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Old September 19th 16, 02:16 AM posted to rec.aviation.soaring
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Default AA Butterfly versus CNv LCD wind calculation

On Sunday, September 18, 2016 at 5:24:31 PM UTC-4, Tango Eight wrote:
On Friday, September 16, 2016 at 4:23:48 PM UTC-4, wrote:

Does the CNv (with latest 3.3.3899 or beta 3.4.4089) calculate wind as quickly as the Butterfly?


No.

T8, what is the wind direction update rate of the CNv?


I don't have a quantitative answer here. Mostly it depends on your flight path. CNv depends on some GPS track variation for vector wind calculation, but it doesn't take a great deal (20 degrees total track seems to do it in most cases). Given sufficient GPS track variation, the fast wind seems to update in just a few seconds ( 10). The auto wind is slower, gives a more stable number. It seems to take a few tens of seconds to update. Either mode is noticeably faster than previous generation flight computers (302, SN-10B). I haven't flown the Butterfly vario. The component head/tail wind is updated very fast (less than a second).

The only difference between "auto" and "fast" winds in CNvXC is the time constant. I see no downside to the fast wind, so I've been lobbying to make this the default. The fast wind is excellent for close in mountain flying.

best,
Evan / T8


Thanks T8.