On Jun 1, 2:01*pm, John Cochrane
wrote:
Agree, but he seemed very sure that he had been told by his instrument
designer that MC zero would alway yield max range glide since the
computer knew the wind and would take account of it.

Maybe I should ask Dave directly since the SN10 was the instrument in
question.

Andy

I pity our poor instrument designers. If they do nothing, mad pilots
will write in "something's wrong with your instrument, as I lower Mc
setting it shows me a worse glide angle!" If they make Mc=0 always the
glide extending setting, mad pilots write in with "something's wrong,
I select Mc 0 and it's telling me to fly 70 knots." If they set a
sticky knob that won't go below the glide-maximizing Mc value, mad
pilots will write with "something's wrong, I can't lower the Mc
setting."

John Cochrane

While I am not arguing against the theory behind MC settings I would
like to add couple of points which I am sure most of you are aware
anyway:
1 - Using lower than calculated MC setting will hurt your speed much
less than taking a wrong turn or wrong line, so don't get too anal
about it.
2 - The theory does not take into account the terrain ahead, ground
clearance, the probability to find another good thermal, the risk of
getting out of glide of landable strips, the significant increased
risk of landout, and your comfort level when getting low which will
often translate (for most of us) in more time spending circling in
weak lift and even unecessary deviations.

For what it worth, my MC setting is usually between 0-3, regardless of
wind.

Ramy