Tim Ward wrote:


I found this laser sensor on the web:
http://www.navysbir.brtrc.com/succes...navsea_p3.html
Not many details.
Assuming it's accurate enough, one could be used to get the glider's
vertical speed through the airmass.
Now you have both horizontal and vertical velocity measurements relative to
the local airmass.
That should simplify the problem.

A Google search turned up laser airspeed sensors that, in concept, could
be used to measure L/D directly from the glider. Some of them were good
for the low speeds we need to measure sink rates. So, have one pointing
forward, one pointing down, divide the forward speed by the sink rate,
and ta-da! L/D. It wouldn't matter what the airmass was doing, since the
measurements are relative to the airmass.

Unfortunately, none of the units I saw seemed to be small, cheap, or
readily available, as their audience appeared to be military types or
rather expensive aircraft.


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Eric Greenwell
Washington State
USA