Editing Liquid-propellant rocket (section)

== Types ==
Liquid rockets can be [[monopropellant rocket]]s using a single type of propellant, or [[bipropellant rocket]]s using two types of propellant.  [[Tripropellant rocket]]s using three types of propellant are rare. Liquid oxidizer propellants are also used in [[hybrid rocket]]s, with some of the advantages of a [[solid rocket]]. '''Bipropellant liquid rockets''' use a liquid [[fuel]] such as [[liquid hydrogen]] or [[RP-1]], and a liquid [[oxidizer]] such as [[liquid oxygen]]. The engine may be a [[cryogenic rocket engine]], where the fuel and oxidizer, such as hydrogen and oxygen, are gases which have been liquefied at very low temperatures.

Most designs of liquid rocket engines are [[Rocket engine throttling|throttleable]] for variable thrust operation. Some allow control of the propellant mixture ratio (ratio at which oxidizer and fuel are mixed). Some can be shut down and, with a suitable ignition system or self-igniting propellant, restarted.

[[Hybrid rocket]]s apply a liquid or gaseous oxidizer to a solid fuel.<ref name="Sutton"/>{{rp|354–356}}