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Old 11-24-2019, 08:48 AM
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Default Fiberglass tape hinge

Will fiberglass tape resist stretching when used as a hinge?

I have a flop wing glider and the hinge would be under a lot of stress when the wings deploy. I've tried mylar, blenderm, and even duct tape (because the adhesive is so strong). They all tend to stretch due to the force of the wings opening, so that the wing joint gets wider and wider. (The glider is a diagonal flop wing, so strong elastic is required to pull the wings open at ejection).
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Old 11-24-2019, 09:35 AM
jetlag jetlag is offline
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The fiberglass will bend 180 degrees, but it won't have any elastic ability to close the gap created by the amount of travel as the wings unfold. Not sure what you could use.
What about stretchy thin, wide elastic, attached latitudinally (along the hinge line)? One can buy it from Walmart in the sewing section. You'd have to glue securely to each side of the hinge; might even need to 'preload' the hinge material. Glue to one side, let dry. Then, stretch it slightly and glue...secure with pins and let glue on that side dry. It may be a tad thick, but should work.
You could even 'sew' a piece of elastic into place...just zigzag the stitching between the two surfaces to be mated. We used to do this with stick-built airplanes back in the day.
Or...
Use a piece about 3/4 wide and as long as the chord you need. Cut alternating flaps in the elastic and glue to the upper an lower of the two mating surfaces. We did this with stick-built control-line airplanes for their control surfaces back in the day.

Allen
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Old 11-24-2019, 09:57 AM
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What about aluminum tape that's used in the heating and air conditioning trade to seal vents? It has super adhesion, and the aluminum won't stretch.


Joe
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Old 11-24-2019, 10:23 AM
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Kevlar can be used as a flexible hinge, but you definitely would want to keep any attaching resin away from the hinge joint. It would go from flexible to useless if any resin got in the joint.
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Old 11-24-2019, 01:30 PM
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My go-to tape for hinges on small RC models is Scotch Multi-Task. But I don't think it would adhere well enough to what appears to be a stained or dyed balsa surface. In looking at the pictures my first thought is an old fashioned sewn hinge.

Another possibility I've seen used with mixed results is strips of Tyvek. There the trick would be much as GH describes for using Kevlar cloth: keeping the glue out of the actual joint but at the same time adhering the strip close enough to the edges of the pieces that they stay aligned properly.
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Old 11-24-2019, 01:44 PM
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My go to stuff for hinges is Dr. Shrink tape. It's an all plastic tape and has tremendous adhesion (you practically get a hernia unrolling it.) It CANNOT be torn--it has to be cut with a blade.

It's commercial use is to wrap boats and airplanes in white shrink film for seasonal storage or transport.
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Old 11-24-2019, 06:28 PM
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Quote:
Originally Posted by jetlag
The fiberglass will bend 180 degrees, but it won't have any elastic ability to close the gap created by the amount of travel as the wings unfold. Not sure what you could use.
What about stretchy thin, wide elastic, attached latitudinally (along the hinge line)? One can buy it from Walmart in the sewing section. You'd have to glue securely to each side of the hinge; might even need to 'preload' the hinge material. Glue to one side, let dry. Then, stretch it slightly and glue...secure with pins and let glue on that side dry. It may be a tad thick, but should work.
You could even 'sew' a piece of elastic into place...just zigzag the stitching between the two surfaces to be mated. We used to do this with stick-built airplanes back in the day.
Or...
Use a piece about 3/4 wide and as long as the chord you need. Cut alternating flaps in the elastic and glue to the upper an lower of the two mating surfaces. We did this with stick-built control-line airplanes for their control surfaces back in the day.

Allen


Actually I don't want any stretch in the hinge material. The problem I'm having is that the hinge materials I've tried tend to stretch too much, so that the joint begins to loosen and open up wider and wider. If fiberglass tape will bend back on itself but not stretch, it sounds like a good candidate.
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Old 11-24-2019, 06:32 PM
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Quote:
Originally Posted by mojo1986
What about aluminum tape that's used in the heating and air conditioning trade to seal vents? It has super adhesion, and the aluminum won't stretch.


Joe


I think I actually have some of that stuff. If it doesn't stretch it sounds like another really good candidate!
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Old 11-24-2019, 06:38 PM
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Quote:
Originally Posted by ghrocketman
Kevlar can be used as a flexible hinge, but you definitely would want to keep any attaching resin away from the hinge joint. It would go from flexible to useless if any resin got in the joint.

Will kevlar cloth stretch? If it doesn't than it might also be a good choice as hinge material. Do I use some kind of epoxy to glue it down?
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Old 11-24-2019, 06:58 PM
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Kevlar cloth shouldn't stretch, but being a woven material, it may not be as dimensionally stable as the aluminum tape. You could always try it. Epoxy should do a good job of sticking it down as long as you work it into the weave.

I have some of the aluminum tape and can mail you a sample if interested.


Joe
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