To obtain increased dependability, ef-ficiency from the engine, to help in avoiding engine failure, to provide adequate informa-tion, all accessories necessary for function-ing, a device for propelling an aircraft, an engine-driven shaft, a plane of rotation, de-signed for abinitio training,
to convert the straight-line motion of the pis-ton to the rotary motion of the crankshaft, to ignite the fuel, to complete one cycle, expansion of the burning gas, the remaining heat, through openings in front of the engine cowl, under all operating conditions, within the tolerable limits.
Reading for developing language intuition
Ex. 42. A: Read Text “Engine” without using a dictionary and guess the meaning.
B: Read the text again and make your own list of unknown words.
C: Read the text for the third time to see if you can guess the meaning of the sentence without misunderstanding the unknown words.
D: Compare your word list with the classmate to help you understand the text.
Text ENGINE
Knowledge of a few general principles of engine operation will help the pilot obtain increased dependability and efficiency from the engine and, in many instances, this know-ledge will help in avoiding engine failure. As different types of aircraft are equipped with different types of engines, it is impractical to discuss in detail the various types of engines here. Information from the manufacturer's instruction manual; familiarity with the oper-ating limitations for the airplane
engine; and specific advice from a flight instruc-tor should provide adequate information to op-erate an airplane engine satisfactorily. Aircraft engine is an engine that is used or intended to be used for propelling aircraft. The aircraft en-gine includes all accessories necessary for its functioning, but does not include propellers.
Propeller is a device for propelling an aircraft that has blades on an engine-driven shaft
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Aviation English Fundamentals | 30
and that, when rotated, produces by its ac-tion on the air, a thrust approximately per-pendicular to its plane of rotation.
Most light airplane engines installed on aircraft designed for ab-initio training are in-ternal combustion of the reciprocating type. They are called reciprocating engines because certain parts move back and forth in contrast to a circular motion such as a turbine. The re-ciprocating engine consists of cylinders, pis-tons, connecting rods, and a crankshaft. One end of a connecting rod is attached to a piston and the other end to the crankshaft. This con-verts the straight-line motion of the piston to the rotary motion of the crankshaft, which turns the propeller. At the closed end of the cylinder there are normally two spark plugs which ignite the fuel, and two openings over which valves open and close. One valve (the in-take valve) when open admits the mixture of fuel and air, and the other (the exhaust valve) when open permits the burned gases to escape. For the engine to complete one cycle, the pis-ton must complete four strokes. This requires two revolutions of the crankshaft. The four strokes are the intake, compression, power, and exhaust. The following describes one cycle of engine operation.
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As the piston moves away from the cy-linder head, the intake valve is opened and the fuel/air mixture is drawn into the cylind-er. This is the intake stroke.
As the piston returns to the top of the cylinder, both valves are closed, and the fuel/air mixture is compressed. This is the com-pression stroke.
When the piston is approximately at the top of the cylinder head, a spark from the plugs ignites the mixture, which burns at a controlled rate. Expansion of the burning gas exerts pres-sure on the piston, forcing it downward. This is the power stroke.
Before the piston completes the power stroke the exhaust valve starts to open, and the burned gases are forced out as the piston returns to the top of the cylinder. This is the exhaust stroke.
A spark to ignite the fuel/air mixture in the cylinder is provided by the ignition system.
The burning fuel within the cylinders pro-duces intense heat, most of which is expelled through the exhaust. Much of the remaining heat, however, must be removed by the cooling system to prevent the engine from overheating
Most light airplane engines are air cooled. The cooling process is accomplished by cool air being forced into the engine compartment through openings in front of the engine cowl.
The oil system is used as for storing and circulating oil throughout the internal compo-nents of the engine. The oil temperature gauge indicates the temperature of the oil which is heated by the engine.
The fuel system is intended to conti-nuously supply fuel to the engines, meeting the engine demands under all operating conditions and maintaining the center of gravity position within the tolerable limits.