Anybody running a Butterfly Vario with XCSoar?

On Thursday, July 18, 2013 6:10:05 AM UTC-7, jjbird wrote:
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is it possible to describe in layman's terms how the vector is derived from straight flight observations? Component velocity obviously, but the vector?





Oops, forgot a bit...you are right that you can't get the wind vector from straight-line observation (at least with the current formulation, with more sensors you can do it). This will only allow you to predict the wind along the direction you are currently flying. As soon as you turn at all however, you'll have information about the wind in another direction. After a bit or circling or even just some turns back and forth the filter will be able to figure things out. If you fly for a long time in one direction the wind estimate might start to drift a bit though.

OK, I agree that wind velocity component in the direction of flight is derivable this way. Must the be engineer in me, "vector" means velocity and direction. My rather limited understanding of the EKF suggests that it is a very elegant way to get a quick reading for velocity out of the jittery GPS data.

On XCSoar then, if I check Both in the wind preferences and turn off the "prefer external" then I will get the XCSoar calculation based on circling or EKF filtered straight flight data? I am interested in comparing this with the Butterfly inertial derived wind vector.

Could ask this on the XCSoar forum, but for some reason I am banned from the site....

And thanks, Marc, for a quick resolution to this.