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For initial test flying and familiarization purposes, we suggest
a starting balance point of 27%, which is approximately 4-7/8"
behind the leading edge of the wing.
As we all know, as the balance point is moved aft, an airplane will
become more responsive in all axis, but it will be especially
noticeable to a model pilot in "pitch" (up and down). We have flown
the SUN DANCER at the 30% location and found it to be
manageable, with excellent aerobatic capabilities. However, we
did notice an increase in pitch sensitivity and had to decrease the
elevator throw to compensate. "Softening" elevator response with
a reasonable exponential percentage also works. In the end, the
final balance point and control throws you use will depend
somewhat on how you like to fly. Some pilots like their models
extremely reactive, others strive for more smoothness. The SUN
DANCER is a very capable aerobatic machine and can be tailored
to fit your style. We therefore suggest that you begin with the 27%
CG location and experiment from there.
If you need to move your balance point fore or aft slightly, the first
method you should try is to relocate your receiver battery pack.
Often times, moving your battery pack fore or aft is all you need to
do to achieve the desired balance point. If you have a super heavy
gas engine, it's not unheard of for the battery pack to end up
behind the cockpit area. Wherever the battery pack ends up, be
sure it is adequately secured to the model structure so it will not
move around in flight. If relocating your battery pack is not enough
to achieve the desired balance point, and more weight is needed,
consider using a larger (and therefore heavier) battery pack. Try
to avoid adding useless weight. If you need more weight in the
nose, try a heavier spinner or replace the light wheels with
heavier after-market wheels. If your model is nose heavy and
battery shifting does not work, you can make significant changes
in balance with stick-on lead weights.
These can be used
temporarily on the outside of the model until you've flown the
airplane sufficiently to know exactly where you like the CG and
how much weight it takes to get it there. Once that's done, the lead
weights can be placed inside the fuselage by simply removing the
elevator servos and securing the weights on the inside. With the
elevator servos back in place, the weights are hidden.
Finally, the aerobatic performance of your SUN DANCER will
benefit greatly if you balance the airplane laterally as well as fore
and aft. In other words, eliminate the "heavy wingtip" syndrome.
Lateral balancing requires that the model be suspended upside
down by two lines (use substantial size chord or fishing line). Loop
one line over the engine propeller shaft and the other line over the
tailwheel bracket. Hang the model from the ceiling or a rafter,
leveling it in side view. With the model secured in this way, observe
the wings. Ideally, they should be level, without one wing lower
than the other.
If one wing panel is lower, it means that it is
somewhat heavier than the other. When flying the model, this
imbalance can cause the model to "pull" to the heavy side,
especially in loops and up line maneuvers. To make the airplane
track true, the light wing panel needs weight at the tip to balance it
level with the other panel. Again, this can be done with stick-on
weights, which could later be hidden inside the wingtip.
FLYING YOUR SUN DANCER:
If you have carefully followed this assembly manual, you should
have no real problems in test flying your SUNDANCER. Try to
choose a calm day for the first flight. Good conditions will help in
correctly evaluating the flight performance of the model. Begin
your test flight by making sure the engine is properly set with a
reliable idle, a strong top end, and smooth transition performance.
Set your engine's high speed needle valve a little on the rich side,
so that when the airplane noses up the engine will not be over lean
and sag.
Holding up elevator, taxi the model to get a feel for how it handles
on the ground. Make sure you have positive left and right turning
ability. If not, make any adjustments needed to achieve positive
ground control. Once you are satisfied with the taxi tests, line the
model up with the centerline of the runway, nose into the wind.
Hold a little up elevator and advance the throttle smoothly - do not
throw the throttle open all at once! The airplane should roll forward
smoothly, tailwheel on the ground. As speed builds, slowly back
off the elevators and use just a little rudder, only as needed, to
maintain a straight takeoff run. The tail will come up as flying
speed is reached and a little up elevator will lift the SUN DANCER
off the ground.
Maintain a straight outbound flight path, climbing at a shallow
angle until a safe maneuvering altitude is reached. If the model
requires trim, fly it to a reasonable altitude first before trimming.
Initially, make your control inputs smooth and avoid jerking the
sticks.
At altitude, make any trim changes needed to achieve hands off,
straight and level flight. From our experience, this will take very
little trim input, if the model was assembled and balanced
properly. Once you're comfortable, make a few circuits around
the field to get the feel of the controls. The airplane should
demonstrate smooth flight characteristics without jumpiness or
over-sensitivity. At altitude, try a roll. Then try another roll to the
opposite side.
Properly trimmed, the SUN DANCER will roll
smoothly and very axially in either direction. Now try a loop. The
SUN DANCER should pull cleanly through loops, without
wandering to either side. Once you're comfortable, try knife-edge
flight. You will quickly find that the SUN DANCER has little or no
pitch/roll coupling and that it easily maintains altitude with just a
little rudder input! You will also discover that your SUN DANCER
has outstanding inverted flight characteristics.
Our prototypes
required only the smallest amount of down elevator to maintain
level inverted flight!
Assuming you're comfortable and getting used to the airplane,
take it to a safe altitude and throttle back to get a feel for the slow
flight and stall characteristics. Properly balanced and trimmed,
your SUN DANCER should demonstrate fairly sedate, no fuss stall
characteristics. Once flying speed and up elevator input is bled off,
the SUN DANCER should just drop its nose and resume flying as
speed picks up. All of this is great information to have when you
are setting up the first landing.
Landing the SUN DANCER is a pleasure. We like to keep a little
power on the engine during final approach, down to a few feet off
the ground. Back completely off the throttle once the airplane is
low to the ground with a good rate of descent established. Flair the
airplane as the ground approaches for a smooth 3-point landing
and rollout. Hard landings are not necessary, sound piloting skills
are.
The second flight should be even more fun because you have by
now inputted any required trims learned from the first flight. Before
flying again, check the airplane for anything that may have come
loose, become disconnected, etc. This is good practice and tends
to insure a long life for the model.
As you become more familiar with your SUN DANCER, you are
going to discover its ability to perform aerobatics.
The SUN
DANCER is an elegant aerobatic machine with seemingly endless