User manual

DodoSim 206 FSX User Manual

Page 21

Moving the cyclic left or right will cause the main rotor to be deflected in either direction

respectively. At slow speeds the helicopter will begin to gain speed in that direction but the

tendency of the fuselage and vertical stabiliser, (the “tail fin”), will cause it to try and weathervane,

turning the nose into the direction of travel. Similarly, power may need to be adjusted to retain

height.

3.3.2.2 The Collective “Lever”

Protruding from the central column and resting above the centre pedestal to the left side of the

pilot's seat is the Collective lever. This lever controls the pitch on both main rotor blades at the

same time and thus determines the actual thrust that the disc is generating. Therefore, to increase

thrust the lever is raised and more air is displaced downwards through the rotor disc. To decrease

thrust the lever is lowered.

Hint: Users familiar with cheaper radio-controlled helicopters might not be familiar with collective

pitch. Many low-cost RC helicopters use a fixed-pitch rotor and variable rotor speed to determine

the thrust produced. More expensive RC helicopters utilise collective pitch on both the main and

tail rotors to modulate the thrust generated by them whilst trying to maintain a constant rotor RPM,

as do real helicopters.

3.3.2.3 The Anti-Torque “Rudder” Pedals

Under the pilot’s feet sit two opposing pedals. Unlike an automobile’s accelerator and brake

pedals, these are mechanically linked and movement on one causes opposing movement on the

other. The pedals are used to adjust the thrust generated by the tail rotor. The primary function of

the tail rotor is not for turning, but to oppose the “Torque Induced Yaw” exerted on the airframe by

the transmission. Simply put, (as this is described in more detail later), the action of the engine

turning the rotors in one direction also tries to turn the body of the helicopter in the other. At speed

this effect is largely compensated for by the aerodynamic shape of the fuselage and vertical

stabiliser, (tail fin), but at low speeds and whilst hovering the pilot must exert significant left pedal

control to retain a constant heading.

At low speeds, increasing or decreasing pedal movement will either increase the opposition to the

torque-induced yaw, causing the nose to turn to the left, or reduce it, causing a turn to the right. In

faster forward flight the tail rotor’s effectiveness is lessened by the aerodynamic shape of the

fuselage and vertical stabiliser and is largely only used to keep “the ball” in the centre of the turn

indicator to ensure co-ordinated flight.

3.3.2.4 The Engine Throttle

The engine throttle is a twist-grip on the body of the collective pitch lever. In a piston powered

helicopter without an engine speed governor it is often used constantly by the pilot to modulate the

engine speed to ensure the rotor RPM remains within safe limits. As aerodynamic stresses are

placed upon the aircraft by manoeuvring, the pilot has to constantly compensate for the resulting

changes in rotor RPM. In a turbine-powered helicopter such as this, the engine is fitted with a

“governor”, which automatically adjusts engine speed in an attempt to keep rotor RPM within limits.

Therefore, once started and ready to fly, the pilot never usually has cause to touch the throttle

again until after landing. Use of the throttle shall be discussed thoroughly later on in this manual.

Though similar in concept to a motorcycle’s twist-grip throttle, the helicopter’s does not snap shut if

released, but remains in position.