Chapter 19: Ailerons

Lessons Learned

  1. Look closely at Figure 46 before cutting the ailerons.  First, the inboard and outboard aileron cuts are made perpendicular to the trailing edge, but the measurement is made on the diagonals where the foam blocks were joined.  Also, you note that the outboard measurement is not made at the end of the aileron, but is made 12 inches from the end.  If you miss these salient details, you'll end up with slightly wider ailerons.  If you make these mistakes, don't worry - your ailerons will work just fine.  You'll just be doing a little extra work getting the contour of the spar cap trough correct.  It helps to read the archives.  I knew about this beforehand and avoided the errors.

  2. As I marked out the cut lines for the ailerons, I took the time to draw in the lines for the hinges on the wings and ailerons.  I temporarily fastened a straight-edge on the lines, and cut very carefully with my dremel tool.   I cut my ailerons to the length specified in the plans and resisted the temptation to make them 6 inches longer.

  3. Removing the peel ply from the aileron spar area ripped out lots of foam, just like on the wing trailing edge.  So I used pour foam, filled the holes, and reshaped the spar area.  I was more careful on the second wing to scribe the foam a little wider than the peel ply.

  4. Themís tight quarters in that aileron spar area.  So to make it easier on myself, I laid up all three BID plies onto plastic, then transferred the layup into the spar area.  Worked great.  I extended the layups into the wing the required half inch, but I did not attempt to take those layups to the trailing edge.  I made another triangular pattern and glassed the rest of the foam separately, being careful of to overlap those layups onto the 3-BID spar layup.

  5. Nat issued a mandatory change to add an additional layer of BID to strengthen the hinge areas in the aileron spars.  I went one step better and used two plies of carbon fiber.  This adds mucho strength over BID alone.  By the way, Natís mandatory change helps to decrease the chances of aileron lockup.  If you donít know the story, several Long EZ drivers had their ailerons lock up while doing high-G turns.  The hinge area deflects slightly and causes the aileron counterweight to become lodged over the lower lip of the aileron spar, thus locking the plane into a turn.  I suggest you read the back issue of the Central States Newsletter.  Very scary stuff. 


  1. If you want silky smooth controls, it is vitally important to ensure that the hinges are aligned perfectly.  The first step is ensuring that those A2 and A5 brackets get micro'd onto the aileron cores perfectly flat and in plane with one another.  I did this with the help of a length of aluminum angle.  I marked where the brackets should go, then tacked the brackets onto the aluminum angle with dabs of 5-minute glue.  I also tacked the A10 tube to the A5 bracket.  I next buttered up the depressions in the foam with a wet micro mix, being careful to completely fill the slot between the aileron skins and the foam.  You definitely don't want any voids there because you need the micro to completely fill the holes in the brackets to provide the "teeth" to anchor those brackets firmly and forever in place.  (I personally wonder why we aren't told to use flox...)   Going with the "teeth" theory, I filled the bracket holes with a drier micro mix, and then lightly brushed the brackets with epoxy/slurry.  I picked up the whole assembly and plopped the brackets and A10 tube into the correct locations in the foam.  Of course, I held all this in place with drywall screws.

  2. I ordered some spherical aileron bearings from JD Newman (Infinity Aerospace).  Very Nice!   JD provides very explicit and very professional instructions, so there's no guesswork.  The bearings are also held in place with "Clickbonds", which are essentially threaded studs with a base attachment area.  These can be used in lieu of screws.  JD uses these clickbonds to fasten the ailerons and rudders to the Infinity 1 to eliminate all screw heads.  I might explore using clickbonds on the Cozy.

  3. In retrospect, it might have been easier to fill-n-sand the entire wing first before cutting out and finishing the ailerons.  I can see where this could result in better matching and better cosmetics between the wings and the ailerons.  I was impatient and wanted more moving parts now!

Getting the Hinges to Bond to the Ailerons

Chapter 19, Step 10 (page 19-9) outlines  the procedure for attaching the wiggly things (ailerons) to the wings.  It's rather vague in that the plans say simply to apply bondo to the aft hinge halves and place the ailerons into position on the wings.  Wow, if it were only that simple!  At issue is how to hold the aft hinge pieces flush against the ailerons while the bondo cures.  With the aileron in place, you can't get to the hinges, and the hinges are not gonna just jump up and attach themselves to the ailerons!  It's clear that the builder is left to his/her own accord to devise a clever method.  The archives suggest several tricks for pressing and holding the hinges to the ailerons -- things like tape, sponges, springs, and toothpicks.

I'd like to add one more -- hacksaw blades!  As it turns out, a hacksaw blade fits perfectly between the hinge joints.  Sticking the blade into the hinge joint and using the springiness of the blade will pop the hinge into place cause it to adhere flush against the aileron. Here's the process: 

  1. Set the wing leading edge down and trailing edge up. (I have cradles)

  2. Set up whatever Rube Goldberg apparatus you need to position and hold the aileron into place during the bondoing/5-minute gluing step later. My set-up (pictured below)  included clamps and popsicle sticks for holding the aileron trailing edge to match the wing trailing edges, and some popsicle sticks between the wing and aileron top and bottom surfaces to ensure the skins matched.   Trial fit, and when happy, remove the aileron.  

