When the helicopter lands, the fuselage rotates forward parallel to the ground, but
the main rotor blades continue their downward and backward motion and eventually
strike the tail boom. To avoid this problem, apply forward cyclic pressure as your
helicopter touches the ground. Forward cyclic also tends to keep the tail rotor high
when landing in tall grass.
Lite Machines helicopters tend to rotate to the left when you suddenly drop the
throttle after landing. By suddenly lowering the throttle you remove the engine torque
driving the main rotor, but the main rotor and tail rotor are still turning at high speed.
The thrust force produced by the tail rotor pushes the nose of the helicopter to the left.
To make your landings more precise, reduce the throttle slowly after touch-down, or
apply right tail rotor control when reducing throttle. For more information on tail
swing, refer to the
Tail Swing and Revo Mix
section of this Operator’s Guide.
Piezo Gyro Stabilizers
The tail rotor of most helicopters is connected directly to the main rotor. As a result,
the main rotor and tail rotor change speed at the same rate. This means that changes
in engine torque are roughly compensated for by changes in the thrust of the tail
rotor. As long as throttle changes are made slowly and smoothly, your Lite Machines
helicopter will tend to climb and descend without much tail swing.
The main rotor and tail rotor, however, cannot change speed instantaneously. If you
suddenly increase or decrease throttle, the change in engine torque will cause the tail
to swing. Electronic gyro stabilizers such as piezo gyros sense rotational motion of
the helicopter body and control the tail rotor servo to slow down or stop the rotation.
Gyro stabilizers reduce tail swing considerably, but not completely.
Piezo gyros (which use a piezo-electric crystal) are sensitive to vibration and
temperature changes. A vibrating gyro will send continuous small commands to the
tail rotor servo and eventually wear out the servo. To reduce the likelihood of damage
to the gyro and tail rotor servo, isolate the gyro from vibration with foam mounting
tape or other soft insulation.
In winter, if you store your helicopter in a warm car, and fly in cold air, your piezo gyro
may malfunction as it changes temperature causing your helicopter to lose control.
Always allow your gyro to come to temperature before flying.
Most all electronic gyros have a “gain” control to adjust the amount of gyro
stabilization fed to the tail rotor servo. One way to find the best gain is to start at 50%
of full gain and fly your helicopter. If the nose tends to wander or swing in unwanted
directions, turn the gain up and fly again. If the tail tends to wave back and forth like a
fish swimming, turn the gain down.
Hint:
Gyro stabilizers sense only rotational motion. It does not matter where on a
helicopter a gyro is mounted as long as it is orientated correctly and does not vibrate
excessively. Contrary to common wisdom, mounting the gyro near the main rotor
shaft is unnecessary.
Op er a tor's Guide
Learning to Fly
6-12
LITE MA CHINES
