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<< Lancair Builders' Mail List >>
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> <<Second, he claimed that there would be about an 8% speed increase because
> the engine would run cooler, smoother, and freer with the same
> configuration. Since your configuration has not changed, it would appear
> that the speed claim is not valid. Any thoughts on this issue would be
> appreciated.
>
> Harry League>>
Here is mine. An 8% increase in speed requires about a 25% increase in power
coming out of the prop. About 80% of the energy produced by the fuel burned either
goes out the tail pipe or produces useful work at the prop. If you eliminated ALL
of the cooling and friction losses you would still be short of the mark.
The only other way to go faster is to reduce drag and cooling drag, the drag of
the air going through the engine, is estimated to be around 1/2 of the total drag
in our slippery airplanes. It is difficult to say how much drag is attributable to
heat flux into the coolant stream but it is theoretically possible to reduce drag
by ADDING heat to the cooling flow.
Regarding anti friction coatings on bearings, I find it interesting that all the
claims infer that the bearing and shaft actually touch. In reality, the shaft in a
plain bearing is supported by a thin film of engine oil. The shaft and bearing
only come into direct contact if the engine has not been running for a while or if
the bearing is highly overloaded. Most engines will run at idle speeds without
load for several hours without oil pressure, even if they don't have voodoo
coatings or additives. The primary function of oil flow through a bearing is
cooling. Supply oil pressure has no effect on a bearings ability to support a
load.
Regarding ceramic coatings, yes they work, BUT they are quite fragile and prone to
flake off. We ran ceramic coated rotors in the engine of an GTU Mazda RX7 in
qualifying at the 24 hours of Daytona to capture the pole position. We did not run
the coated engine during the race because of our experience with spalling and
ablation of the coating. Turbochargers do not appreciate ingesting chunks of
ceramic.
The one pure truth in all of this is that it seems that gullible customers are
easier to find than certifiable test results.
Regards
Brent
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