3
motor, until the point where the rotational speed is high enough for the turbine to run entirely on
kerosene.
Once the engine is running and a stable idle speed has become established, control is passed
to the pilot. The pilot uses a slider on the transmitter to increase the rotational speed of the tur-
bine slowly until the desired system speed is reached. Any system rotational speed set on the
slider is governed by the on-board electronics, and remains constant within broad limits re-
gardless of the load on the system. As a result, main rotor thrust is controlled exclusively via
collective pitch, as the rotational speed is regulated by the turbine electronics. At the end of a
flight the turbine’s rotational speed is run down to idle again by the pilot in the same way, then
the same channel is used to initiate the power-down procedure. This process is again entirely
automatic, under the control of the on-board electronics: first combustion is halted, then the
starter motor is switched on to force fresh air through the turbine until the internal temperature
has fallen below 100°C; an LED on the model indicates the end of the cooling-down phase, and
the receiving system can then be switched off.
Flying a model helicopter with a turbine power system turns out to be an extremely pleasant
experience, provided that the pilot makes allowance for the system’s inherent characteristics.
The power development of a turbine is always smooth, with no detectable non-linearity in the
torque curve - a feature of piston engines which is familiar to all of us, and which leads to ir-
regular and spasmodic movements of the tail boom. For this reason a turbine heli is substan-
tially smoother around the vertical axis than any model powered by a piston engine or electric
motor. Turbines also feature extremely low vibration levels; this ensures that the radio control
system components have an easy time and last correspondingly longer, and it also means that
it can make sense to add further fine details to scale models. Admittedly the characteristically
"smooth" power development of the turbine does call for a slightly different approach from the
pilot to the collective pitch control, i.e. smooth, harmonious control commands are the order of
the day.
All components, including fuel pump, glowplug, starter and ECU, are powered by a single six-
cell battery which is independent of the receiver power supply.
The display and programming unit (GSU) supplied in the set features a back-lit two-line alpha-
numeric screen as well as 10 operating buttons and 4 LEDs. It can be connected to the engine
when it is running in order to display current operating data, and is also used to change set-up
parameters and read out flight data and static data.
A hydraulic rotor brake is available as an optional accessory; it is servo-operated and has two
purposes: it slows down the main rotor quickly after switching the engine off, and it also helps to
prevent a rotor blade ending up over the exhaust efflux during the start-up phase.
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 ...