The molding of the flaperons has been just such a matter. I have had 17 years of experience with the Seahawk and then the Glass Goose building processes. One of those that I have always found the most challenging has been the making of the flaperons. The flaperons have always been produced by hot wiring blue styro-foam to the shape of the templates provided in the plans. As anyone that has accomplished this task can tell you, this process is less than easy and results in parts that are less than dimensionally perfect. The results are usually acceptable as far as functioning as flaperons, but left a lot to be desired from the stand point of ease of assembly and finishing, and accomplishing good straight surfaces and a good straight trailing edge was a very laborious and time consuming job. A truly straight trailing edge was almost impossible.

In the case of the flaperons, the part has been actually cut in 2 four foot sections that were then adhered together to make 1 eight foot long piece. This meant that there were 2 "dip" areas to try to correct. Then there was the matter of the trailing edges. Since the flaperons were covered with regular fiberglass which doesn't have a lot of stiffness, the trailing edges were a REAL challenge to get straight and to get to STAY straight. All this resulted in a lot of Micro and primer surfacer being used to accomplish the finish work and that added to the weight of the finished part. Remember that because it becomes more important than it seems it should as this explanation continues.

With the demise of our demonstrator 4 years ago due to unbalanced flaperons, the subject of the weight of the flaperons and the location of the weight in the flaperons began to be a new area of

That was unavoidable. The heavier the flaperons, the more weight it was going to take to balance them. Putting balance arms on the flaperons would detract from the esthetics of the plane and balance arms on the end of an 8 foot long and 7 inch wide control surface would subject the control surface to more torque forces than I was ready to accept.

The best way to balance any control surface is down the full length of the side that needs to be weighted. This approach imparts NO torque forces to the control surface. With a single balance arm on the outboard end of the flaperon, there is also the fact that ALL of the inertia of the balance weight will be applied to the one hinge at the end of the wing, and that point is the point subjected to the most severely amplified impact forces on the entire aircraft. On impact (like waves) the end of the wings are thrown down and then naturally spring back up. The effect is something like that of snapping a bull whip and the G forces imparted have a tremendous amplifying effect on any weight on the end of the wing.

A designer attempting to balance a control surface by adding weight down the entire length of the leading edge must be concerned about the total weight of the part but more importantly, he must be concerned about how much of that weight is aft of the hinge point. If the surface is hinged where there is just as much weight forward of the hinge pin as there is aft of it, then the surface is inherently balanced and no balance weight is required. Of course, this is a highly unlikely senario as most control surfaces are hinged as far forward as possible and most of the weight is aft of the hinges

I chose to move the hinge point aft as far as was practical to give as much moment arm as possible to the balance weight in the leading edges. In working with the geometry, of the parts and the mechanism, I found that I could make it work just fine. It was going to require more balance weight than I liked due to the short moment arm ahead of the hinge point, but it wasn’t bad considering the other choices.