Dynaflite DYFA2018 - Manual (Page 23)

The balance point (C.G. - Center of Gravity) is
located under the spar. This is the balance point
at which your model should balance for your
first flights. Later, you may wish to shift the
balance up to 3/8" behind the spar to change
the flying characteristics. Moving the C.G.
forward of the spar will add some stability but
it will decrease the overall performance of the
sailplane and make it stall easier at slower
speeds. Moving the balance behind the spar
makes the model more agile with a lighter and
snappier "feel" and improves the sailplane's
response to air currents. It also makes the
model less stable and can cause the sailplane
to "tuck under" or dive when its flying speed
increases. If you fly the Daydream with its C.G.
behind the spar (usually only contest flying),
pay close attention and do not let it gain
excessive speed. If it does tuck under and you
have plenty of altitude, give the plane a little
down elevator and allow it to go on under.
When it starts to climb up the back of the
"outside loop" its airspeed will drop and you
can pull out with some up elevator or roll out
with full rudder. If you don't have plenty of
altitude, gently pull out with up elevator but be
careful and don't "force" it up or you may
over stress the wing.
With the wing attached to the fuselage, and all
parts of the model installed (ready to fly), lift the
model by picking it up with a finger on each
bottom inner spar. If the tail drops when you lift,
the model is "tail heavy" and you must add
weight to the nose to balance. If the nose drops,
it is "nose heavy" and you must add weight to
the tail to balance.The model should hang with
a slight nose down attitude. Add lead to the
front of the fuselage to correct a tail heavy
model. Getting the weight farther back helps
correct the "nose heaviness."
This is a very important step and should
be done occasionally throughout the
flying season. A sailplane's wing is most
efficient when it is not twisted or warped at all.
"Washout" (wing trailing edges twisted up at
the tip) helps make a poor wing design fly
better by adding some stability (preventing
stalls) at slow speeds but it cuts down on the
wing efficiency at normal speeds. The
Daydream's wing is designed to fly well at slow
speeds without any washout, and therefore we
recommend you check to make sure the wings
are "flat" using the following procedure:
Set the wing so an inner panel is resting on a
flat surface. Any warp (twist) will show up by
causing a corner of the panel to rise off the
work surface.
To remove the warp, gently twist the wing in the
opposite direction while a helper glides an iron
or heat gun over the covering on both the top
and the bottom of the panel to re-shrink the
covering. Hold the twist until the covering cools
and then recheck for warps. It may take several
tries to get a warp out but it is worth it as you
will end up with a sailplane that flies straight
and true and responds to air currents like a high
performance sailplane should.
Follow the same procedure to check all four
wing panels and then go back and double check
them. Sometimes you put a warp in one panel
while trying to fix another. You should also look
at the tail surfaces as they too can warp.
2-5/8" [67mm]
23