On 2012/08/07 08:49, Ramy Yanetz <ryan...@yahoo.com> wrote:
> circling - wind is calculated based on circling drift.
No, this algorithm calculates the ground speed difference between two
opposite positions on the circle. That is much more accurate than the
horizontal drift.
> zigzag - wind is calculated when making heading changes of more than certain
> degrees. I believe it needs airspeed for this option.
Not exactly. This algorithm takes the difference between airspeed and
ground speed, and continuously estimates the wind from it. It can
only be accurate if you change your heading while you fly. This
algorithm used to be very bad, but was replaced completely by a new
algorithm two years ago that works extremely well. But you need
airspeed input, which makes it impossible to use for many XCSoar
users.
> If you have 302, I recommend this setting, as I found the 302 wind
> calculation to be more accurate and timely then XCSoar internal
> calculations.
If you think anything is wrong with XCSoar's wind calculations, or
think that XCSoar's wind calculations are worse than something else,
log a NMEA file ("raw logger") and write a ticket. Then we'll be able
to run our algorithms on that file, and reproduce exactly what it
showed you on your flight.
Note that the CAI302 needs to calibrate its airspeed/temperature probe
after switching on. You should switch the 302 on, let it calibrate,
and then power-cycle it before launching. Not doing that is a common
source of wind calculation errors. You can often see in the 302's
sensor menu that its IAS is way off.
Max
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