AskDefine | Define propellant

Dictionary Definition

propellant adj : tending to or capable of propelling; "propellant fuel for submarines"; "the faster a jet plane goes the greater its propulsive efficiency"; "universities...the seats of propulsive thought" [syn: propellent, propelling, propulsive] n : something that propels [syn: propellent]

User Contributed Dictionary



  1. anything that propels
  2. a fuel or oxidizer for an engine, especially one for a rocket that provides thrust by explosive chemical reaction
  3. the compressed gas in an aerosol container


  1. capable of propelling

Extensive Definition

A propellant is a material that is used to move ("propel") an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid.
Common chemical propellants consist of a fuel, like gasoline, jet fuel and rocket fuel, and an oxidizer.

Aerosol sprays

In aerosol spray cans, the propellant is simply a pressurized vapour in equilibrium with its liquid. As some gas escapes to expel the payload, more liquid evaporates, maintaining an even pressure. (See aerosol spray propellant for more information.)

Solid propellant rockets and projectiles

In ballistics and pyrotechnics, a propellant is a generic name for chemicals used for propelling projectiles from guns and other firearms. Some explosive substances can be used both as propellants and as bursters, as for example gunpowder, and some of the ingredients of a propellant may be similar, though differently proportioned and combined, to those of an explosive. Propellants are nearly always chemically different from explosives as used in shells and mines to produce a blasting effect.
A very typical propellant burns rapidly but controllably and non explosively, to produce thrust by gas pressure and thus accelerates a projectile or rocket. In this sense, common or well known propellants include, for firearms, artillery and solid propellant rockets:
Propellants that explode in operation are of little practical use currently, although there have been experiments with Pulse Detonation Engines.

Liquid propellant rockets

Technically, the word propellants is used for the chemicals combined in a rocket engine to make it move by reactive force. However, amongst the English-speaking lay public, used to having fuels propel vehicles on Earth, the word fuel is inappropriately used. In Germany, the word Treibstoff—literally "drive-stuff"—is used; in France, the word ergols is used; it has the same Greek roots as hypergolic, a term used in English for propellants which combine spontaneously and do not have to be set ablaze by auxiliary ignition system.
Most common are bipropellant combinations, which use two chemicals, a fuel and an oxidiser. There is the possibility of a tripropellant combination, which takes advantage of the ability of substances with smaller atoms to attain a greater exhaust velocity, and hence propulsive efficiency, at a given temperature. Although not used in practice, the most developed theory involves adding a third propellant tank containing liquid hydrogen to do this. In practice, a hydrogen-oxygen engine can take advantage of this by simply adding more hydrogen than would obtain at the stoichiometric ratio.

Sources and references

propellant in German: Treibladung
propellant in Spanish: Propergol
propellant in French: Propergol
propellant in Indonesian: Bahan pendorong
propellant in Japanese: プロペラント
propellant in Portuguese: Propelente
propellant in Finnish: Ajoaine
propellant in Swedish: Drivämne
propellant in Vietnamese: Thuốc phóng
propellant in Italian: Propellente solido
propellant in Chinese: 裝藥

Synonyms, Antonyms and Related Words

active, airscrew, alcohol, benzine, briquette, burnable, butane, carbon, catalyst, charcoal, charge, coal, coke, combustible, dope, driver, driving, ethane, ethanol, exhaust, fan, fireball, firing, flammable, flammable material, fuel, fuel additive, fuel dope, gas, gas carbon, gasoline, heptane, hexane, impeller, impelling, impetus, impulse, in motion, incentive, incitation, inflammable, inflammable material, isooctane, jet fuel, jet propulsion, kerosene, liquid oxygen, methane, methanol, mobile, motile, motivation, motivational, motive, motor, moving, natural gas, octane, oil, paddle wheel, paraffin, peat, pentane, piston, prop, propane, propeller, propelling, propulsion charge, propulsive, propulsor, propulsory, provocative, pulsive, pushing, reaction propulsion, rocket fuel, rocket propulsion, rotor, screw, screw propeller, shoving, spur, stimulant, stirring, thrust, transitional, traveling, turbine, turf, twin screws, wheel
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