Chemical rockets are the most common type of high power rocket, typically creating a high speed exhaust by the combustion of fuel with an oxidizer . The stored propellant can be a simple pressurized gas or a single liquid fuel that disassociates in the presence of a catalyst ( monopropellant ), two liquids that spontaneously react on contact ( hypergolic propellants ), two liquids that must be ignited to react (like kerosene (RP1) and liquid oxygen, used in most liquid-propellant rockets ), a solid combination of fuel with oxidizer ( solid fuel ), or solid fuel with liquid or gaseous oxidizer ( hybrid propellant system ). Chemical rockets store a large amount of energy in an easily released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks.
