Here's the difficult part. Getting the heli
properly trimmed. A heli which is trimmed means that
during a hover, all the control trims on the Tx is
at centre. This is ideal, but this is not always the
To begin, make sure that your servos center point
is neutral with the control surfaces. ie: With your
swashplate level, your aileron and elevator servos
should be at center, with the control sticks also at
center position. Rudder is difficult, so follow your
instruction manual on pre-setting the rudder. Only
during your first hover would you know how much
rudder trimming you need.
Setup your gyro, and pay careful attention to the
way your gyro moves in conjunction with the way you
swing the heli. You would want the gyro to counter
Set up your throttle and pitch curve the way you
want it. How I normally set mine (using a Futaba
Skysport Heli Radio), is to set the throttle first,
then the pitch.
With the Throttle stick at 50% Center, open up
the throttle lever on your engine to 50% (approx),
and then fit the horn into the servo gear. Next,
push the throttle trim to minimum, and the throttle
stick to minimum as well. Your throttle should be
fully closed. Make sure the linkages do not buckle.
If your throttle is not at the fully closed
position, there should be a pot (or computer)
setting to adjust the Low end travel. Adjust this
until the throttle fully closes without buckling the
Now push throttle stick to high, and the throttle
should fully open. As before, if the throttle is not
fully opened or the linkage is buckling, then adjust
the throttle pots (or computer) for the high end
This setting should make your throttle quite
linear. Re-adjust later if you find your head speed
to be off.
For the pitch setting, set your throttle stick to
centre, and with a pitch gauge, set the pitch for
hovering (5 to 6 degrees), and mount the linkage to
the servo gear. Push the throttle fully low, and
then check the pitch. Adjust your pot (or computer)
to give you the pitch you want. If you are unable to
attain the pitch you desire, use a longer servo
horn. Do the same for the high side. Normally, for
starters, -1 to 10 degrees is ideal.
Therefore, we can summarise it as follows:
||0% (trim at min)
Lastly, CENTER OF GRAVITY (CG) has to be right in
the middle of the rotor mast! If it's not, use
weights to adjust the position till it's there.
Once you have completed the preliminary setup,
it's time to fuel up and trim up the entire heli.
Rev up the throttle, and wait until you get a
good constant sound from the engine. Then increase
the throttle slowly until the heli is very light on
its feet. At this stage, your heli will start to
move in all directions. Counter the heli movements
by controlling your cyclic and rudder. For the first
timers, this may be impossible, so get someone to
help if necessary. Also, put the big cross sticks
with balls at the end to save $$$$ in case anything
happens. Trying to be macho here won't gain points
Natural movements of the heli will be as such.
For a clockwise turning rotor, your heli will
tend to drift to the left, due to the tail rotor
pushing to counter the torque. This is normal, and I
normally just push my aileron trim 2 to 3 clicks
Pushing the aileron right to counter will cause
the tail to rise, because of the slight angle, and
this is countered by a little back elevator.
During the hover, your tail should be rock steady
On increasing throttle, your heli (head) will
swing left, but the gyro should counter it slightly,
and on decreasing throttle, the heli will swing
If your heli behaves in this manner, then you got
a properly trimmed heli.
If the tail drops during lift off, your CG is too
far back. Use a heavier battery or some weight to
counter it. Same goes for the opposite. But if the
CG is correct, check the swashplate. It might not be
If your heli drops severely left or right, the
swashplate is probably not level. Check direction,
Tail swings left (head right) during hover.
Rudder linkages too much positive degree. Adjust the
linkage to reduce the rudder pitch.
Tail swings right (head left) during hover.
Rudder linkages too little degree. Adjust the
linkage to increase the rudder pitch.
Tail starts to wag. Your gyro gain is too high.
Note: If your heli is a counter-clockwise
rotation rotor, then the effects will all be
opposite of the above.