How to figure best glide speed? - A simple rule of thumb

[Dan T]

If you look at the polars for any glider you will notice that the glide
ratios are fairly flat near the slow end of the glider's performance curve and will
drop off steeply at some point above typical trim speed. What this means is
that if you err on the slow side of best glide you will have given up very
little in any circumstance other than a race. If you err on the fast side you
are much more likely to put yourself on the ground earlier than you need to.

For most pilots flying slow in most conditions and somewhat faster in
significant sink will serve you well.

Dan T

[Danny Brotto]

Not sure I follow you here Dan. If by the "flatter portion of the polar" you mean the speeds between min sink and a few miles over max L/D, unless you "must" minimize my sink rate (i.e. boat around or get through an extended sink cycle w/ little chance of finding another source of lift), I vote to fly on the faster side of max L/D. A couple of reasons; generally flying faster than max/ LD will get you to the next thermal/lift source more efficiently (i.e. higher when topping out/time spent.) Also, when you get to that next thermal/lift source, you'll have a bit more energy for maneuvering.

In thermic conditions or gusty conditions, flying on the slow side will create stall conditions where the sink rate drops of precipitously. Definitely carry a bit more speed in textured air.

Oh yeah, flying fast is more fun anyway.

Danny Brotto

[Flying Lobster]

Speeds to fly for an Eagle? That's easy.

1.Most of the time, don't pull in too much when flying into the wind.
2. Best speed to fly is fall over the back in a tailwind.

marc