ADJUST THE THROTTLE
❍
2. For added safety and convenience, the throttle should be set up
so that the engine can be stopped using the throttle trim. To do this,
loosen the screw on the Screw-Lock Pushrod Connector and move
the throttle pushrod so that the carburetor is completely closed with
the throttle stick and trim lever on the transmitter fully back. (Note:
If the carburetor does not fully close, adjust the idle stop screw on
the carburetor until it will.) Next, tighten the screw on the Screw-
Lock Pushrod Connector. Test the trim lever by advancing it to full.
This will be a fast idle position with the carburetor barrel open
slightly (about 1/32" or .8mm).
Now move the throttle stick forward to full. Make sure that the
carburetor barrel opens all the way. (See sketch.) If it doesn’t open far
enough or opens too far (bending the rod) move the Screw-Lock
Pushrod Connector in or out on the servo arm and/or the carburetor
arm to gain or reduce movement. Apply a small amount of thin CA
onto the threads of the Screw-Lock Pushrod Connector when you are
done. The throw will be correct when the carburetor barrel will stop
fully open at the same time the throttle stick reaches full. With the
throttle set up properly, you should be able to run the engine with the
trim lever set midway to the full position (adjusted for a smooth but
slow idle). Then when it is time to stop the engine, simply pull back
the trim to close the carburetor and the engine will stop running.
ADJUST THE CONTROL THROWS
❍
3. Check the movement of the control surfaces. Use a ruler to
match our measurements listed below. If your radio features dual
rates, set up both the high and low rates following the radio system’s
instructions. If your radio does not have dual rates, set up the plane
using low rates first and increase the throws as you get familiar with
the plane.
Low Rate
High Rate
Aileron
1/2" (13mm) up
5/8" (16mm) up
1/4" (6mm) down
3/8" (9.5mm) down
Elevator
3/8" (9.5mm) up
1/2" (13mm) up
3/8" (9.5mm) down
1/2" (13mm) down
Rudder
1" (25mm) left
Same as low rate
1" (25mm) right
Same as low rate
These are the suggested deflection from center of the control surface.
If you need more control movement, you should move the clevis to
a hole closer to the control surface or you can move the rod at the
servo away from the center of the servo. If you have too much
movement, do the opposite. See the following sketches:
CHECK THE LATERAL BALANCE
Special Note: Do not confuse this procedure with “checking the
C.G.” or “check the fore-aft balance.”
Now that you have the basic airframe completed, this is a good time
to balance the airplane laterally (side-to-side). Here is how to do it:
❍
1. Temporarily attach the wing and engine (with muffler) to the
fuselage using fourteen #64 rubber bands (
see page 25 for suggestions
on using rubber bands).
❍
2. With the wing level, lift the model by the engine propeller shaft
and the fin post (this may require two people). Do this several times.
❍
3. If one wing always drops when you lift the model, it means that
side is heavy. Balance the airplane by gluing weight to the other wing
tip. Note: An airplane that has been laterally balanced will track
better in loops and other maneuvers.
CHECK THE FORE-AFT BALANCE
Note: This section is VERY important and must NOT be omitted! A model
that is not properly balanced will be unstable and possibly unflyable.
❍
1. The balance point (C.G.) is located 3-3/4" [95mm] back from
the leading edge of the wing against the fuselage. Balance your Tower
Trainer using a Great Planes C.G. Machine
™
Airplane Balancer
(GPMR2400) for the most accurate results. This is the balance point at
which your model should balance for your first flights. After initial trim
3-3/4"
BALANCE YOUR MODEL
results in more throw.
Moving the clevis inward on the control horn
throw
More
throw
More
More
movement
results in more pushrod movement.
Moving the clevis outward on the servo arm
Less
movement
movement
More
Open Slightly (Idle)
Fully Open
18