On Saturday, 18 May 2013 02:33:22 UTC+3, Eric Greenwell wrote:
krasw wrote, On 5/17/2013 10:33 AM:

(and as a side produt most accurate speed-to-fly commands I've seen).

In this respect Butterfly Variometer is not comparable with other

current systems. I think this fundamental difference is not

completely understood here.



I really curious about what an "accurate" speed-to-fly command is. What

is the command based on that makes it more accurate than the usual

variometer, like a 302?



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm

http://tinyurl.com/yb3xywl

Speed-to-fly is essentially function of vertical airmass movement. When you get inertial-based netto, which is very fast and accurate, your speed-of-command accuracy goes up order of magnitude. With normal TE-based speed-to-fly you normally try to filter out gusts with longer time constant. With inertial netto this gust-induced noise transforms into data that you can use for calculating optimum STF.

With Butterfly I have actually started experimenting with extremely short time constant for inertial netto. It can be set so short that netto becames essentially a quantitative indicator of your seat-of-the-pants feeling. There seems to be no reason to filter or average this data so heavily.

krasw