Total build time: 486 hours.
The ailerons must be balanced for 2 reasons: control feel, and flutter. The plans for the aerobatic ailerons call for both ailerons to be balanced to each other by hanging them by their hinge point and comparing the trailing edges. The lead counterweight is the ballast that provides the balancing, and will have material drilled away if necessary to balance the ailerons with each other.
In order to rig my ailerons for this balancing, I hanged 4 ratchet straps from the ceiling trusses in my basement.
I then made 4 loops of kite string, and inserted piano hinge wire into the hinges on both ailerons. With the kite strings spaced approximately equidistant from the center of gravity of the ailerons, this provided even and free pivot points for the ailerons to freely hang. I then spent a lot of time levelling the tops of the ailerons to each other, to make the tops even on a level plane. There was a lot of swaying in this arrangement and I had to be very patient.
I placed my padded checkerboard flooring below the ailerons… safety first!
Once I had the tops of the ailerons all levelled up, something interesting appeared…. I could not tell a difference in the trailing edges of each aileron relative to the other (a good thing). So I placed a chair, some spacers, shims, and finally the level on top to get as close as I could to the bottoms of the ailerons to detect any difference between them.
I still could not detect any difference! I sent these pictures to Sonex and they confirmed my assessment… these ailerons are already balanced. And I didn’t even need to drill any more lead! A fantastic result. It’s really satisfying that my work on each aileron resulted in no discernible difference in the balance between them.
I even hanged a small nut on a piece of string on the end of the counterweight to show how this small change in weight will slightly throw the ailerons off balance with each other.
It’s minor, but you can see in the above picture that the nut has made the left-side aileron move higher, and thus slightly out of balance with the right-side. This again confirms that no more adjustments are needed to balance the ailerons.