XCSoar and Wind

I can confirm it takes a few circles before there is enough data for wind calculation. In a glider you usually won't notice since the first thermal will provide plenty of circles.

Thanks Guys,

This is a touring motor glider and, this time of year, there isn't much
thermalling. I'll live with it until spring.

On 11/21/2015 5:45 AM, Alex wrote:
I can confirm it takes a few circles before there is enough data for wind calculation. In a glider you usually won't notice since the first thermal will provide plenty of circles.

--
Dan, 5J

Looks like Dave had the right answer.

I flew the motor glider today and took some time to circle in reduced
sink (there was no lift) and, after 4 or 5 turns, voila! I had a wind
arrow, direction, and velocity.

On 11/20/2015 3:18 PM, Dave Leonard wrote:
Hey Dan,

After poking around through the code, it looks like if you need a couple things to get GPS only winds:
1) Average GPS update rate of 2 sec between updates over the duration of the circle. So dropouts during the circle could disqualify it from the calculation.

2) And the time to complete the 360 turn needs to be less than 50 samples. Not sure, but I think the Streak has a nominal 1 second update rate.

The quality of the wind estimate improves with more turns and with more constant airspeed control. I'm not sure if circling detection has to occur before wind calculation can start, but you probably need a couple good relatively tight turns to make it compute the winds.

It is open source, so you can change it if you're willing to dig into it.

Dave, ZL


On Friday, November 20, 2015 at 9:07:02 AM UTC-7, Dan Marotta wrote:
Thanks, I haven't done that many turns since trying this out. Next
time...




On 11/20/2015 8:56 AM, Guy Corbett
wrote:



If you have no airspeed information the only way to calculate the wind is
by measuring the drift of your circle in circling mode. In my experience
XCSOAR wants 4-5 thermalling turns before it calculates the wind.

At 15:27 20 November 2015, Dan Marotta wrote:


Apparently my question is not understood by the developers or XCSoar
does not independently calculate and display wind.

I do not want to manually enter wind based upon a guess of what it is.
I want XCSoar, running on a Dell Streak 5, with no external device
connected, to calculate and display the wind.

Does XCSoar do that? How to I make it do that? I have tried all of the
suggestions and, without an external source, i.e., CAI-302/Bluetooth, I
get no wind.

On 11/20/2015 12:45 AM, Surge wrote:


On Thursday, 19 November 2015 23:01:48 UTC+2,



wrote:




OK, more speculation about how this works. Looking at the code.

In =6.8, if wind is set to Manual (not Auto), and External wind is



present then External is used. If you then set wind manually, that
overrides the External wind.



In the Modal, once you select wind manually, a "Clear" button appears



(it is not there before). Select 'Clear' once you are done with the


Manual


wind and it goes back to using External (if present).



Hope that's how it is.

David


I asked that question yesterday on the XCSoar forums and Max (one of



the


main developers) replied.


Question:
Is the Manual option the same as disabled if an external wind source is


available?


Max's answer:
Yes. Good commit message, but bad naming in user interface.


--
Dan, 5J








--

Dan, 5J

--
Dan, 5J

I tried this few times in couple of flights recently. Unfortunately looks like it is no longer possible to enter manual wind in XCSoar if you using external source like 302. I tried entering values manually in manual mode (as well as circling etc) and it immediately switched back to the external value. No matter what I tried, it continues showing external wind. I suspect this is a bug and not intentional as it was possible to enter manual wind in previous versions, crucial when you on final glide into different airmass but the wind remains the last calculated value.

Ramy

Ramy,

I use LK8000 V5 and even though it can receive my SN10B winds, I always configure the winds manually. SN10B winds are more accurate... but far less accurate than the Butterfly IMU based system (AirGlide) according to reports from a few friends.

Circling winds from LK8000 are similar to the SN10B's, but like you... I prefer to set winds manually which is on my checklist before taking off.

Walt Rogers WX

Considering wind changes with altitude and geographical location you must have a data entry clerk on board to keep it accurate.