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ELEVATOR BALANCE : Here we go again!
It may seem that we harp on about
the elevator shape and balance, but the fact remains that the single most important parts
of the airplane are the elevators. Recently, since CP2O, we have had yet another builder
who experienced elevator flutter. It occurred at 120-130 mph and produced such a violent
shaking, that he was certain the airplane was going to come apart. It turned out that he
had extended his elevators trailing edge and found he had to add weight.
Unfortunately he added considerable weight only to the inboard, and none to
the outboard counter weight. This is a NO-NO!! It is critical that any extra weight added
to balance the elevators to 10º - 20º nose down (up to a maximum of .3 lb.) be equally
divided between the inboard and outboard. Keep your elevators light! In his case,
these elevators weighed around 5 lb. apiece, which is totally unacceptable. If yours are
over 3.9 (lt) or 3.6(rt) balanced, strip them to bare tubes and start over.
While we are on the subject of balance I want to clarify the method of measuring the 10º - 20º nose down angle. A few builders have been using the flat bottom of the elevator, which is wrong.