On 20 Oct 2003 22:53:12 -0700, (Adnan H. Mirza)
wrote:

Hi guys,

Can either of you elaborate on how the SN 10 estimates wind speed?
I've heard that it's pretty good and fast for this. Does it have a
built in mag compass?

Thanks
You don't need a magnetic compass to get wind speed and direction.
You have GPS ground track and speed and TASat any given point. If you
do another GPS ground track/speed and TAS at a nearby point but on a
different ground track and make the assumption that the wind has not
changed you have enough information to solve the two wind triangles.
In practice you need set some traps for the odd bad result and do a
little averaging to get a sensible result but 10 seconds or so if the
GPS is coming in at 1 Hz is acceptable. This works even if you aren't
circling but are figure eighting or zig zagging which is why we call
it the zig zag wind in the B2000. You get a good wind estimate in half
a circle or so when thermalling.

You can always get a wind component in the direction you are going by
doing a difference between the TAS and Groundspeed. This is
essentially in real time.

You can see the B2000 manual at our website
www.borgeltinstruments.com

Mike Borgelt