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Encyclopedia > Propellants

A propellant is a material that is used to move an object by applying a motive force. This may or may not involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid. Common propellants are gasoline, jet fuel and rocket fuel.

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Aerosol sprays

In aerosol cans, the propellant is simply a pressurized gas. If the can was simply filled with compressed gas, either it would need to be at a dangerously high pressure, or the amount of gas in the can would be small, and it would soon run out. Hence usually the gas is the vapour of a liquid with boiling point slightly lower than room temperature. This means that inside the pressurized can, the vapour can exist in equilibrium with its bulk liquid at a pressure that is higher than atmospheric pressure (and thus able to expel the payload), but not dangerously high; yet, as gas escapes, it is immediately replaced by more liquid evaporating.


Chlorofluorocarbons (CFCs) were once often used, but have been replaced in recent years due to the negative effects CFCs have on Earth's atmospheric ozone layer. The most common replacements are mixtures of volatile hydrocarbons, typically propane, n-butane and isobutane. Dimethyl ether (DME) and methylethyl ether are also used. All these have the principle disadvantage of being quite flammable. Nitrous oxide is also used as a propellant to deliver foodstuffs (e.g. whipped cream).


Solid fuelled rockets and projectiles

In ballistics and pyrotechnics, a propellant is a material which burns very rapidly but controllably, to produce thrust by gas pressure and thus accelerate a projectile or rocket. In this sense, common or well known propellants include, for firearms, artillery and solid fuel rockets:

Liquid fuelled rockets

Common propellants for liquid fuelled rockets include:

See also


  Results from FactBites:
 
Propeller Propulsion (546 words)
The engine takes air from the surroundings, mixes it with fuel, burns the fuel to release the energy in the fuel, and uses the heated gas exhaust to move a piston which is attached to a crankshaft.
The details are complex because the propeller acts like a rotating wing creating a lift force by moving through the air.
Propellers are not used on high speed aircraft.
Propeller Solutions (353 words)
Propeller Solutions, Inc. is a technology-based company specializing in custom performing propellers for pleasure yachts, sport-fishing vessels, high-speed vessels, and for those concerned with smoothness, efficiency, and performance.
Propeller Solutions is called on by Naval Architects, Builders, Owners, and Captains for assistance in the design process with problem-solving or for performance and efficiency solutions.
Our propeller designs range from a flat face constant pitch for slow to medium speeds, to a cambered, skewed design with a variable pitch distribution for high load conditions and maximum performance.
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