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bottom of the vario.
A polar curve (shown in bold on the figure) is a graph of your glider’s sink rate over its
speed range.
The glider’s stall speed is shown by at point S and the glider’s max speed at point T on
the graph.
On the graph, you can also see three pairs of relative speed readings and sink rates. At
point A, you can see that the lowest sink rate achieved is at the top of the curve.
Therefore SinkA is the minimum sink rate and VA is the speed at which this is achieved.
The glide ratio is the ratio between the glider’s horizontal speed and the sink rate. To
find the best glide rate on the graph, a straight line is from the origin of the graph (point
O) to the tangent of the curve (point B). The speed to fly at to achieve the best glide (air
related) is therefore VB and the glide ratio is VB/SinkB.
On your instrument you can insert three different polars, go to (ADVANCED SETUP \ n.
9/17 PX-A/B/C) and choose which polar to use, go to (ADVANCED SETUP \ n. 8 POLA).
If this parameter (ADVANCED SETUP \ n. 8 POLA) is set to “OFF”, all information relating
to McCready, McCready Equivalent, Thermal Sniffer is not displayed on the instrument,
creating a cleaner display for users not needing this functionality.
There are three polars preloaded, (2 for hang gliders and 1 for a paraglider). To see the
three default polar curves and to calculate your own, use the Digifly Excel software
available from the Digifly web site (www.digifly.com).
We suggest that you insert your own polar curve data which best reflects the actual
performance of your glider.
5.3
SPEED TO FLY
To utilize the speed to fly functions you must have an air speed probe connected. The
optional air speed probe should be plugged in to the right hand socket on the bottom of
the vario.
If this parameter (ADVANCED SETUP \ n. 8 POLA) is set to “OFF”, all information relating
to McCready, McCready Equivalent, Thermal Sniffer is not displayed on the instrument,
creating a cleaner display for users not needing this functionality.
