Great Planes Spirit of St. Louis ARF - GPMA1152 - Manual (Page 16)

IMPORTANT: The C.G. (center of gravity), or balance point
has the greatest effect on how a model flies. Do not overlook
this important procedure. Modelers who do so often find that
the airplane is difficult to control, or out of control after it is
too late. Preserve your model and insure that the first flight
won’t be the last by balancing the model according to the
following instructions.
The C.G. (center of gravity) must be checked when the
model is ready to fly with the propeller and battery installed.
❏
1. Use a felt-tip pen or narrow strips of tape to mark the
balance point on the bottom of the wing 1-5/8" [41.3mm]
rearward from the leading edge of the wing on both sides of
the fuselage.
❏
2. Lift the model right-side up at the balance point you
marked on the bottom of the wing. If the nose drops, the
model is nose-heavy and you must add weight to the tail. If
the tail drops, the model is tail-heavy and you must add
weight to the nose.
❏
3. If additional weight is required to balance the model,
use small pieces of Great Planes stick-on weight
(GPMQ4485). If weight is required in the nose, do not stick
weight to the cowl. Remove the cowl and stick the weight to
the firewall. If weight is required in the tail, it can be stuck to
the top or bottom of the stab next to the fuselage.
❏
4. After placing weight on the model where necessary,
recheck the C.G. to confirm that it is correct.
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.
Be certain the transmitter batteries are fully charged. Follow
the battery charging instructions that came with your radio
control system to charge the batteries or replace if using
alkaline batteries.
Before you fly you should perform one last overall inspection
to make sure the model is truly ready to fly and that you
haven’t overlooked anything. If you are not thoroughly
familiar with the operation of R/C models, ask an
experienced modeler to perform the inspection. Check to
see that you have the radio installed correctly and that all
the controls are connected properly. The motor must also be
checked by confirming that the prop is rotating in the correct
direction and the motor sounds like it is reaching full power.
Make certain the elevator and rudder are secure, the
pushrods are connected, the controls respond in the correct
direction, radio components are securely mounted, and the
C.G. is correct.
Ground check the operational range of your radio before the
first flight of the day. With the transmitter antenna collapsed
and the receiver and transmitter on, you should be able to
walk at least 100 feet away from the model and still have
control. Have an assistant stand by your model and, while
you work the controls, tell you what the control surfaces are
doing. Repeat this test with the motor running at various
speeds with an assistant holding the model, using hand
signals to show you what is happening. If the control
surfaces do not respond correctly, do not fly! Find and
correct the problem first. Look for loose servo connections
or broken wires, corroded wires on old servo connectors,
poor solder joints in your battery pack or a defective cell, or
a damaged receiver crystal from a previous crash.
Range Check
Ground Inspection
Charge the Transmitter Batteries
Identify Your Model
Balance the Model (C.G.)
Set up the Spirit of St. Louis so it has the following
control surface throws:
ELEVATOR: 5/8" up 5/8" down
[15.9mm] [15.9mm]
RUDDER: 1-1/4" right 1-1/4" left
[31.8mm] [31.8mm]
Second to the C.G., the control throws have the greatest
effect on the way a model flies. Set the throws as close to
these settings as possible. If you have too much control
throw the model may respond too quickly. If you do not have
enough throw you may not be able to maneuver the model
or have enough control to land it when the motor is off.
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