At 07:18 PM 6/12/2014, you wrote:
Mike.
Unsure how the mechanics of the colibri2 vario work. But it seems to
do a pretty good job of compensating. It may be using the gps data
to compensate for speed changes. My next glider won't have a mech
vario as a backup. Between a good vario with backup power and the C2
as a get me home style vario
Unfortunately that doesn't work if there is any wind.
The compensation signal is V x dV/dt where V is TAS. dV/dt is rate
of change of TAS.
If you are circling at 50 knots in a 20 knot wind the V bit will go
from 30 knots to 70 knots if you use the GPS.
Sure once you get "the wind" (in a convective atmosphere this gets
difficult to define in the shorter term)by doing a couple of circles
you can refine this but the dV/dt bit is very sensitive to errors in
the wind calculation. As with the horizontal gust sensitivity it is
the dV/dt term that causes the problem in the first place.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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