Re: unpowered glide ratios

From:         Phil Fernandez <philf@xymox.palo-alto.ca.us>
Organization: Jade and Jett Incorporated
Date:         14 Oct 94 02:23:34 
References:   1 2
Followups:    1
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In article <airliners.1994.1593@ohare.Chicago.COM> drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard) writes:
>Just in general, one can assume a glide ratio in excess of 20 to 1.
>The 737 is around 22 to 1, depending on the exact model and configuration.
>This is assuming the engines are at idle, or at least windmilling.  It does
>get worse if they are not turning at all.

Is this really accurate that windmilling turbines/fans *increase* the
glide ratio on a jet, and get worse if they aren't turning.  This is
the exact opposite of the result on a prop, where an upowered
windmilling prop has near the same drag as a disk of the same
diameter.  On a prop plane, a stopped prop definitely increasess the
glide ratio.  What's the scoop?

pmf
pp-asmel-ia
mooney n5632j