Robert Ehrlich wrote:

Or, perhaps the laser unit could be used to determine when the airmass
is steady enough to make flight testing worthwhile, even it if can't
measure the vertical velocity sufficiently accurately to make
corrections useful.



OK, but this is far from the original question. Making Johnson-style flight
tests is one thing, using flight logs for polar analysis in another one.
A flight log provides some information about the polar as long a we have
or can assume some information about the airmass. We have here a huge
quantity of data it would be intersting to use. We could get some information
not found in flight test, like how far various gliders of the same model
are from the tested one, how performance degrades with time, ...

I think the thread drifted from the original question because no one
could think of how to account for the airmass movement in any useful
way, so people began thinking of what the next best thing might be. A
new proposal on how to achieve a polar from flight logs would bring the
thread back to the original subject, I think.

Here's another way that flight logs might used: Comparison flights using
GPS logs to determine the difference between gliders would be useful,
but that requires at least two gliders to fly together at the same
airspeed; again, useful, but as you point out, not an answer to the
original question.


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Eric Greenwell
Washington State
USA