FES Discus 2c - Low-Speed Flight and Stall Behaviour; Cruise and Climb with a Running Motor

FES Flight Manual, v1.18 May 2020
Page 21 of 35
4.5.7 Low-speed flight and stall behaviour
As described in the manual of the pure glider version of the sailplane, but keep in
mind that your FES equipped glider has around 5kg/m2 higher wing loading, and as a
result, higher stall speed.
4.5.8 Cruise and climb with a running motor
FES can be used for a long continuous cruise at low power settings or for climbing at
higher power settings.
Caution: During motor operation, ventilation must be fully opened. The
opening procedure depends on the type of sailplane; usually, the ventilation
lever must be pushed fully forward.
Warning: I case that you forget to open ventilation; warning message
“Check ventilation” will appear on the FCU screen. FCU monitors temperature
rise gradient. When it becomes steeper than usual, the message will be
displayed.
Motor starting procedure during flight:
1. Check that all values on the FCU instrument are in the normal range. The FCU must
always be switched ON during flight.
2. Turn ON the Power Switch.
3. Check if the green "OK" LED is ON. Check Voltage level.
If there is no green LED or the red LED is blinking, the motor will not run. Read FES
FCU instrument manual for a detailed description.
4. Start the motor by rotating the throttle knob clockwise gently.
Set power to 4kW for horizontal flight and more for climbing. Maximum climb rate
depends on glider type, and it is affected by its weight, speed, flaps position etc.
Maximum available power is reduced slowly during operation, due to the voltage
drop from draining power from battery packs. Maximum power is accessible until any of
the temperature values reach a yellow warning level. These levels are 70°C for the motor
and controller and 45°C for battery packs.
Note: You can reduce power in thermals and use more energy in sinking air.
Do not use high current when the total battery voltage is below 95V. Try to fly with
lower power settings as much as possible, where the efficiency of the complete system is
the best!
Always keep the FCU turned ON during flight.
Switch OFF the power switch if the motor is not running.