Balance The Model (C.g.) - GREAT PLANES Shoestring ARF Instruction Manual

indicated in the chart that follows. If your radio does not have
dual rates, we recommend setting the throws between the
high and low rate settings.
NOTE: The throws are measured at the widest part of the
elevators, rudder and ailerons.
These are the recommend control surface throws:
High Rate
ELEVATOR: 3/4" [19mm] up
3/4" [19mm] down
RUDDER: 1-1/4" [32mm] right
1-1/4" [32mm] left
AILERONS: 9/16" [14mm] up
9/16" [14mm] down
IMPORTANT: The Shoestring ARF has been extensively
flown and tested to arrive at the throws at which it flies
best. Flying your model at these throws will provide you
with the greatest chance for successful first flights. If, after
you have become accustomed to the way the Shoestring
flies, you would like to change the throws to suit your
taste, that is fine. However, too much control throw could
make the model difficult to control, so remember, "more is
not always better."

Balance the Model (C.G.)

More than any other factor, the C.G. (center of gravity or
balance point) can have the greatest effect on how a
model flies and may determine whether or not your first
flight will be successful. If you value this model and wish to
enjoy it for many flights, DO NOT OVERLOOK THIS
IMPORTANT PROCEDURE. A model that is not properly
balanced will be unstable and possibly unflyable.
At this stage the model should be in ready-to-fly condition
with all of the systems installed including the engine, landing
gear, covering and paint and the radio system. The fuel tank
should be empty.
3-3/16"
BOTTOM OF WING
1. Use a felt-tip pen or 1/8"-wide tape to accurately mark
the C.G. on the bottom of the wing on both sides of the
fuselage. The C.G. is located 3-3/16" [81mm] back from
the leading edge of the wing where it meets the fuselage.
Low Rate
1/2" [13mm] up
1/2" [13mm] down
3/4" [19mm] right
3/4" [19mm] left
3/8" [9mm] up
3/8" [9mm] down
3-3/16"
This is where your model should balance for your first
flights. Later, you may wish to experiment by shifting the
C.G. up to 7/16" [11mm] forward or 7/16" [11mm] back to
change the flying characteristics. Moving the C.G. forward
may improve the smoothness and stability, but it may then
require more speed for takeoff and make it more difficult
to slow for landing. Moving the C.G. aft makes the model
more maneuverable, but could also cause it to become
difficult to control. In any case, start at the recommended
location and do not at any time balance the model outside
the recommended range.
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 on a Great Planes CG Machine, or lift it at the
balance point you marked.
3. When the model is lifted at the recommended balance
point it is likely that the nose will drop, thus indicating that the
model is nose-heavy and will require tail weight to balance.
However, if the tail drops, the model is tail heavy and the
model will require nose weight. If you haven't already done
so, move the battery pack and receiver to a location that will
minimize or eliminate any additional ballast required. If
additional weight is required to balance the model, 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 lead to the nose is to the firewall (don't attach
weight to the cowl—it is not intended to support weight). If tail
weight is required (as will most likely be the case), it may be
temporarily attached to the bottom of the stab or fuse. When
the amount of tail weight is finalized after test flying, the tail
block may be cut open and weight permanently glued 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 RTV silicone or epoxy to permanently
hold the weight in place.
4. IMPORTANT: If you found it necessary to add any
weight, recheck the C.G. after the weight has been installed.
20
3-3/16"