Problem Solving - Multiplex True Airspeed Notice D'utilisation

6. Problem solving

The table below provides answers to the most
frequently asked questions.
Problem
No speed displayed:
"-.-"
A speed of only 0.0 km/h is
displayed.
The speed is displayed
incorrectly.
After landing, the vario -
altimeter does not show a
height of exactly 0 m.
The vario tone output on
the transmitter does not
work.
The sensor is not detected
by MULTIPLEX Launcher.
The stall warning is trigge-
red too late.
Cause
The sensor cannot carry out the
self-calibration process due to
fluctuating airflow (wind).
Prandtl tube or silicone tubes not
allowing air to pass through.
Silicone tubes connected or ins-
talled incorrectly.
Weather conditions.
Transmitter setting.
Power supply not present.
Physics:
Altitude - ambient pressure dimi-
nishes with altitude. Higher speed
is necessary in order to generate
sufficient lift.
The sensor automatically adjusts
the speed measurement to the cur-
rent altitude. The speed displayed
is therefore always correct.
Remedy
Prevent airflow reaching the Prandtl tube
for the period of the automatic calibration,
e.g. using a cloth or your hand.
Check that silicone tubes are not kinked.
Check that the Prandtl tube is not soiled
or blocked.
Check that both silicone tubes are correct-
ly fitted.
Since the vario operates by monitoring
ambient air pressure, slight variations are
normal, especially if weather conditions
are changeable (low / high pressure).
Check the transmitter settings for vario
tone output. Make sure the address for
the vario function (rate of climb / descent)
is correct.
Read the "Configuration" chapter. You
must connect a receiver battery using the
Y-lead as well as the sensor.
For each 1000 m of height you expect the
model to reach, set an additional speed
reserve of +5% for the stall warning.
Example:
Your model is trimmed to fly at a height of
10 m above sea level. The stall speed is
45 km/hr.
When flying in mountains at a height of
1010 m above sea level the stall speed
rises to 47.25 km/hr
(45 km/hr = 100%)
(47.25 km/hr = 105%)
GB
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