AIR_Manual_506a_ENG_rev_1.pdf
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4.3
AIRSPEED (WITH OPTIONAL PITOT TUBE)
This sensor measures the glider’s airspeed.
This function is available only with 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 has to be set on the desired value: IAS (Indicated Airspeed) or TAS (True
Airspeed).
It is possible to set the speed’s unit of measure to km/h or mph using the parameter MAIN SETUP \
n. 14 U-SP
The minimum speed indication is 18 km/h
,
11 mph.
4.3.1
SPEED TO FLY (WITH OPTIONAL PITOT TUBE)
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 related to different flight conditions
The X-axis shows horizontal speed; the Y-axis shows sink rate. With headwind or sink conditions, the best glide
speed increases. In order to find the optimum speed to fly value in sink conditions, the sink rate of the air is
added 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 “STF”, adjust your flying speed “IAS” to match the STF
indicator (triangle symbol) with the value on the optimal anemometric speed.
N.B. In order to be able to use this function, you must have the Digifly AIR with
Pitot Tube and have the tube installed in your instrument; also you need to have
the Polar data programmed (for example, Polar 1: ADVANCED SETUP \ n. 11-
12-13 P1A-P1B-P1C) and that the Polar parameter itself is enabled to work
with the values you have programmed (for example, Polar 1: ADVANCED SETUP
\ n. 10 POLA=1).
Optimal STF
position
Speed to fly
(STF) indicator
Содержание AIR-BT
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