34
Computer Radio
Enhancements
A computer radio will allow you to do quite a bit of fine tuning of
the feel of the Extra, which will make aerobatics even easier.
Below are the programming enhancements I normally use to trim
out an aerobatic model.
Differential Mixing
This is a great mixing feature of many computer radios that
allows you to dial in the aileron differential, which is how the roll
axis of the model is set. The best method for setting this is to use
the Travel Adjust (ATV) of aileron and flap channels to set the up
and down movement of each aileron exactly the same. Set it to
the maximum throw of 2
1
/
2
" (37°). Then set the differential by
going to the appropriate screen in the radio and adjusting the
differential value to reduce the down movement of each aileron
to 2
1
/
4
" (35°).
Rudder to Elevator and Rudder to Aileron Mixing
This mix is used to dial out unwanted pitch and roll caused by
the rudder. The Extra has very little coupling, but dialing it out
will make knife edge maneuvers easier. Use a preprogrammed
mix if your radio has this feature, or if not, use a P-mix feature.
Assign rudder as the master channel and elevator as the slave.
Set the mixing values so when the rudder is deflected all the way
in either direction on high rate, the elevator moves up
1
/
4
" (2
1
/
2
°).
In another P-mix, assign rudder as the master and aileron as the
slave. Deflect the rudder to full left on high rate and set the mix
value so that the ailerons deflect to the right
1
/
16
" (1°). Then
deflect the rudder to full right and set the mix value so the
ailerons deflect left
1
/
16
" (1°). You may have to tweak your values
a few percent to get it perfect. When its right, the Extra should fly
straight when on knife edge and not roll at all or track to the top
or bottom of the fuselage.
Spoileron Mixing
This can be achieved by using either a preprogrammed elevator
to flap mix or a P-mix. Assign elevator as the master channel and
flap as the slave. Set the mix values so that when full up, 3D
elevator is given, both ailerons also go up
7
/
16
" (16°). This mix
helps stabilize the model in some 3D maneuvers such as the
Elevator and Harrier.
Throttle Curve
This is normally a preprogrammed function. It can also be
achieved in radios that do not have this premix but do have curve
type P-mixing by mixing throttle as the master and slave
channels. Then adjust the curve to get the desired throttle servo
response. This is particularly useful to get an engine to “act”
linear through out the entire throttle stick movement. I also use
this at times to make the throttle response less sensitive in the
rpm ranges used for hovering the model. This makes altitude
control easier and smoother when doing Torque Rolls.
Rates and Expos: when and
where to use them
I always use Expo to soften the feel of the model. On high 3D
rates I use quite a bit. The goal on 3D rates is to get the model to
feel the same around neutral as it does on low rates.
I use low rate settings for all flying except for 3D aerobatics. For
precision flying or general sport hot-dogging, the low rate
throws are perfect, even for snap rolls. The only exception is
rudder rates. I go to 3D rate when doing stall turns and rolling
circles, since the more rudder the better for these. When doing
3D aerobatics, I normally flip to 3D rates just before the
maneuver. As soon as the maneuver is done, I flip back down to
low rate to avoid over-controling the model.
Let’s Get Down To It
When flying aerobatics with a larger model, you will find that it
will do everything just like a smaller model….only better and
easier. There are just a few exceptions to how things are done.
Throttle management is a must. You have to throttle back to idle
when the nose is pointed down.
Snap Rolls
Just like the need to be throttle managed like a full-scale
airplane, larger aerobatic airplanes need to be snapped like a full
scale. Don’t feel bad if this seems like a big “What are you
talking about?” to you. It took me quite a while to figure this out.
Let’s back up to how we all learned to do a snap roll. If it’s an
inside (positive) snap, we pull the sticks into the corner, i.e. full
up, full aileron, and full rudder in the same direction as aileron.
When we want to stop snapping, we release the controls. For
smaller models, this technique not only works but is normally
the only way to get the model to snap. In a full-scale aerobatic
plane, as well as with large models, snaps are different,
particularly on the new breed of aerobatic birds like the Extra
330L, which have large control surfaces.
Unloading Snaps
That’s the whole trick. To start a snap roll, the same method, as
with a smaller model, is used. Pull full up, full rudder, and
aileron in the same direction. But soon as the sticks reach the
corners, neutralize the elevator while keeping the rudder and
ailerons at full deflecion. When you do this correctly, the Extra
will not get “deep” into snaps. This allows it to keep more
airspeed as it exits the snap, so it stops snapping where you
what it to and flies out with more air speed. You’ll also find that it
will be a lot easier to exit a snap heading the same direction you
were when you entered the snap. It’ll take a little practice to get
the hang of “flying” the snaps, but I’ll bet you’ll see a big
improvement in the quality of your flying.
Setup and Flying
CONTINUED
by Mike McConville
