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Old December 14th 09, 08:53 PM posted to rec.aviation.soaring
Papa3
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Default Optimum CG Range

On Dec 14, 8:56*am, wrote:
On Dec 13, 9:19*am, JJ Sinclair wrote:


Another useful approach is start at about 66% aft using manufacturer's
CG range. When making the tightest turn you normally do, if you run
out of elevator, you need to shift CG back a bit. You will probably
end up around 75%.There isn't a huge benefit in having the CG way
back, but there is a significant deterioration of handling which
requires better pilot skills to offset.The last little bit of glider
performance costs quite a bit in pilot workload until you are very
proficient. I usually take a couple pounds out of the tail in the
Spring and put it back in when my skills are back up to snuff.
FWIW
UH- Hide quoted text -


Also FWIW and purely as a first approximation, I've noted that the
following works reasonably well in most glass birds I've flown.

- At altitude, trim the glider so that it flys at "about" best L/D
airspeed. This is usually somewhere between 50-55kts.
- If that trim position results in significant up-elevator, you need
more weight in the tail. "Significant" in this context means that you
have more than a small percentage of the available up-elevator travel
dialed in to maintain best L/D airspeed.

Obviously, this is only a secondary check after you've already run the
numbers or done a proper W&B, but it seems to work pretty well. In
my LS8, the above works out to about 80% of manufacturer's aft limit
and results in very pleasant handling and obvious improvement in get-
home performance on weak days.

Anything wrong with this approach?

P3