- 14 -
sunlight which causes the filament tape to deteriorate over time. In the process also cover
up the slot in the fin to minimize aerodynamic disturbances.
BALANCING
Correct fore-aft balance is achieved by adding lead to the nose of the Duck. You can use a large
fishing sinker or sinkers beaten into shape with a hammer, lead flashing (thin lead sheet)
rolled/beaten into shape, a slurry of lead shot mixed with glue, or even melt it yourself to the correct
size and shape.
For maximum effectiveness the lead should be positioned as far forward as possible but not so far
forward that it adversely affects the glider’s structural durability and/or the safety risk of impacts.
Please consult your local guidelines as to the minimum setback required for lead balance weight if
you intend to use the Duck for slope combat competitions. It’s usually 1 1/2 inches (38mm) from
the wing’s leading edge and sometimes 2” (50mm) from the nose. Measurements are taken chord-
wise (direction of flight), not at right angles to the leading edge. Even if you don’t need it to comply
with competition rules and want to keep the glider’s weight to a minimum, we still recommend
maintaining AT LEAST a 30mm (1 3/16”) buffer of foam at the leading edge, preferably a bit more.
101.
Now it’s time for the most important step in the Duck’s construction; adjusting the
glider’s centre of gravity (CG), also known as its balance point. If the glider is not
accurately balanced it will not fly well and may not even fly at all. An incorrect centre of
gravity is one of the most common causes of poor flight performance so take extra care here.
During balance adjustments your glider must have everything already installed in place
ready to fly, namely the fins and pushrods.
102.
First, check that your glider is
balanced side to side at the centre-line of
the wing. If required, you can embed a
small piece of lead (or a nail) into one of
the wingtips towards the leading edge. If
one wing half is significantly heavier than
the other the glider can have a tendency to
roll one way better than the other or
consistently drop one wing tip when stalled
(ie. one wing half is stalling prematurely).
Another sign that the wing is unbalanced
(or warped) is when there is a noticeable
difference between the left and right
elevon’s neutral trim position for straight level flight.
103.
Now the very critical fore-aft balance. The Duck has been designed to balance at
210mm (8 1/4”) back from the tip of the nose. Carefully measure this distance back from the
nose and clearly mark it with a pen on the bottom surface of the wing. Measure it again to
make sure it’s accurate.
104.
Beginners, or those who prefer a friendlier, tamer handling model, will benefit from
a CG up to 5mm further forward ie. a CG of 205mm (8 1/6”) back from the tip of the nose.
