Slick wrote:
What is the rule of thumb to reduce the L/D when plotting a cross country
flight?

My experience with gliders ranging from a Ka-6e to an ASH 26 E is a
McCready setting of 4 on the glide calculator gives me a very high
probablity of making it to my selected landing place (usually an
airport). I don't set the speed-to-fly at 4, but at 2 or less, depending
on the conditions. My arrival height setting is 1000 feet agl.

In areas with poor landing possibilities, like a glide over a forest,
lake, and other unlandable areas, I'll increase the MC setting to 5,
perhaps even 6. If wave is about, it can be a real guessing game, and
I'll generally use even higher settings. A setting of 4 is about 60% of
maximum L/D.

Be sure your planning allows for the usual winds.

--
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Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"