6
http://www.jperkinsdistribution.co.uk
http://www.jperkinsdistribution.co.uk
http://www.jperkinsdistribution.co.uk
automatically compensates for torque changes and
helps stabilise the tail making for much easier flight.
Steering control - cyclic control
The main directional or steering controls in a
helicopter are known as the 'cyclic' controls and
work by directing the thrust generated by the main
rotor blades in the direction required for flight.
When helicopter main rotor blades are spinning
in flight you will often be able to make out what
looks like a disc - as the blades blur with speed and
viewing angle. This is known as the 'rotor disc' and
is operated by the cyclic controls on the right hand
stick of your transmitter.
Steering control - fore and aft cyclic
When hovering, a brief forward push on the cyclic
control stick will tilt the rotor disc forward causing
the helicopter to accelerate in that direction. By
pulling the stick back, any forward speed gained
will be reduced as the rotor disc tilts backwards
and thereby reverses the thrust generated by the
forward stick command.
Steering control - roll cyclic
When hovering, a brief right control stick movement
will roll the rotor disc to the right and the helicopter
will start moving to the right. By briefly moving the
stick to the left any right drift or movement will be
arrested or reduced.
A helicopter in the hover behaves in an analogous
way to a stick balanced vertically on ones finger
- small movements of your hand will be required in
order to prevent the stick from accelerating away
from the vertical and falling to terra firma!
Both experienced model and full-size pilots in
the hover will gently 'nudge' the cyclic controls
automatically in order to keep their helicopter in one
spot and prevent it from accelerating away down
the flying field.
A large part of the initial learning phase in
helicopter flight is about mastering the cyclic
controls so that their correct use in the hover or
whilst 'ground handling' becomes automatic and
instinctive.
Cyclic controls in detail
In order to fly and maintain a model helicopter a
basic understanding of the control mechanisms
involved is required.
The sequence of control works like this:
As the cyclic transmitter stick is moved forwards, a
pulsed signal is picked up by the receiver in the '4
in 1' control unit which is passed to the proportional
fore and aft cyclic servo mounted in the model.
The servo output arm operates the 'swashplate'
tilting the swashplate forward. The swashplate is
connected by linkages to the flybar and control
paddles. The paddles are small 'wings' in their own
right and are connected to the rotor head. It is the
paddles that effectively drive the main rotor blade
angle and hence move the rotor disc forwards/
backwards or left/right.
When the forward cyclic command is released the
swashplate is returned to the horizontal position
and the rotor disc follows suit.
