Windsocks - data please
Does anyone have a reference for windsocks ?
Specifically, what I want to know is;
Is there a requirement for windsocks at UK airports to all be rated so that they fly horizontal at (say) 15 Knots ?
If some airports use windsocks which fly horizontal at 15 Knots, and other airports use windsocks which fly horizontal at 20 Knots or 30 Knots, how would you know the rating of the windsock ?
If a windsock which is rated to fly horizontal at 15 Knots is flying at 45 degrees, does that mean the windspeed is 7.5 Knots ? Or does a sine or cosine function need to be applied ?
Thanks for your help.
Cheers,
Wings