Editing Liquid-propellant rocket (section)

==Cooling==
{{main article|Rocket engine cooling}}
Injectors are commonly laid out so that a fuel-rich layer is created at the combustion chamber wall. This reduces the temperature there, and downstream to the throat and even into the nozzle and permits the combustion chamber to be run at higher pressure, which permits a higher expansion ratio nozzle to be used which gives a higher ''I{{sub|SP}}'' and better system performance.<ref>Rocket Propulsion elements - Sutton Biblarz, section 8.1</ref> A liquid rocket engine often employs [[regenerative cooling (rocketry)|regenerative cooling]], which uses the fuel or less commonly the oxidizer to cool the chamber and nozzle.