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4.3 AIR SPEED (WITH OPTIONAL PITOT TUBE)
This sensor measures the glider’s air speed.
This function is available only installing the Pitot tube sensor module (optional). The tube will have to
be inserted in the specific housing hole located on the instrument’s top, and the parameter
(ADVANCED SETUP \ n. 1 PITO) have to be setted on desired value : IAS (Indicated Air Speed) or TAS
(True Air Speed) .
It is possible to set the speed’s unit of measure to km/h or mph using the parameter (MAIN SETUP \
n. 16 U-SP)
The minimum speed indication is 18 km/h.
4.3.1 SPEED TO FLY (WITH OPTIONAL PITOT TUBE)
If this parameter (ADVANCED SETUP \ n. 9 POLA) is set to “OFF”, all information
related to McCready, McCready Equivalent, and Netto Vario are not displayed on
the instrument.
Speed to Fly (STF) is the best anemometric speed to obtain the best glide ratio.
This value depends on performance of your glider as well as vertical and
horizontal airflow. In calm air, the optimum flying speed is the same as the best
glide speed (point B).
The diagram shows different values of speed to fly value related to different flight conditions
The X-axis shows horizontal speed, the Y-axis shows sink rate. With head wind
or sink conditions, the best glide speed increases. In order to find the optimum
speed to fly value in sink conditions, add the sink rate of the air to the polar of
your glider, drawing a new polar and a new tangent line from the initial point of
axes. The new tangent (point D) meets the polar at the point giving a higher
optimum flying speed VD.
To fly at the correct “Speed to fly” you have to adjust your
anemometric speed “IAS” to overlap the triangle symbol with the numeric
value of the optimal anemometric speed.
Posizione
indicatore
STF
ottimale
Speed to fly
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