I walked out of the terminal at Quartz Mountain Airport on Saturday. A
northerly breeze was blowing perhaps 7 mph down the runway. I went to
walk past the waist high stand parallel to the runway where pairs of
wooden wheel-chocks are stored, and of the ten pairs, there was one pair
swinging East-West in the Northerly breeze.
I knew that nobody had just hung them up so I stopped and watched.The
chocks are 12 inches long, with a cross-section of a right triangle of
two equal sides and an hypotenuse measuring about five inches. A pair
is joined by 2 ft of 1/2 inch rope tied at a hole perforated at one
acute apex end of each of them.
And I saw what was happening. Though chocks on either side were steady,
this pair touched near their ends, and as the nearer chock swung away at
an angle of perhaps 130 degrees to the breeze, at the limit, it pivoted
so that its trailing edge, now leading edge made an angle of perhaps 80
degrees to the wind, and that was enough. Now I had learned the
trick, I set another pair with a long face at 130 degrees to the wind
and had it pivoting on its partner too.
An object lesson on the flutter encouraged by too much mass after the
hinge point.