Copied from the manual, available online at:
http://www.greatplanes.com/manuals/g...anual-v1_1.pdf
Note: This section is VERY important and must NOT be
omitted! A model that is not properly balanced will be
unstable and possibly unflyable.
Use a felt-tip pen or a narrow strip of tape to accurately mark the balance point on the bottom of the wing near both sides of the fuselage The balance point (CG) is shown on the plan and on the PT-20 the balance point is located 3-1/2" (89mm) back from the leading edge. This is the point at which your model should balance for your first flights Later, you may experiment by shifting the balance up to 1/4" forward or back to change the flying characteristics.
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The control throws are also listed.