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required to fly your EXTRA 300XS - rudder, elevator, ailerons, and
throttle. However, you will require a total of six servos - ailerons
(2), elevators (2), rudder (1), and throttle (1).
SERVOS: Since your EXTRA 300XS is a large, highly aerobatic
airplane and because the control surfaces are also large, we urge
you to use appropriate servos on all the flight surfaces (ailerons,
elevator, and rudder).
This model should not be flown with
"standard" 40 - 50 inch/ounce output servos! The EXTRA is big
enough to impart very large air loads and standard servos will
quickly fail, resulting in loss of control. You should use heavy-duty
ball-bearing servos with at least 70 inch/ounces of torque or more to
drive the ailerons, elevators, and rudder. If available, use a servo
with metal gears instead of plastic gears.
Specifically in our
prototype models we used Airtronics
®
#94731 servos for the ailerons,
elevators, and rudder. This is a dual ball-bearing servo, rated at 77
inch/ounces of torque. Another good choice is the Hitec™ #605MG
servo which has 76 inch/ounces of torque and metal gears. These
servos or their equivalent from other manufacturers, can be relied
upon to work well throughout the EXTRA's flight envelope.
A
"standard" servo is adequate for the throttle.
SERVO ARMS: We also suggest that you consider using after-
market reinforced plastic servo output arms, such as the Du-Bro
"Super Strength" products. These output arms are available to fit
any brand of servo. They are very strong and work well with this
model. We highly recommend their use with the pull-pull rudder
system used in this EXTRA. Using typical plastic servo output
arms with the braided steel cables for rudder control, may cause
problems due to the potential of wearing of the plastic by the
cables over extended use. The Du-Bro output arms are molded
from considerably tougher material and these have held up
extremely well in our prototypes.
SERVO EXTENSION CHORDS:
You will need two 12" servo
extension chords for the ailerons, one standard Y-harness chord for
the two aileron servos and one Y-harness chord for the two
elevator servos. The Y-harness chords are used to connect two
servos to a single connector going into the receiver. In the case of
the two aileron servos a standard Y-harness chord, available from
your radio manufacturer, will work fine. In the case of the two
elevator servos see the following note about a great product called
the "Miracle Y".
MIRACLE "Y": Note in the photos that the elevator servos will be
mounted on opposite sides of the fuselage in exact "mirror image"
to each other (i.e.; with the pushrods coming off the top of each
servo in direct line with the control horns). This is done so the
geometry of the servos, pushrods, and horns is exactly symmetrical
on both sides, providing the exact same response to control inputs
for each elevator. This is very important in an all out aerobatic
machine like the EXTRA! Normally in order to have this type of
setup work properly with a standard Y-harness you would have
EXTRA 300XS ARF ASSEMBLY MANUAL
INTRODUCTION:
Congratulations on the purchase of your SIG EXTRA 300XS ARF
kit! Properly assembled, powered and flown, the EXTRA 300XS
will surely become one of your favorite models. The construction
of this ARF kit is extremely well engineered, providing a structure
that is very light and strong. This is one of the reasons it flies as
well as it does, using the recommended engine sizes. The EXTRA
300XS has superb take-off and landing characteristics combined
with remarkable aerobatic capabilities. The airframe has been
specifically designed to provide you with a "zeroed out" model.
This is to say that the wings and horizontal stabilizer sit at 0
O
in
relationship to the thrustline. In turn, this provides you with a model
that is completely "honest" in any attitude. We will cover more
detailed set-up information later in the assembly instructions.
3D CAPABLE!
For those of you who are interested in 3-D
aerobatics, we have provided the EXTRA 300XS with double
beveled elevator and rudder hinge lines. This means that the
control surfaces can be driven to throws in excess of 45
O
for
extreme 3-D maneuvers!
ENGINE NOTE:
Due to the large number of useable engines
for this model, we simply cannot cover every possible engine
installation. However, the volume of space provided inside the
large cowling should make it easy to mount virtually any engine
within the suggested size range.
EASY TO ASSEMBLE! Since the general construction, sanding
and covering of the airplane have already been done at the
factory, the only remaining tasks are those of final assembly and
radio and engine installations.
We urge you to follow these
assembly instructions closely to produce the model as it is
intended to be.
We understand that many modelers love to
"kit bash" and incorporate their own modifications.
Simply be
aware that certain assembly procedures for this airplane must
be followed in the correct sequence.
Deviation from these
instructions could lead to problems beyond our control.
Plan
carefully!
ADDITIONAL ITEMS NEEDED TO COMPLETE THIS MODEL
RADIO EQUIPMENT
We highly recommend the use of a modern programmable
computer radio. Such radio systems allow you to easily set and
adjust every channel and additionally pre-program various flight
functions to suit your individual style of flying. Four channels are