37
The Prototype Model Setup
All of the recommended settings in this manual
are a result of the flight testing on the prototype
Extras. There are no secrets. If you follow the
instructions and these tips, your Extra will be
set up just like mine.
Although a computer radio is not mandatory, it is
preferable in this model. I use Exponential on all
controls to soften the feel around neutral. This makes
it easier to fly smooth in precision maneuvers and
also makes it less likely to over-control in 3D mode. I
use the following expo values:
El38% Low Rate, +70% 3D Rate
A40% Low Rate, +55% 3D Rate
25% Low Rate, +50% 3D Rate
Note that + expo values soften the neutral with JR™
radios. Other brand systems may require “-”
(negative) expo values to soften the neutral.
I have flown Extras equipped with both JR 8101
servos and JR 8411 digital servos. While both are
excellent choices for the Extra, I personally prefer
the feel with the digital 8411 servos; the model feels
slightly more responsive with these servos. I
use a 6V Ni-Cd battery pack equipped with a 5.7V
regulator for maximum speed and torque
from the servos.
The prototype Extras were tested on both the
Zenoah® G62 as well as the Zenoah GT80. With the
G62 for power, the performance was very good sport
power. Vertical performance was good but not
unlimited. I used a Pro-Zinger 22 x 10 prop for all
testing. Even some 3D maneuvers such as Harriers,
Blenders, and Harrier landings were possible;
anything that did not require unlimited vertical.
My personal favorite powerplant is the Zenoah GT80.
I use a Bolly 24 x 10 propeller, which the GT80 turns
at approximately 7000 rpm, and a preshaped and
balanced Bolly 24 x 10 at 7700 rpm. Both work well,
but I feel the preshaped prop has the edge in
hovering maneuvers. This combination has proven to
be totally unlimited and allows anything imaginable
from torque rolls just a few inches off the ground to
multiple vertical snaps.
I found that adequate engine cooling is very
important with the GT80 and strongly recommend
adding the cowl baffles and cutting the cowl bottom
hole to the size recommended in the instructions.
When this was done, the performance difference was
dramatic. If you aren’t getting this kind of
performance, take a look at the cowl and how well
the GT80 is being cooled.
Performance Tip
: Drill eight 5/16" diameter
holes through the internal baffle plate in the
GT80 mufflers. I drilled seven through the
intake opening and one up through the
exhaust stack. Just be sure to flush out all
of the metal shavings from the mufflers.
This little 10-minute trick will add 300 rpm
to the top end.
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°).