Editing Solid-propellant rocket (section)

==Basic concepts==
[[File:Solid-Fuel Rocket Diagram.svg|thumb|A simplified diagram of a solid-fuel rocket.{{ordered list
| list_style=margin:0;
| item_style=list-style-position:inside;
| A solid [[Rocket propellant#Solid chemical propellants|fuel-oxidizer mixture]] (propellant) is packed into the rocket, with a cylindrical hole in the middle.
| An [[Pyrotechnic initiator|igniter]] combusts the surface of the propellant.
| The cylindrical hole in the propellant acts as a [[combustion chamber]].
| The hot exhaust is choked at the throat, which, among other things, dictates the amount of thrust produced.
| Exhaust exits the rocket.
}}]]
A simple solid [[rocket motor]] consists of a casing, [[De Laval nozzle|nozzle]], grain ([[propellant charge]]), and [[igniter]].

The solid grain mass [[combustion|burns]] in a predictable fashion to produce exhaust gases, the flow of which is described by [[Taylor–Culick flow]]. The [[propelling nozzle|nozzle]] dimensions are calculated to maintain a design [[Rocket engine#Combustion chamber|chamber]] pressure, while producing [[thrust]] from the exhaust gases.

Once ignited, a simple solid rocket motor cannot be shut off, as it contains all the ingredients necessary for combustion within the chamber in which they are burned. More advanced solid rocket motors can be [[throttle]]d, or extinguished<ref>{{cite web|url=https://patents.google.com/patent/US8336287B1/en|title=Solid propellant rocket motor having self-extinguishing propellant grain and systems therefrom}}</ref> and re-ignited, by control of the nozzle geometry or through the use of vent ports. Further, [[pulsed rocket motors]] that burn in segments, and that can be ignited upon command are available.

Modern designs may also include a steerable nozzle for guidance, [[avionics]], recovery hardware ([[parachute]]s), [[self-destruct]] mechanisms, [[Auxiliary power unit|APUs]], controllable tactical motors, controllable divert and [[Spacecraft attitude control|attitude control]] motors, and thermal management materials.
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