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q 1) It is critical that your airplane be balanced
correctly. Improper balance will cause your plane to
lose control and crash. The center of gravity is lo-
cated 3-1/8” back from the leading edge of the
wing, at the fuselage sides. This location is recom-
mended for initial test flying and trimming. There is
a 1/4” margin forward and aft, but it is not recom-
mended that the center of gravity be located any fur-
ther back than 3-3/8”. Balance the Extra 300 upside
down with the fuel tank empty.
q 2) Mount the wing to the fuselage. Using a
couple of pieces of masking tape, place them on the
top side of the wing 3-1/8” back from the leading edge,
at the fuselage sides.
q 3) Turn the airplane upside down. Place your
fingers on the masking tape and carefully lift the plane.
q 4) If the nose of the plane falls, the plane is nose
heavy. To correct this first move the battery pack fur-
ther back in the fuselage. If this is not possible or does
not correct it, stick small amounts of weight on the
fuselage under the horizontal stabilizer. If the tail of
the plane falls, the plane is tail heavy. To correct this,
move the battery and receiver forward or if this is not
possible, stick weight onto the firewall. When bal-
anced correctly, the airplane should sit level or slightly
nose down when you lift it up with your fingers.
Once you have flown and trimmed the Extra
300, the balance point can be moved forward or
aft 1/4” to change the flight performance. Moving
the balance point back will cause the airplane to be
more responsive, but less stable. Moving the balance
point forward will cause the airplane to be more stable,
but less responsive. Do not fly the Extra 300 be-
yond the recommended balance range or an un-
controllable crash could result!
BALANCING
After you have balanced the Extra 300 on the
C.G. you must laterally balance it. Doing this
will help the airplane track better.
q 5) Turn the airplane upside down. Attach one
loop of heavy string to the engine crankshaft and one
to the tail wheel wire. With the wings level, carefully
lift the airplane by the string. This may require two
people to make it easier.
LATERAL BALANCE
q 6) If one side of the wing falls, that side is
heavier than the opposite. Add small amounts of lead
weight to the bottom side of the lighter wing half.
Follow this procedure until the wing stays level when
you lift the airplane.
CONTROL THROWS
q 1) We highly recommend setting up the Extra
300 using the control throws listed below. We have
listed control throws for both initial test flying/sport
flying and aerobatic flying.
q 2) Turn on the radio system and with the trim
tabs on the transmitter in neutral, center the control
surfaces by making adjustments to the clevises. The
servo arms should be centered also.
q 3) When the elevator, rudder and aileron con-
trol surfaces are centered, use a ruler and check the
amount of the control throw in each surface. The
control throws should be measured at the widest
point of each surface!
INITIAL FLYING/SPORT FLYING
Ailerons: 1/4” up 1/4” down
Elevator: 5/16” up 5/16” down
Rudder: 3/4” right 3/4” left
AEROBATIC FLYING
Ailerons: 5/16” up 5/16” down
Elevator: 5/8” up 5/8” down
Rudder: 1-1/4” right 1-1/4” left
Do not use the aerobatic settings for ini-
tial test flying or sport flying.
q 4) By moving the position of the clevis at the
control horn toward the outermost hole, you will de-
crease the amount of throw of that control surface.
Moving the clevis toward the control surface will in-
crease the amount of throw.
FLIGHT PREPARATION
q 1) Check the operation and direction of the
elevator, rudder, ailerons and throttle.
q A) Plug in your radio system per the
manufacturer's instructions and turn everything on.
q B) Check the elevator first. Pull back on
the elevator stick. The elevator should go up. If it
does not, flip the servo reversing switch on your trans-
mitter to change the direction.
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