On Thursday, February 14, 2013 3:19:21 PM UTC-7, Kimmo Hytoenen wrote:
After Argentina some competition pilots were quite disappointed

with the new variometers using acceleration to calculate lift. I

have not tested myself, just telling their opinion.



At 21:49 14 February 2013, John Galloway wrote:


If the butterfly -- or clearnav, with future software -- did

read

out 3 d

w=

ind 20 times a second, this would be a big advantage. Not

only could you

de=

tect lift long before F =3D MA gets the glider moving upward,

you could

tel=

l upward gusts from forward gusts and sideways gusts.

Dynamic soaring

might=

even become possible, or at least better energy extraction

from gusts.

Eve=

n the 302 has the necessary sensors, my impression is that

we're all

waitin=

g on the software development.=20



John Cochrane



Regarding gusts, the Butterfly website (in FAQ) already claims:



"A conventional variometer uses changes in air pressure (TE-

pressure, static- and total-pressure) to determine energy

changes the aircraft experiences. Butterfly Vario does the

same.

Additionally it uses an inertial sensing platform that allows for

real-time determination of airmass-movement and realtime

determination of wind. With this technology a pilot can judge

the difference between gust induced energy changes and

thermal induced energy changes."



John Galloway





Not sure, but I suspect they are mixing frames of reference. In theory, the way to do this is solve the TE equations in the inertial and air-data domains separately then compare them. A gust will show up strongly in the air-data but less so in the inertial data so a computer - or a pilot - can tell the difference.

A purely inertial vario will require a full IMU with GPS updating. These things are probably still too expensive for sailplanes but only just.