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Old April 12th 07, 12:21 PM posted to rec.aviation.soaring
Andy[_1_]
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Default Takeoff distances

On Apr 11, 5:38 pm, "Kilo Charlie" wrote:
I am a bit surprised at the lack of opinions re this so far. It is data
that we should be able to generate and definitely would be helpful to those
of us flying out of hot high airports.


If you had data you would need to careful in its interpretation.
Glider launches usually take place when thermal activity has started.
Wind shear and thermal downdrafts can be expected and, singly or in
combination, and they can easily reduce climb rate to zero or make it
negative.

Let's say the data show you only need 1000 foot of the 5000ft runway
and the predicted climb rate is 200fpm for the first 500ft, and the
predicted thermal strength is 6kts, and the wind is gusty. Would you
launch? I suspect the answer would be yes. We do it all the time and
usually it works out ok.

Since I know what prompted the question I'll comment that Williams has
similar conditions to Flagstaff. That airport has a poor record for
summer takeoff accidents and that's for airplanes without a glider in
tow. Usually it works out ok though.

Andy