The Engine

The word engine originally meant any ingenious device,and came from the word ingenious, clever. Any kind of vehicle must be able tomove. The ability demandspower. A machine that produces mechanical power or energy isan engine or a power plant.

Engines presentone of the most interesting groups of problems consideredin the engineering field. One of the main problems is receiving the maximum possible power or thrustfor minimum weight. The weight is included in the factor called the weight/power ratio, which may be definedas the weight in pounds per horse power output.

Another important problem is that of fuel. Both in the past and today the designers work at the problem of getting lower specific fuel consumption.Specific fuel consumption is obtained by dividing the weight of the fuel burned per hour by the horse power developed.

Another possible problem considered in any engine is its flexibility.Flexibility is the ability of the engine to run smoothlyand perform properly at all speeds and through all variations of atmospheric conditions.

One more important problem worked atby the designers is the engine reliability. The engine is to have a long life, with maximum of time between overhaul periods? In some cases the problem of balanceis one of the main. Balance has several possible meanings but the principle factor is freedom from vibration. Besides any engine must be started easily and carry its full loadin a few minutes. There are gasoline engines, diesel engines, gas turbines, steam engines, jet engines and rocket engines. Each of them has certain advantagesand disadvantagesover other forms of power plants.