From Citizendium - Reading time: 2 min
Rocket fuels are used to propel projectiles. Typically, expanding gases from the rapid combustion of the rocket fuel propels the rocket.[1]
Gunpowder was the first rocket fuel, first used in ancient China.[1]
Rockets are best known for their use in celebrations, and as weapons. Rockets have also been used in engineering, and by mariners, to carry a messenger line across a chasm, or between ships.[1] Starting in the 20th century, rockets have been used for transportation, carrying satellites or astronauts, to outer space.[2][3]
Rockets designed by pioneers like Robert Godard and Werner von Braun carried both a liquid fuel, and supercooled liquid oxygen, to enable particularly rapid combustion, and to allow the rockets to continue to burn even when the rocket had risen to high to use ambient atmospheric oxygen.[2][3]
Rockets that rely on solid fuel may have a solid oxidant mixed with the fuel.[2][3]
Rockets used in outer space may rely on hypergolic fuels, where two separate fuels ignite automatically, without an outside source of ignition, merely by mixing them in a combustion chamber.