On Wednesday, October 29, 2014 11:23:02 AM UTC-7, wrote:
On Wednesday, October 29, 2014 11:00:05 AM UTC-7, Jim White wrote:
All very interesting but I would bet that Seb Kawa could beat us all with
just a simple winter vario.

He most likely would, and easily. But he still loves his Butterfly vario. Below is a quote from an interview with him, about his observations during the EGC in Vinon. The value of the inertially derived real-time vector wind is just beginning to be understood because it is so new. It sheds light into the microstructure of the airmass. I most definitely will be installing something like this in my next glider.

David

Source: https://www.facebook.com/air.avionic...46343178758534

".. it helped very much and not only in wave. The indication changed very quick and you could get extra information about convergencies, and wave spots in the way it was not possible before. Example - flying near the thermal I was able to notice that the wind was changing towards the thermal. In the thermal wind was still. After such experience I was turning according to the updated wind dirrection and it proved that the lift was in that direction.
I could see the sudden wind change when passing Col de Var - it has changed rapidly to 45km/h , so I new in few seconds where to look for the hill lifts.
Following big convergence line I used the wind indication, taking into account that wind was blowing towards the lift line.
In the wave - we had weak wave. In the day when it was strong, my class did not fly. But - it is easy to see that wind is slowing down in lift area..."

In fact if you use iGlide, the thermal assistant makes use of this fact: each second a lift dot is placed on your track. In each lift dot there is a wind vector. In well organized thermals all of the wind vectors all around the circle point towards the center. In less well organized thermals it isn't as clear, but still you can draw some conclusions. The lift is most likely strongest where the wind is still, and vectors pointing towards the still area give you an idea of where to correct to.

The wind is surprisingly dynamic around thermals, at least as reported by the Butterfly. It is quite common (as Kawa says) to have the wind deflected towards the thermal, and still inside the thermal. Think what that means when flying directly through a thermal co first there is an increasing tailwind component which will feel like a downward acceleration. As you enter the core the tailwind decreases to zero, then becomes a headwind as you exit the other side. To the glider, that all looks like a horizontal gust from ahead (in addition to whatever the vertical component is), with the associated accelerations and other changes. I believe that is one of the reasons that lift very often seems softer, once centered, than you thought you experienced on your first pass through. Part of it is a phantom of the wind gradient.

This last season I started using this: you enter what you think is lift but there is no clear indication of which way to turn. Looking at the instantaneous wind, turn towards it (or more properly towards its deviation). More often than not, that is the correct direction.