposed to staged rocket motors. The pulsed rocket motor is made by pouring each segment of propellant separately. Between each segment is a barrier that prevents the other segments from burning until ignited. At ignition of a second pulse, the burning of the propellant generally destroys the barrier. The benefit of the pulsed rocket motor is that, by the on-command ignition of the subsequent pulses, near-optimal energy management of the propellant burn can be accomplished. Each pulse can have a different thrust level and

burn time A burn is an injury to skin, or other tissues, caused by heat, electricity, chemicals, friction, or ionizing radiation (such as sunburn, caused by ultraviolet radiation). Most burns are due to heat from hot fluids (called scalding), solids, ...

, and achieve a different specific impulse depending on the type of propellant used, its burn rate, its grain design, and the current nozzle throat diameter.

Examples

Solid rocket motors are prized in military for their long shelf lives, but at the same time some control of the burn is desired. For example, the range of a missile can be extended by separating the burn into two pulses, one starting at launch and the other much later in its journey. Doing so would reduce the velocity of the missile during the majority of the course, therefore reducing losses to drag. The Chinese

PL-15 The PL-15 ( zh, s=霹雳-15, p=Pī Lì-Yāo Wǔ, l=Thunderbolt-15, NATO reporting name: CH-AA-10 Abaddon) is an active radar homing, active radar-guided long-range beyond-visual-range air-to-air missile developed by the People's Republic of Chi ...

air-to-air missile uses a dual-pulse motor. The American

SM-3 The RIM-161 Standard Missile 3 (SM-3) is a ship-based surface-to-air missile used by the United States Navy to intercept ballistic missiles as a part of Aegis Ballistic Missile Defense System. Although primarily designed as an anti-ballistic mis ...

surface-to-air missile uses a dual-pulse motor in its third stage, one before nosecone ejection, the other after. The

kinetic kill vehicle A kinetic energy weapon (also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is a projectile weapon based solely on a projectile's kinetic energy to inflict damage to a target, inst ...

of the SM-3 also uses a multi-charge solid fuel design, though the fuel is used here to feed a

gas generator A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical. The term often refers to a device that uses a ...

Examples

References

See also