propellant

also n.

1. Something, such as an explosive charge or a rocket fuel, that propels or provides thrust.
2. A compressed inert gas, such as a fluorocarbon, that acts as a vehicle for discharging the contents of an aerosol container.

adj.
Serving to propel; propelling.

Usually, a combustible substance that produces heat and supplies ejection particles, as in a rocket engine. A propellant is both a source of energy and a working substance; a fuel is chiefly a source of energy, and a working substance is chiefly a means for expending energy. Because the distinction is more decisive in rocket engines, the term propellant is used primarily to describe chemicals carried by rockets for propulsive purposes. See also Aircraft fuel; Rocket propulsion.

Propellants are classified as liquid or as solid. Even if a propellant is burned as a gas, it may be carried under pressure as a cryogenic liquid to save space. For example, liquid oxygen and liquid hydrogen are important high-energy liquid bipropellants.

Liquid propellants

A liquid propellant releases energy by chemical action to supply motive power for jet propulsion. The three principal types of propellants are monopropellant, bipropellant, and hybrid propellant. Monopropellants are single liquids, either compounds or solutions. Bipropellants consist of fuel and oxidizer carried separately in the vehicle and brought together in the engine. Hybrid propellants use a combination of liquid and solid materials to provide propulsion energy and working substance. Typical liquid propellants are listed in the table. See also Metal-base fuel.

Physical properties of liquid propellants

Propellant	Boiling point, °F (°C)	Freezing point, °F (°C)	Density g/ml	Specific impulse,* s
Monopropellants
Acetylene	−119 (−84)	−115 (−82)	0.62	265
Hydrazine	236 (113)	35 (2)	1.01	194
Ethylene oxide	52 (11)	−168 (−111)	0.88	192
Hydrogen peroxide	288 (142)	13 (−11)	1.39	170
Bipropellants
Hydrogen	−423 (−253)	−433 (−259)	0.07
Hydrogen-fluorine	−306 (−188)	−360 (−218)	1.54	410
Hydrogen-oxygen	−297 (−183)	−362 (−219)	1.14	390
Nitrogen tetroxide	70 (21)	12 (−11)	1.49	—
Nitrogen-tetroxide-hydrazine	236 (113)	35 (2)	1.01	290
Red nitric acid	104 (40)	−80 (−62)	1.58
Red fuming nitric acid–uns-dimethyl hydrazine	146 (63)	−71 (−57)	0.78	275

*Maximum theoretical specific impulse at 1000 psi (6.895 megapascals) chamber pressure expanded to atmospheric pressure.

The availability of large quantities and their high performance led to selection of liquefied gases such as oxygen for early liquid-propellant rocket vehicles. Liquids of higher density with low vapor pressure (see table) are advantageous for the practical requirements of rocket operation under ordinary handling conditions. Such liquids can be retained in rockets for long periods ready for use and are convenient for vehicles that are to be used several times. The high impulse of the cryogenic systems is desirable for rocket flights demanding maximum capabilities, however, such as space exploration or transportation of great weights for long distances.

Solid propellants

A solid propellant is a mixture of oxidizing and reducing materials that can coexist in the solid state at ordinary temperatures. When ignited, a propellant burns and generates hot gas. Although gun powders are sometimes called propellants, the term solid propellant ordinarily refers to materials used to furnish energy for rocket propulsion.

A solid propellant normally contains three essential components: oxidizer, fuel, and additives. Oxidizers commonly used in solid propellants are ammonium and potassium perchlorates, ammonium and potassium nitrates, and various organic nitrates, such as glyceryl trinitrate (nitroglycerin). Common fuels are hydrocarbons or hydrocarbon derivatives, such as synthetic rubbers, synthetic resins, and cellulose or cellulose derivatives. The additives, usually present in small amounts, are chosen from a wide variety of materials and serve a variety of purposes. Catalysts or suppressors are used to increase or decrease the rate of burning; ballistic modifiers may be used for a variety of reasons, as to provide less change in burning rate with pressure (platinizing agent); stabilizers may be used to slow down undesirable changes that may occur in tong-term storage.

Solid propellants are classified as composite or double base. The composite types consist of an oxidizer of inorganic salt in a matrix of organic fuels, such as ammonium perchlorate suspended in a synthetic rubber. The double-base types are usually high-strength, high-modulus gels of cellulose nitrate (guncotton) in glyceryl trinitrate or a similar solvent.

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n. 1. the source (specifically, an explosive charge) that provides the energy required for propelling a projectile.

2. a fuel, either solid or liquid, for propelling a rocket or missile.

See the Introduction, Abbreviations and Pronunciation for further details.

IN BRIEF: Something that causes another thing to move forward.

They used jet fuel for rocket propellant in the first tests.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - drivmiddel, drivstof, drivladning
adj. - fremdrivende

Nederlands (Dutch)
brandstof, voortstuwend

Français (French)
n. - gaz propulseur, propergol, poudre propulsive
adj. - propulseur

Deutsch (German)
n. - Treibstoff, Treibgas
adj. - Antriebs-

Ελληνική (Greek)
n. - προωθητήρια ή προωστική ουσία, καύσιμα πυραύλου
adj. - προωστικός, προωθητικός

Italiano (Italian)
propulsore

Português (Portuguese)
n. - propulsor (m)
adj. - propulsor

Русский (Russian)
приводящий в движение

Español (Spanish)
n. - propulsor, propergol
adj. - propulsor, propergol

Svenska (Swedish)
n. - drivmedel, bränsle, drivkraft
adj. - framdrivande, driv-

中文（简体）(Chinese (Simplified))
使推进之物, 推进燃料, 发射火药, 推进的

中文（繁體）(Chinese (Traditional))
n. - 使推進之物, 推進燃料, 發射火藥
adj. - 推進的

한국어 (Korean)
n. - 추진시키는 것
adj. - 추진하는

日本語 (Japanese)
n. - 推進燃料, 発射火薬
adj. - 推進させる

العربيه (Arabic)
‏(الاسم) وقود, عبوة دافعه في قنبله (صفه) ما يخص الوقود أو العبوة‏

עברית (Hebrew)
n. - ‮נוזל דחוס של מרסס, חומר-נפץ הודף, חומר-הדף במנוע של רקטה‬
adj. - ‮דוחף‬

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