16
Balance the Model (C.G.)
More than any other factor, the
C.G.
(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 in place including the motor, landing
gear, wings, and the radio system.
❏
1. Use a felt-tip pen or 1/8" [3mm]-wide tape to accurately
mark the C.G. on the top of the wing at the side of the
fuselage. The C.G. is located 3-7/8" [97mm] back from the
leading edge of the wing at the side of the fuselage.
This is where your model should balance for the first
flights. Later, you may wish to experiment by shifting the
C.G. up to 3/8" [9.5mm] forward or 3/8" [9.5mm] back to
change the flying characteristics. Moving the C.G. forward
may improve the smoothness and stability, but the model
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 too difficult to control. In any case,
start at the
recommended balance point
and do not at any time
balance the model outside the specified range.
3-7/8" [97mm]
❏
2. With the wing attached to the fuselage, all parts of the
model installed (ready to fly) and a flight battery installed, lift
the plane at the balance point you marked.
❏
3. If the tail drops, the model is “tail heavy” and the battery
pack 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 must be shifted aft or weight must be
added to the tail to balance. If additional weight is required,
use Great Planes (GPMQ4485) “stick on” lead. A good place
to add stick-on nose weight is to the motor box (don’t attach
weight to the cowl—it is not intended to support weight).
Begin by placing incrementally increasing amounts of weight
on the fuse over the motor box until the model balances.
Once you have determined the amount of weight required, it
can be permanently attached.
NOTE:
Do not rely upon the adhesive on the back of the
lead weight to permanently hold it in place. Over time the
adhesive may soften and cause the weight to fall off. Use #2
sheet metal screws, 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.
Balance the Model Laterally
❏
1. With the wing level, have an assistant help you lift the
model by the motor propeller shaft and the bottom of the
fuse under the TE of the fin. Do this several times.
❏
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.
PREFLIGHT
Identify Your Model
No matter if you fly at an AMA sanctioned R/C club site or if
you fly somewhere on your own, you should always have your
name, address, telephone number and AMA number on or
inside your model. It is
required
at all AMA R/C club flying sites
and AMA sanctioned flying events. Fill out the identification tag
on page 19 and place it on or inside your model.
Charge the Batteries
Follow the battery charging instructions that came with your
radio control system to charge the batteries. You should
always charge your transmitter batteries the night before you
go flying, and at other times as recommended by the radio
manufacturer.
CAUTION:
Unless the instructions that came with your
radio system state differently, the
initial
charge on
new
transmitter and receiver batteries should be done for 15
hours
using the slow-charger that came with the radio
system
. This will “condition” the batteries so that the next
charge may be done using the fast-charger of your choice.
If the initial charge is done with a fast-charger the batteries
may not reach their full capacity and you may be flying with
batteries that are only partially charged.
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