![workdone by engine vs heat exhausted workdone by engine vs heat exhausted](http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/heaengcyc.png)
We reviewed six years’ worth of NTSB accident data, culling the engine failure accidents. But to avoid doing the stupid stuff, you have to know what the stupid stuff is and that’s what we’re covering here. And considering that up to half of all engine failures are avoidable human-induced calamities, the risk could be even lower than that. In 2016-the most recent year for which we have complete data- engine-related accidents amounted to 0.21 accidents per 100,000 flight hours, which is about 25 times lower than the overall accident rate.
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Let’s put the standard risk metric on it. Mechanical failure persistently accounts for about 15 percent of all crashes in general aviation, but not all mechanicals are engine related. Hammer hitting nail heats it.So are they reliable? Well, yes, if you let them be by slaking them with gas and oil, following the procedures written right down there in the POH and avoiding the maintenance blunders that cause a surprising number of engines to fail in flight.Dropped cup breaks pieces do not spontaneously reassemble themselves.Molecules do not migrate to one corner of room.Change in entropy S of a system when heat Q is added to it is DS = Q/T According to Second Law of Thermodynamics, the entropy of an isolated system never decreases.Heat engine operated in reverse CP = Q2/W = Q2/(Q1-Q2) Coefficient of performance W is work done by motor/compressor Q: Will your kitchen be hotter or colder with the refrigerator door open?.Many other engine designs exist such as Sterling engine.Gasoline engines operate at 15-25% efficiency.An ideal engine operates between 900 and 500 degrees.In one cycle of an engine 5000 j are released by burning and 3000 j are exhausted.Eff ideal = 1 – TL/TH for Carnot Engine.QH = W + QL QH is at operating temperature.
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