On Tuesday, October 28, 2014 5:24:58 PM UTC-7, jfitch wrote:
On Tuesday, October 28, 2014 5:07:05 PM UTC-7, Mike the Strike wrote:
The issue with horizontal gusts is that if you fly into a thermal outflow (quite common where they are strong and dry), it temporarily increases your airspeed. The TE probe outputs a signal that interprets this increase in aircraft energy as lift. There is no acceleration, just an increase in energy. The seat of your pants may well be able to sense the lack of acceleration in this circumstance, but sensitive accelerometers will be even better.

Mike

The Butterfly vario calculates wind, purely inertially derived from accelerometers, about 20 times a second. If you believe it (and I do mostly, based on independent checks) you learn that the wind it quite dynamic around thermals. 10 or even 15 knot changes in and around western desert thermals are common. This messes with both your backside and your compensated vario. There appear also to be pressure gradients in and around thermals, which confuses things further for barometric based varios.

John,

You can also set the wind filters to a faster number as low as 1 sec. I have mine set a 10 sec.

Richard
www.craggyaero.com