On Aug 13, 2:01*pm, Eric Greenwell wrote:
I see gliders tied down in a bewildering variety of ways, all apparently
"adequate" in the owner's mind. AT one extreme I see multiple ropes,
straps, wing stands, and load spreaders, while at the other extreme it's
just a piece of light rope (barely more than clothesline) on each wing
tip. Two questions have slowly formed in my mind...

Question 1: Is there an analysis of the forces from wind on a tied down
glider, or maybe even measurements? Perhaps there is a "best practices"
document somewhere, derived from surveys of what's worked and what's
failed? I'm not looking for lists of personal preferences (I've seen
lots of those at airports and have the pictures to prove it!), but real
data and analysis.

Question 2: What is the effect on the wind forces when the glider has
wing covers on it, such as the Jaxida covers? I assume it reduces the
lift the wing can produce, but another pilot I talked to thought it
would increase the lift. Again, I'm looking for real data and analysis.

--
Eric Greenwell - Washington State, USA
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If at all possible, add a nose tie down. This limits the angle of
attack available and can be a big safety margin adder.
Good rule of thumb is at twice stall speed, wing is generating 4 times
gross weight in lift.
For 2-33's, we use 2 tiedowns on each main, a tiedown on the tips, and
a nose tiedown. Smaller ships use tips and nose.
We had a blow away due to a failed chain in 80 mph winds about 15 yr
ago. Once you have one, you realize extra tiedowns are cheap.
Heinz W had his ASH-25 off the ground in gust front and was saved by
nose tiedown.
UH