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Aileron Hinge Placement

We have heard favourable comments about a technique for positioning the aileron hinges suggested by a US builder on his "Unofficial Unauthorized Challenger Page" (no longer on the net) - here it is for you to consider:

This is the most critical part of building the wing. To start, you must have either a wing building table or a large, flat, clear area (like a basketball court).

The wing building table can be four feet wide and sixteen feet long. This is fortunate. Those are the exact dimensions of two sheets of particle board. Don't use plywood, as it is too expensive and can warp. Particle board is flatter than most plywoods, and it's cheaper. It also absorbs water and swells, so build your wings as soon as you finish the table!

Other that those comments, the details of building a wing table are up to you. If you don't know how to put together a large, flat table, then get a friend to help. If you don't have friends, then your airplane will take a very long time to build, indeed.

The wing must be rigged (aligned) correctly in order for the plane to have good static stability. That means that you'll be able to let go of the stick every now and then without doing a barrel roll. The ailerons must be:

Straight. Identical. Looking at the Quad City instructions, it's easy to see to get very confused. The ailerons really should be aligned with the wings PRIOR to covering. If you try to hold the hinges in place with tape while drilling, you'll end up dejected, drunk, and a sour old man of no use to society.

The top surface of the aileron should be ALMOST FLUSH with the top surface of the wing (Section 2, Figure 8a). If you try to do this by laying the wing upside down, you'll never get the hinges drilled! It's much easier to do it this way...

The centerline of the aileron should be aligned about 1/8" above the centerline of the wing. To find the centerline of aileron, lay it down on the wing building table. The trailing edge needs to be elevated 3/8" along its entire length. Lightly clamp the trailing edge onto scrap stock at three or four places. This will ensure that the centerline of the aileron is parallel to the wing building table.

Lay a metal square flat against the leading edge of the aileron, perpendicular to the table. Lightly scrape the square against the leading edge to scribe lines where the hinges will be located. Make the lines about 6-8" longer than they have to be.

Repeat for the other aileron, and then put them aside.

Lay a wing right-side up on the building table. It's easier to find the 1/8"+ line than to find the centerline and measure the difference. Make a marking tool out of a short length of 1" square tube stock. DON'T USE WOOD FOR THIS! Go to the hardware store and get some METAL!

Now rivet a piece of 1/16" straight metal strap onto the top of the square stock, so that the strap sticks out over one corner about 1/4". When laid on the wing building table and held against the trailing edge of the wing, this overhang will exactly touch the 1/8"+ point above the wing spar centerline. Using this tool, make pencil lines where the aileron hinges will go.

Before going on to the next wing, you need to finish the first one. Ensure that the lines you marked on the ailerons match the ones you made on the wing trailing edge. Now you have to temporarily attach the hinges.

This is easy. Using large screw clamps (about $1 apiece from a plumbing store), cinch the hinges down onto the trailing edge of the wing. Use as many clamps as will fit in each hinge (they thread through the open spaces very well). The center of the hinge should line up with the 1/8"+ line on the trailing edge. Having trouble finding it? Just support the hinge with the tool you made earlier!

When each hinge is aligned properly, tighten the clamps as hard as they will go. This will deform the hinges so that they round out to fit the wing.

Now attach the other side of the hinge to the aileron leading edge, without tightening the clamps too much. Adjust the aileron so that you can barely see the leading edge centerline below the center of the hinge. Then tighten the clamps to deform these hinges.

Hang the aileron off the edge of the table and test it. It should move smoothly (yes, it will make some noise). It should not bind.

Drill each hinge between the clamps. Since the clamps will alternate on each side of the hinges, your rivets will not collide. Hold the hinges in place with ALUMINUM RIVETS. When you're finished, remove the clamps and test your aileron.

Drill out the aluminum rivets. Mark the underside of each hinge with the wing side (PORT/STBD) and hinge number (1-4).

Repeat for the other wing. Put the hinges somewhere safe for use later.


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