On Thu, 20 Dec 2012 05:34:12 -0800, Bastoune wrote:

I have a LX V7 variothat has that functionality. The
automatic switching of the STF is currently based on a GPS input
(straight flight = STF, turn = vario). I am moderatly happy with the
automating switching based on that logic. Is there a better one? I
understand that the vario could also switch to SFT above a certain speed
(e.g. 60kts) but I find myself flying at best L/D at times. In that
case, the vario would automatically revert to "Vario". What "automatic
switching logic" works best in your experience?

I have an SDI C4 vario that offers the choice of manual, speed and turn
switching. The older C3 allowed you to choose speed or turn and override
it (the manual switch had a three position switch: climb-auto-cruise but
the C4 omitted the manual override. I tried circling and hated it and now
use speed switching. This instrument allows different speeds to be set
for cruise-climb and climb-cruise which is useful: I like climb-cruise
set 5-6 kts faster than cruise-climb and would probably hate a vario
that had only one switching speed, but ymmv.

If you try speed switching, be prepared to spend time tuning it to the
way you like to fly the glider its in: using the same instrument in two
fairly different gliders showed me that you need to tweak both the
switching speeds to suit both the glider and your flying style, but get
it set right and it is almost always in the mode you want.

A reasonable start point is with cruise-climb set about 2-3 kts below
best glide speed and climb-cruise set around 5 kts above best glide.
Then go fly and adjust as needed. What you want is for it to stay in
cruise along a weakish street but not suddenly jump out of climb while
you're thermalling.



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martin@ | Martin Gregorie
gregorie. | Essex, UK
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