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21 Cards in this Set
- Front
- Back
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What is the man advantage of horizontally opposed engine over a radial engine for powering modern aircraft? |
A smaller frontal area that is easier to streamline |
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How many throws are there in the crankshaft of a six cylinder horizontally opposed engine? |
6 |
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What kind of connecting rod arrangement is used in a radial engine? |
A master rod connects a single throw to the crankshaft with a piston. All other Pistons are connected to the master rod with link rods |
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Of what material are most piston rings made? |
Gray cast iron |
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What is the reason for using hydraulic valve lifters in an aircraft engine? |
Keeps out the Clarence between the valve operating mechanisms. And decreases the wear of the valve train component |
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At what speed does the camshaft turn, relative to the crankshaft speed in a horizontally opposed engine? |
A camshaft turns one half the speed of the crankshaft |
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What kind of main bearings are used in a horizontally opposed engine? |
Steel-backed, lead-alloy bearing inserts |
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On what stroke is the piston of a reciprocating engine when intake valve begin to open? |
On the exhaust stroke |
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On what stroke is the Piston of a reciprocating engine when the exhaust valve begins to open? |
On the power stroke |
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Why are both the hot and cold valve clearance given for most radial engines? |
For valve timing purposes, the cylinder number one is set at the hot valve clearance and once set all other cylinders are adjusted to their cold clearance |
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What is meant by a cam-ground piston? |
Piston that is not perfectly round in it's dimension parallel with the wrist pin, once it becomes heated due to the temperature changes it expands enough that it becomes perfectly rounded |
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Where is the piston in a reciprocating engine when the ignition spark occurs? |
About 30° before the piston reaches top center on the compression stroke |
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What is meant by a full-floating wrist pin? |
A wrist pin that is not clamped to either the Piston or the connecting rod, usually protected by metal plugs in their ends, to prevent scoring of the cylinder walls |
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Why do most aircraft reciprocating engines use more than one spring on each valve? |
To minimize valve float. The springs have different resonant frequencies so one spring will always be exerting a force on the valve |
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Would excessive valve clearance cause the valves to open early or late? |
Late and close early |
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What is the purpose of a valve clearance in a reciprocating engine? |
Allows the intake of induction charge or air-fuel mixture, and the exhaust gases leaving the cylinder |
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What type of piston rings are installed on the Pistons of an aircraft reciprocating engine? |
Compression rings, oil control rings, and oil wiper rings |
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Why are some exhaust valves partially filled with metallic sodium? |
It helps to cool the valve head by transferring the heat into the valve stem so it can be transferred to the cylinder head through the valve guide |
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What causes detonation in an aircraft engine? |
Excessive heat and pressure in a cylinder would cause the air- fuel mixture to reach a critical pressure and temperature that it explodes rather than burns.The explosion is called detonation |
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Why is compression check important to determining the condition of an aircraft reciprocating engine? |
The compression check can determine the condition of the seal between piston rings and the cylinder walls as well as the intake and exhaust valves and their seats |
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What is meant by the compression ratio of a reciprocating engine? |
The ratio of the volume of the cylinder with the Piston at the bottom of its stroke to the volume with the piston at the top of the stroke |
