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Difference between revisions of "Common Questions and Answers"
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Common Questions and Answers (view source)
Revision as of 00:40, 13 April 2022
, 00:40, 13 April 2022→Why do radial engines leak oil?: Add Additional Explanation of Hydrolock
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The cylinders in a radial engine are arranged in a circle around the crankshaft, so the cylinders on the bottom of the engine are upside down. Over time gravity causes the oil to drain from the upper cylinders down to the lower ones, where it collects. Since the cylinders on the bottom are upside down, and the valves and seals are not designed to contain it, the oil leaks out around them. | The cylinders in a radial engine are arranged in a circle around the crankshaft, so the cylinders on the bottom of the engine are upside down. Over time gravity causes the oil to drain from the upper cylinders down to the lower ones, where it collects. Since the cylinders on the bottom are upside down, and the valves and seals are not designed to contain it, the oil leaks out around them. | ||
This is | If enough oil pools in the lower cylinders, it can result in a condition called “hydrolock”.{{efn|The “hydro” in “hydrolock” does not refer to water. It is a shortened form of “hydraulic” or “hydrostatic”.}} Hydrolock occurs when a fluid, such as oil, builds up in the combustion chamber of a cylinder. Since the fluid is nearly incompressible, the piston cannot complete its full stroke. Depending on the amount of force applied, attempting to turn the engine over will either be impossible or result in damage. | ||
This is the reason that propellers on aircraft with radial engines are “pulled through” before a flight.{{efn|For a good example of this, see a video by the Champaign Aviation Museum.}} Doing so allows the crew to check whether hydrolock has set in. Alternatively, it may be performed as a preventative measure on aircraft that have not been run in a while to recirculate the oil throughout the engine.{{efn|Once hydrolock has occurred, pulling the propeller through is impossible. It only serves to prevent it from happening or discover if it has set in, not solve it once it has occurred.<ref>{{cite web |last1=Durden |first1=Rick |title=The Pilot’s Lounge #27: Radial Engines and Hydraulic Lock |url=http://www.avweb.com/features/the-pilots-lounge-27radial-engines-and-hydraulic-lock |website=AVWeb |access-date=13 April 2022 |date=9 October 2000}}</ref>}} | |||
=== Why do some aircraft have folding wings? === | === Why do some aircraft have folding wings? === | ||