Setting the tail slider limits
Some Gyros have the ability to limit
the amount of rotation of the servo. To use this option, first slowly
apply left stick (towards the right). If the tail slider makes
contact before the stick is all the way to the right, then use the
limit settings of the gyro to back it off. The idea is to barely
touch the end points of the tail slider travel in both directions.
Use the gyro limitation as your first option, and if that is not
enough, then you can use the End Points option of the program to
prevent the tail slider from binding against the end of travel. You
may have to use a combination of both Gyro limits and End Point
settings to achieve full tail slider movement.
Hint. Once you have the limits set, it
is a good practice to back the limits off slightly so that the tail
slider as a tiny gap between the end points of travel. The reason for
this is because we have not performed the initial test flight so we
will more than likely have to move the tail server on the boom and
this will affect the tail slider limits.
Place some training gear on the
helicopter, and find a hard level surface such as a patio or garage
floor to adjust the tail servo position. All we need to do is get the
servo into the spot along the boom where the helicopter does not spin
at a hover.
We will not be using the HH mode for
this part of the setup. We will initialize the Gyro in HH mode, but
before lifting off, we will change to Rate mode. Once the Rate mode
is dialed in and the helicopter does not spin or drift (with no wind
conditions) we can finalize the setup and move into the fine tuning
stage.
Note: some pilots believe that you can
just set the tail slider in the center, and let the gyro HH mode
figure out what to do. That does work, until your gyro falls out of
HH mode unexpectedly, and then you are in for a fight to get her
landed. Also using that approach puts more work on the gyro and servo
than is necessary. By following the following instructions for
setting up in Rate mode, you will be able to maintain total control
of the tail even if the gyro falls out of HH mode. You may not even
notice it fell out of HH mode until you get her on the ground and see
the red light flashing at you.
Power up the helicopter and turn the
VR(B) gain dial CCW until the Gyro light goes out. When the Gyro
light goes out, the Gyro is in RATE mode. Bring the throttle speed up
until the helicopter is sitting light in the skids. It is normal for
the helicopter to want to spin 45 to 90 degreed on a hard surface
with training gear attached. Just bring it back using the left stick
and increase throttle a little more. If the helicopter begins a high
speed spin, it means the gyro needs to be reversed. In that case,
power down, set the reverse, and try again.
If it takes a lot of left stick to
prevent the helicopter from spinning, then adjust the servo position
on the boom. Small increments until it takes little or no stick to
keep it straight while on the ground.
Once you have the steady tail in Rate
mode on the ground, the next step is to perform a hover in Rate mode.
The same process you performed to get the tail steady on the ground
also applies in the hover.
Once your Rate mode can hold a descent
tail position at a 4-5 ft hover, you are ready to place it into HH
mode. First tighten both servo boom mounting screws.
With it landed, turn the Gain dial
VR(B) CW until the HH mode light on the gyro lights. This is the
lowest gain setting. If the horn starts to drift, use the horizontal
slider to stop the drift. Now with no throttle reset the HH setting
by toggling the gyro in and out of HH mode three times in less than
two seconds. This can be done with either the VR(B) dial, or using
the left stick by rapidly moving left and right three or more times
in under two seconds. Test the hover again. Each time you test hover,
land and increase the gyro gain CW a little at a time. At some point
the gyro will begin to perform a Tail Wag. This is cause by the gyro
commanding a fast movement of the servo, and over-compensates. This
in turn causes the gyro to command the opposite signal, again
over-compensating. Turn the gain CCW until this stops, and then turn
it about 10% more CCW.
Note: Gyros are effected by your radio
rudder trim slider switch. There is a threshold at which the gyro
will assume you are applying stick movement and falls out of HH mode.
When you first power the helicopter, the gyro takes a reading of the
current software and hardware SUBTRIM setting from the radio. That
becomes its reference point. It tells the computer that at this
heading I should have that SUBTRIM value. The Slider trim throws off
that original value, and too much of a change will cause the gyro to
display a high speed indication (led flashing) to show it has lost
its reference, and will no longer attempt to go into HH mode without
a reset. If you have a radio that has a Gain toggle switch, you can
quickly toggle that switch 3 times to tell the gyro to reset, and
re-read your trim settings. Don't try this if you are a beginner
pilot, instead, land and use the dial (between rate and HH within two
seconds) to reset the gyro. Another way of resetting the gyro is to
rapidly toggle the rudder stick max Right then Left three times in
two seconds. Remember that once the gyro enters reset mode, it needs
to be steady in one position with no rudder stick to establish its
new heading. That operation can take up to 7 seconds.
At this point your helicopter is setup for typical beginner
flight. Your Tail servo and gyro settings are complete. Before going
off an starting to fly you need to perform some fine tuning.
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Next - Fine Tuning