  3. Cleco the hinges onto the wing trailing edge. The plans say to use screws and nutplates, but clecos are more convenient especially for removing
    the hinges from the wings without disturbing their positions on the ailerons.

  4. Slide a hacksaw blade between the hinge joints and insert it about a half inch under the opposing hinge piece (the piece that will attach to the aileron). You'll know you've done this correctly because the opposing hinge piece will go from hanging to horizontal.


  1. Put a few dabs of 5-minute glue onto the opposing hinge pieces. (I used 5-minute glue instead of bondo because the glue is more fluid, and the spring action of the hacksaw blades compresses the glue better than the bondo.)

  2. Work quickly and set the aileron into place. The hinges will be depressed as you do this and the hacksaw blades will rotate upward as the aileron is lowered into the wing. Eventually, the blades will stop rotating and will begin to apply pressure to hold the hinge pieces flush onto the ailerons. 

  1. You can overdo the hacksaw blade thing. If you slide too much of the blade under the hinge, the spring force may be too great and cause the aileron to bend (especially at the middle hinge). If this occurs, simply pull some of the blade out. 

  2. Wait for the glue or bondo to cure. Remove the clecos. Remove the Rube Goldberg stuff. Drill the hinges. 

Attaching the Ailerons to the Wings

I originally used Clickbonds to attach the ailerons to the wings.  But, while contouring the wings in Chapter 25, I found out that I was down to the glass at the hinges and could not cover the clickbonds without creating a bump.  I was unwilling to have bumps there, so I removed the Clickbonds.  I will now attach the ailerons to the wings using screws as per plans.  I found out about Clickbonds too late in the process.  Else, I could have locally recessed the foam prior to glassing -- enough to completely hide them.  Too bad because clickbonds would have been a slick cosmetic solution.  A Clickbond is a screw with a wide thin base instead of a screw head.  The bases are wide enough that tear-out (like what happens to countersunk screw heads) is not an issue.  If you do it right, you end up with no visible screw heads sticking above the wing surfaces.  A very clean installation.  What you do is drill the holes through the wing's spar box area and through the aileron forward hinge halves as per plans.  (The aft hinges are pop-riveted to the ailerons as per plans.)  Flox the Clickbonds in place.  You might think about installing a very small rivet into each Clickbond to ensure they don't turn.  Apply 1 layer of BID over the Clickbonds and onto the surrounding surface (1-inch overlap) to complete the installation. 


I've left the pictures here for posterity.  Hopefully others can benefit from them.




BTW, you don't have to worry about the Clickbonds coming off.  When I realized I needed to remove them, they wouldn't come off easily.  After sanding off the layer of BID, I had to heat up each clickbond with a soldering gun until the flox melted enough to let go!



Aileron Controls in Wing Root

  1. I finally got around to installing the aileron bell cranks, push tubes, and rod ends that go into the wing roots.  Be careful to read Chapter 16 before doing this section of the plans.  The materials and some of the detailed assembly are specified in Chapter 16 (Controls).

  1. Did you have trouble fitting the aileron crank tube through the steel aileron spherical bearings you bought from Infinity Aerospace or Ken Miller?  That's because the Brock part is cadmium-plated.  The plating, which is there for corrosion resistance, is just thick enough to prevent the tube from sliding freely into the bearing.  Instead of laboriously sanding off all the cadmium plating,  I  used my dremel tool and its small sanding drum to effectively hone out the spherical bearing to the right diameter.  The sanding drum is only very-slightly-larger than the diameter of the spherical bearing.  Honing out the bearing was faster than laboriously sanding off the cadmium plating.  Took all of two minutes to get a perfect fit.  Plus I retained most of the cadmium plating to ensure the crank tube won't rust.

  2. In step 19-11, don't drill the holes for the CS127 brackets until you check the clearance between the bell crank and the wing rib.  Per the plans, the locations for the CS127 brackets were too far outboard, thus causing the BC4W10 bell crank to hit the wing rib.  (Maybe I didn't carve my wing root deep enough in step 19-9?)   The plans call for 3/8th in clearance between the bell crank and the wing root.  So I held a 3/8th-inch piece of foam against the wing rib and moved the CS127 brackets inboard until the bell crank could be rotated without hitting the foam.  I then marked and drilled the four holes for the brackets.    

  3. Chapter 16 specifies the CS 129 push tube to be 8.7 inches long.  Don't be surprised when you compare that length to the full sized drawings on pages 19-15 (view O-O) and 19-16 (view G-G).  None of them match!  I just went with the 8.7-inch length and let the CS1A inserts hang out a bit.  To figure this out, I mounted the CS 129 push tube between the bell crank BC4W10 and the aileron crank CS132R.  I centered the bell crank and made sure the aileron crank was vertical.  I moved the CS 129 tube until equal amount of the CS1A inserts were showing.  I taped the inserts so they wouldn't move, removed the push tube, and drilled the holes through for the rivets.

[Previous] [Home] [Next]