Flap/aileron hinge fabric backing plates

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danerazz
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Flap/aileron hinge fabric backing plates

Post by danerazz »

For those using the "stock" .040 fabric backing plates, the manual has you rivet them to the outside of the fiberglass leading edge. This obviously leaves a .040 lap. How much filleting with filler is everyone using to smooth this transposition? Or are people generally doing something else to smooth this out a bit?

Also, anybody have pictures of these areas immediately before and after covering?

Thanks

Dane
Dane

Paralysis by analysis
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User GDS
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Re: Flap/aileron hinge fabric backing plates

Post by User GDS »

I used countersunk rivets, but didn't smooth that area at all. The only place I used Bondo on the airplane was to smooth the fuel tank transition and on a couple of stringer transitions that were sharp.

I have some pictures on Picasa. Unfortunately, Picasa has been improved so much and become so sharing-circle-helpful that I no longer use it. I can't post my photos anymore, but if you go there and search Highlander you should find it. It will be in the Highlander Wings album.
GDS
So Cal
Highlander #232
Rotax 912ULS, Dynon Skyview
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SheepdogRD
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Re: Flap/aileron hinge fabric backing plates

Post by SheepdogRD »

I was able to eliminate almost all of the fabric plate bumps.

The outermost hinges on the ailerons and the innermost hinges on the flaps are very near the ribs. Normally, those fabric plates would have to sit up on the ribs. Instead, I notched out the part that would go on top of the capstrip, and let them ride adjacent to it. A little epoxy holds the backs flush with the capstrips. Here’s a sample:
Fabric Plates - Aileron Hinge.jpg
The plates for the other bottom hinges are just riveted to the leading edge material. Because the fiberglass dips below the rib line, it’s possible to position the fabric plates on top of the fiberglass and still maintain the normal line of the fabric. I used rivet washers where the rivets were pulled against the fiberglass. That makes all the bottoms of the ailerons and ribs perfectly smooth. Here’s a lower control arm:
Fabric Plates - Aileron Control Lower.jpg
The top controls required a different approach. For each of those, I put a joggle in the leading edge of the fabric plate, so it rivets under the fiberglass leading edge. The trick was getting the angle of the joggle so the fabric plate maintains the normal line of the fabric. Here's a view of that:
Fabric Plates - Aileron Control Upper 1.jpg
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Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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SheepdogRD
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Re: Flap/aileron hinge fabric backing plates

Post by SheepdogRD »

As long as I was writing about the flaps and ailerons, I figured I should cover the wing fabric plates, too.

There’s not much we can do to eliminate the humps at the front wing strut attach points. They’re just going to be there, and all we can do is smooth them. But, everywhere else, the fabric plates can be hump-free.

The rear wing strut attach points were pretty simple: some fitting and trimming, and they were ready to attach. No significant bumps..

On the pulley plates, I notched the corner of each plate so it sits flush with the trailing edge, not on top of it. I put a joggle in the rest of it so it attaches to the underside of the trailing edge. Here’s one of the plates after fitting and forming, but before drilling:
Fabric Plates - Wing Pulley Bottom 1.jpg
And here it is in place, with the capstrip and trailing edge drilled and dimpled to match:
Fabric Plates - Wing Pulley Bottom 2.jpg

This keeps the fabric plate level with the trailing edge.

I did the aileron cable fabric plates on the top of the wing two ways, either of which works fine. Some time ago, I butted them to the trailing edge and made connector plates (this picture is flipped horizontally for comparison with the next image):
Fabric Plates - Wing Pulley Top - old.jpg
After I finished the other fabric plates, I decided to eliminate the connector plates and use a joggle so the plates rivet to the underside of the trailing edge on both sides of the ribs. This takes a bit less metal, requires only four rivets, and is even stronger. On the left side of the plate below, you can see that the part of the plate on the capstrip stops at the trailing edge. On either side of that, there’s a joggle so the plate fastens under the trailing edge.
Fabric Plates - Wing Pulley Top s.jpg
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Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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danerazz
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Re: Flap/aileron hinge fabric backing plates

Post by danerazz »

Great info, exactly what I was looking for guys! Thanks to both of you!
Dane

Paralysis by analysis
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User GDS
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Re: Flap/aileron hinge fabric backing plates

Post by User GDS »

This is a work of art:

Image
GDS
So Cal
Highlander #232
Rotax 912ULS, Dynon Skyview
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