Hi All,

First time post!....I'm just about to cover my first trainer and read in a book that you can use the covering material (Ultracote/profilm etc) to hinge the control surfaces?? Is this advisable? Has anyone tried this and if so is the joint strong?

Many thanks,

Rich.

If you make S hinges with the covering they will be almost bulletproof. With S hinges, the force the hinge sees is as little as can be found on any hinge. And they can't bind or be out of true.

S hinges have been around since day one, and I'm sure that when Monokote first reared it's shiny head, a bunch of modelers tried it as S hinges. Some also tried it "the other way". The other way isn't as easy to do. Nor as inherently strong. And isn't self aligning. But also works after you learn how to do it properly. The other way used to be illustrated in the Monokote instructions.

Here's how it's done:

Much obliged guys - Thanks!!

Rich.

Minn,
Can this be done the entire length of the surfaces to cover the gap?
What would you recommend the widest each hinge be?
Thanks,
KW_Counter

It can. And the width is sort of relative. If it's a small plane or Park Flier, they may need to be only 1/4" or less. For a 40 -60 size plane, I'd say 3/8" - 1/2" Keep in mind that you need at LEAST 2 strips side-by-side (3 would be better as in the illustration above) and there is no reason why you couldn't do it the entire length.

Minn,
Is there any reason why you shouldn't use bigger pieces of covering to make the hinge? I mean, could you just make 3 big "s" hinges that were 1' wide or so and hinge the whole aileron that way? I say this, because it seems like it would take a long long time to hinge an antire surface with tiny 1/2 inch strips.

Minn is offline at the moment so I'll answer if that's ok.

There is a reason to have shorter rather than longer pieces. Long pieces can allow the force on the movable surface to displace the surface and cause a bind. Each location where the pieces change over helps to give the surface some support. That is why Minn suggested that 3 pieces per side was good. You need the "gaps" to hold the surface in line with the wing. A gap is actually a pair of pieces, and it's the pair working together that hold the movable surface where it needs to be.

What you need minimum is to have a gap near the tip of the hinge line and a gap near the root of the hinge line. It's good to have at least one more gap. I've used as few as 4 pieces to a hinge line. I'll use very short pieces at either end, and longer ones in between.

Suppose you were to use only two pieces for one strip aileron. The only place where the aileron would want to stay close to the wing would be at the gap between those two pieces. Outboard of that gap, the aileron could be pushed away from the wing when aero forces acted on it from one side. Inboard of that gap, the aileron along the other piece could be pushed away when aero forces from the other direction acted upon it. If you use a short piece near the tip, the gap between the short piece and a piece close to it will hold the aileron to the wing whichever way the aileron deflects. Same deal near the root. What's left? Between those two short pieces...... Two strips between will have a gap between them that'll hold the aileron good enough.

All the strips keep the aileron from moving aft. The "gaps" keep the aileron from moving up/down behind the wing.

hope that's clear enough...... I'll be back with a picture in a minute.

BTW, it really doesn't take a long time to do any surface no matter the number of pieces.

I usually tape the aileron to the wing to start. That way, I'm guaranteed of the alignment. Then I slip one of the short end pieces in place and iron it. Place the next piece to that one and iron it and that end of the aileron will stay in alignment without tape. I usually go to the other end and repeat. If I do a couple near the middle at that time, the tape is no longer needed. From that point on, it's as fast as you can go.

OK, here's the picture.

Each gap is where two pieces work together. They work to keep the aileron from slipping up or down behind the center of the trailing edge of the wing. Enough of them will insure that the aileron stays where it should when the aileron is buffeted by the airflow, and especially when it's deflected.

hope this helps