On Wednesday, October 21, 2015 at 7:01:38 AM UTC-7, Dan Marotta wrote:
Of what use is instantaneous wind?* Can you react to it without
flapping control surfaces all over the place?* Do you use it for
planning your next turn in a thermal?



Not knocking it, I just don't get it why it would be important.*
Please enlighten me.




On 10/21/2015 3:06 AM, krasw wrote:



On Wednesday, 21 October 2015 03:32:11 UTC+3, jfitch wrote:


Regarding the description of wind accuracy in the first link: This was my impression also: that the instantaneous wind indication could not be accurate, as it was so dynamic. However after two years of use I have come to believe it is accurate, and the wind field really is that dynamic, you just had no way to measure it before. This instrument is really in a class of its own.


I agree, I started noticing noise in wind measurement when going to under 2 sec time constant. Wind measurement is basically as fast as the variometer. Now who would do a software where I could record 3D airmass movement with AIR Glide to a file and visualize it later with Seeyou or similar?





--

Dan, 5J

The companion software iGlide uses it as a thermal centering tool. Each lift dot displayed each second while thermaling has in it an instantaneous wind vector. These point towards the center of the thermal with pretty good reliability. I have experimented with using the instantaneous wind deviation to judge which way to turn, however iGlide does not display the vectors until you have already turned about 270 or you zoom in to an otherwise unusable level. Something I would like them to work on.

There are other uses: flying out of Truckee and returning from the south we have long known that the glide over the Carson valley is usually better than fair at the end of the day. I thought this was due to delayed sink, buoyant air, or something. But now I know that there is very frequently a strong tailwind blowing up the middle of the valley above about 12,000 ft. Like 22 - 28 knots from the south on an otherwise 10 knots from the west day. So rather than crossing directly to Lake Tahoe, I now fly up the middle of the valley until I lose that tailwind, then turn. Never knew that before and most people still don't. This kind of tailwind will eventually show up on computers using traditional wind calculation methods, but the time constants are so long you will lose most of the benefit. The shift in velocity does not show up on CU or XCSoar until you are just about out of it.

I also now notice serious wind shears with increasing altitude. The headwind may increase from 12 knots to 22 knots in 500 ft of climb. Usually near the top of the thermal band, but worth exploiting in some instances.