CENTER OF GRAVITY:
Establishing the Center of Gravity (C.G.) for this or any R/C model
aircraft is critical to its ultimate success in the air. And determining
the proper C.G. location becomes even more important with
15
smaller models. While the Bf-109 is a solid, predictable airplane to
fly, it is, none-the-less, a warbird type aircraft and is less tolerant to
improper C.G. locations than other model types.
Start by installing the battery pack that you will be using to power
the airplane. Slide the pack as far forward in the battery tray as
possible and secure it in this position to keep it from shifting while
you are working with the model. Attach the cockpit/hatch over the
battery compartment.
The correct C.G. location for this model is exactly 2-1/2" (63.5 mm)
behind the leading edge, at the fuselage/wing location. Use two
pieces of masking tape, applied onto each side of the top surface
of the wing, where it meets the fuselage wing saddle. Bolt the wing
in place to the fuselage and use a ruler to measure and mark the
2-1/2" location onto the tape, immediately next to the fuselage.
With the airplane now assembled with the battery pack in place, it
is ready for balancing. The best way to do this is to place the model
onto a balancing fixture upside down. Locate the balancing fixture
at the two 2-1/2" marks on each side of the wing, next to the
fuselage sides.
If the model is properly balanced, it will be
suspended perfectly level. If the nose hangs down, the airplane is
nose heavy and conversely, if the tail hangs down, the model is tail
heavy. A slightly nose heavy model is certainly the lesser of two
evils. However, a tail heavy condition must be remedied before
flying the airplane.
If your model balances a little nose heavy, the battery pack can be
shifted a little aft to correct the problem. If the model balances in
a tail heavy condition, then, it is likely necessary to modify the
existing battery tray, allowing the flight battery to be shifted even
further forward.
As shown with our Himax 400 watt motor
installation, we were able to modify the battery tray, allowing the
battery pack to slide a full 1-1/4" further forward.
Modeler’s Note: A standard 2-3/4" dia. yellow nylon spinner,
such as a SIG # SIGSP2755, can be used to make a nice
looking alternative spinner, by simply cutting off 1/2" from the tip
of the spinner cone.
Once this cut has been made, the cut line should be rounded
off, giving the appearance of the scale opening for the cannon
muzzle. To do this, we used a bolt and a nut as an arbor and
then, installed the end of the bolt in a drill press. With the
spinner turning, sandpaper was used to uniformly and neatly
round off the opening.
The finished spinner should look like the photo.