Great Planes Reactor Biplane .61 GP/EP ARF - GPMA1023 - Manual (Page 26)

26
5-1/4"
[133mm]
RECOMMENDED STARTING BALANCE POINT
5-1/4" [133mm] FROM THE LEADING EDGE
OF THE MIDDLE OF THE TOP WING
The recommended C.G. is 5-1/4" [133mm] from the
leading edge of the middle of the top wing. This is
where you should balance the model for the fi rst fl ights.
Later, you may experiment by shifting the C.G. up to 3/4"
[19mm] forward or 3/4" [19mm] back to change the fl ying
characteristics. Moving the C.G. forward will improve the
smoothness and stability, but the model will then be less
aerobatic (which may be fi ne for less-experienced pilots).
Moving the C.G. aft makes the model more maneuverable
and aerobatic for experienced pilots. In any case, start
at the recommended balance point and do not at any
time balance the model outside the specifi ed range.
❏
2. Use your fi ne-point felt-tip pen and a straightedge to
draw approximately 7" [178mm] lines over the short lines you
marked in the previous step. Note: After balancing the model
later, the lines will easily wash off with a few paper towel
squares dampened with denatured alcohol, or you may leave
the balance lines on the wing for future reference.
❏
3. The included plywood balance stand will assist you
in balancing the model and determining how much (if any)
additional lead ballast may be required to achieve the correct
C.G. However, if you prefer not to use the stand and would
rather just balance the model with your fi ngertips, apply thin
(1/16" [1.6mm]) strips of tape over the lines so you will be
able to feel them when balancing the model later.
Mark the Balance Point (C.G.)
The balance point (C.G.) is to be marked on the bottom
of the top wing. It will be easier to do this now, before-
mounting the wing to the fuselage. This is where the
model will be balanced during fi nal setup later.
MAXIMUM
FORWARD
BALANCE LIMIT
MAXIMUM AFT
BALANCE LIMIT
RECOMMENDED
BALANCE POINT
(5-1/4" [133mm]
FROM THE LE OF
THE MIDDLE OF
THE TOP WING)
FORWARD
C.G. RANGE
TEMPLATE
4.5" [114mm]
5.25" [133mm]
6" [152mm]
❏
1. After the epoxy from mounting the top wing has hardened,
remove the top wing from the model. Use a fi ne-point felt-tip
pen to mark short lines directly on the bottom of the top wing
next to the lines on both sides of the plywood C.G. template.
The middle line is the recommended, starting balance point
and the forward and aft lines note the limits of the forward
and aft balance range.