Balancing Your Aircraft
Balancing your aircraft (setting the center of gravity) is extremely
important for your model to fly properly. Most high wing trainers are
relatively simple to balance. Here is how to do it.
Balancing Your
Aircraft
Balancing the aircraft (setting the center of gravity) is extremely important
for your model to fly properly.
Most high wing trainers are relatively simple to balance:
Measure from the leading edge back the distance indicated on the plans
approximately 3 inches out from the fuselage on each side, mark with a
grease pencil.
Place a 1/2 inch long piece of electrical tape from the grease pencil mark
forward on the underside of the wing. With the fuel tank empty and
everything else all set up for flight balance by placing 1 finger on each piece
of electrical tape. If the nose points down slightly with your fingers on the
tape it will be within the acceptable CG range. If it balances with the tail
down and your fingers are on the back edge of the tape... (you can feel the
edge is why the tape is there) then add nose weight.
If you do some test balancing during installation of the radio equipment and
engine, you can usually move things around and not need to add dead weight
ballast. The radio system doesn't always have to be placed exactly as shown
on the plans. Moving the servos forward, or trading location of the battery
and receiver can make a large difference in the aircraft's balance point.
One balancing trick that is very good for eliminating the addition of ballast is
to delay drilling the motor mounts until the rest of the aircraft is completed.
Hold the engine on with a rubber band and balance the plane, shifting the
engine on the mount to find the best location. You can compensate more
with engine placement than by adding 1/2 oz of lead under the fuel tank on
some models.
When all else fails, then add lead weights to achieve proper balance. The
further the weight is from the CG... the more effect it has, so placing it as
far forward or back as possible helps reduce how much you have to use.
(Lighter planes fly better.)
After the fore and aft CG is corrected... hold the aircraft by the spinner and
a string looped under the bottom of the rudder. If the plane wants to flip
upside down, turn it over and do the test upside down.
Whichever wing drops is the heavy side. (if you can feel the engine
compression , rotate the prop slightly to relive this force acting on the test)
Add weight to the light wing. Drilling pilot holes and putting wood screws in
the wing tips is an acceptable and easy way to balance a trainer laterally.
The more accurately balanced the aircraft is, the easier it will be to keep in
straight and level flight.
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