Helicopter mechanics
with model turbine engine
50
Setting up the fuel pump
Once the turbine has ignited on propane gas, engine speed continues to increase due to the
action of the starter motor. At 3600 rpm the ECU switches on the fuel pump at minimum power.
Starting from this initial voltage, the pump is fed a slowly increasing voltage, causing the turbine
to increase speed steadily. The voltage which is supplied to the pump immediately after ignition
is pre-set at the factory before shipping. However, if you replace the fuel pump or the ECU it
may be necessary to adjust the initial pump voltage.
The ECU includes a special function for adjusting the initial pump voltage; it can be called up as
follows:
1. Cut off the fuel supply to the turbine (one method is to run the fuel feed line back into the
tank overflow). If you don’t cut off the fuel supply, the adjustment process will flood the
turbine with fuel, and this inevitably leads to a "hot start" next time you attempt to start the
engine!!!
2. Switch off the electronics and connect the GSU (RC transmitter not required).
3. Press and hold the "Change Value/Item" button on the GSU.
4. Switch on the electronics.
5.
Wait until the GSU screen shows the following message, then release the button:
Pump start volt.
Uaccelr1:
The pump can now be started and tested by pressing and holding the "RUN" button.
•
Press the "(-)" button to decrease the initial voltage by one increment.
•
Press the "(+)" button to increase the initial voltage by one increment.
The initial voltage should be set in such a way that the pump runs reliably at every setting, and
the fuel is metered "drop by drop" (you may need to press the RUN button repeatedly).
The proven range of values for the initial voltage is 0.1 to 0.25 V (default value: 0.2 Volt).
Press the "Manual" button to store the newly established setting once you have completed the
adjustment process; you are then returned to normal operation.
The following general rule applies:
Initial voltage too low:
If the initial voltage is set too low, a voltage will be supplied to the pump, but it may be too
low to start the pump running (-> red “pump running” LED lights up, but pump does not
rotate). The likely result of this situation is that the turbine will ignite, but may run for a
very long time on the propane gas. It will not pick up speed, as no fuel is being pumped
into it. If the propane run period is excessive (> 10s) the electronics will terminate the
start process with the following error message “AccTimOut” (= acceleration time-out -
excessive time for speed rise process), or “Acc. Slow” (= acceleration too slow).
Initial voltage too high:
If the initial voltage is set too high, too much fuel is injected into the engine at start-up,
and this may cause dangerous flames at the turbine efflux during the initial start-up
phase. This is caused by inadequate turbine speed relative to the amount of fuel being
injected.
Содержание JetCat 6810
Страница 31: ...31 Bedienungsanleitung ...
Страница 101: ...31 Operating Instructions Graupner Jetcat Modell Helicopter Turbine PHT 3 ...
Страница 107: ...37 Wiring diagram fuel pump and starter glowplug Connections overwiew of the turbine s operating components ...
Страница 171: ...31 Instructions d utilisation ...
Страница 177: ...37 Schéma de connexion Pompe à carburant et Starter Bougie Connexions des éléments de commande Généralité ...
