Great Planes Extra 300S 1.60 ARF - GPMA1365 - Manual (Page 20)

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2. With the wing attached to the fuselage, all parts of the
model installed (ready to fly) and an empty fuel tank, place
the model upside-down on a Great Planes CG Machine, or
lift it upside-down at the balance point you marked.
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3. If the tail drops, the model is “tail heavy” and the
battery pack and/or receiver must be shifted forward or
weight must be added to the nose to balance. If the nose
drops, the model is “nose heavy” and the battery pack
and/or receiver must be shifted aft or weight must be added
to the tail to balance. If possible, relocate the battery pack
and receiver to minimize or eliminate any additional ballast
required. If additional weight is required, nose weight may
be easily added by using a “spinner weight” (GPMQ4645 for
the 1 oz. weight, or GPMQ4646 for the 2 oz. weight). If
spinner weight is not practical or is not enough, use Great
Planes (GPMQ4485) “stick-on” lead. A good place to add
stick-on nose weight is to the firewall (don’t attach weight to
the cowl—it is not intended to support weight). Begin by
placing incrementally increasing amounts of weight on the
bottom of the fuse over the firewall until the model balances.
Once you have determined the amount of weight required,
it can be permanently attached. If required, tail weight may
be added inside of the hatch on the bottom of the fuse and
gluing it permanently inside.
Note: Do not rely upon the adhesive on the back of the lead
weight to permanently hold it in place. Over time, fuel and
exhaust residue may soften the adhesive and cause the
weight to fall off. Use #2 sheet metal screws, RTV silicone
or epoxy to permanently hold the weight in place.
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4. IMPORTANT: If you found it necessary to add any
weight, recheck the C.G. after the weight has been installed.
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1. With the wing level, have an assistant help you lift the
model by the engine propeller shaft and the bottom of the
fuse under the TE of the fin. Do this several times.
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2. If one wing always drops when you lift the model, it means
that side is heavy. Balance the airplane by adding weight to the
other wing tip. An airplane that has been laterally balanced
will track better in loops and other maneuvers.
The Great Planes Extra 300S 1.60 ARF will perform 3-D
aerobatics easily if you use the largest engines
recommended within the engine range. If you setup your
airplane to do 3D maneuvers, you will need to be throttle
conscious; that is, never apply full throttle on straight and
level flying or in dives to prevent flutter.
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1. Because 3D flying requires very large control throws
you need to mount the servo arm so that it is pointing
towards the bottom of the fuselage instead of towards the
stab as shown on page 13 of the instruction manual. This
also requires that you mount the control horn at the very
bottom of the rudder. The standard aerobatic linkage set up
is a very straight linkage between the servo and the rudder
but there is a chance that at the extreme ends of the
3D Rudder Servo/Control Horn
Installation
ELEVATOR: 3/4" up 3/4" down
[19.1mm] [19.1mm]
RUDDER: 6-1/2" right 6-1/2" left
[165.1mm] [165.1mm]
AILERONS: 2" up 2" down
[51mm] [51mm]
3D Control Throws
3-D PERFORMANCE SETTINGS
Balance the Model Laterally
5-1/2"
[140mm]
20