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Step Five:
Setting the
Rates
Next task is the
rates you fly on. The JR 10X has the advantage here. It has
3 rates automatically built in. Just put the switch in the
position you want and adjust the percentage you want. Expo
is also set on the same screen. The rates are all even
multiples once the BASE ATV or end point adjustments have
been set as accurately as possible. So the rates would be
about 80% (or 8°) of travel, according to our example.
Futaba 9Z series
radios uses a different method for setting the rates. It
has a dual rate (D/R) function screen that controls a single
rate. This is called your dual rate. When the switch is on
for this rate to be active, you're on it. Expo values are
also set in this screen. This is under the D/R option in the
condition menu of the 9Z series. The 9Z also has a function
called AFR or adjustable function rate. This functions
basically the same as "high rate" on most dual rate setups.
Most people set this AFR as the high rate and it's best to
do this. The AFR can give your high rate actually a little
more travel than your ATV allows. But with your ATV’s up
over 120% extending your AFR over 100% can actually drive
your servo to its physical limits rather than the limits of
your control surface. This can be a bad thing and can damage
the servo or the linkage if it's over travels.
By the way, JR
has a similar function called "trace rate." Once your
ATV values or travel adjust on the JR is set and paired for
equal deflection, the trace rate can be dialed up and down
to produce slightly more or less throw, globally, affecting
all the rates. Both AFR and trace rate settings affect all
the servos mixed into the function. For example, AFR on the
aileron channel will affect both ailerons. Of course,
there's no need to adjust the AFR of the flap channel, since
it would only affect the flap functions, and we don’t use
these with pattern models.
Last Step:
Testing Your Linkage
So how do you
decide if you need better control linkages? Look at your
radio settings. If the D/R values that you are flying on are
less than 80% for ailerons then you can improve your linkage
and get more mechanical advantage for your servo.
Ever wonder why
the big 40% models use so many servos on each aileron? It
isn't that the size of the aileron and the force required to
move the aileron demands three or four 200+oz servos. More
often than not, the linkages are set up so poorly that
multiple large servos are required to maintain precision.
The pilot will feel the blow back of the surface.
We can feel this
too on our pattern models, but it's much less pronounced.
Our surfaces are smaller and we put over-kill power on them.
The end result is that they still deflect under load.
It's just less deflection. Proper linkage alignment helps
more than over-kill servos.
The big models
are being flown on 10-15° of aileron throw for precision,
but they need the linkage to put out 45° of travel for the
3D stuff. They have to double the servo power in order to
have enough leverage to hold things precise down at 40-50%
D/R values. In Pattern flying we're not going for 3D,
so we want to maximize the mechanical leverage. This makes
the model fly better. It minimizes the minor slop in gear
sets and pot wear, and it gives us maximum resolution in our
radio.
You want to use
all the radio to help you out, instead of simply trying to
mix out errors. The radio is best used to adjust minor
differences to produce symmetry when making changes or
setting up special mixes for things like knife-edge
maneuvers.
Maximize your
linkages and your model will loop track better. It will
groove better, and it will roll more axially. All of this
and your model will fly more consistently. Then when you go
to a new flying field or different elevation, like the NATS,
your model will only need a couple of tweaks on the rates
and you’ll be just as trimmed as when you left home!
troy_newman@msn.com |
