Wing design problem

Discussion in 'Tips, Tutorials & Tools' started by lizzienewell, Aug 8, 2006.

  1. lizzienewell

    lizzienewell Member

    I'm scratching my head over this problem, so I thought I'd share it with you, not so much for sugestions as for sharing the fun of design.

    I've design warpwings for a ground effect craft. I showed it around and some of you rightly pointed out that the way the wings meet the water is wrong. WIG craft usually have anhedral wings that turn up at the end or have a sort of fin that goes up. The lowest point of the wing usually has a float on it. This same sort of float shows up hanging down from the wings of amphibious aircraft such as the Lake Buchaneer.

    I decided that I need to angle what I'm calling the pinion fans upward. This leads to a problem with the part that I call the wrist. Here is how my thought process has gone. In designing wings with movable part I had trouble making the hinges out of paper. They were coming out too floppy and fragile, so I have made the hinges out of strip styrene with wire as the hinge pins.

    The wing structure is make of two parallelograms with the stripstyren forming the leading and trailing edges. The fore to aft parts(formers) are paper laminated around the wire hingepins. Thread diagonally across the parallelograms opens and closes the wing. The angels of a triangle always add to 180 degrees. If you shorten one leg of the triangle(the rigging thread) the angles change and squews the parallelogram(wing sturcture) and the wing warps.

    Currently the pinion fan rotates on a hinge wire that goes through a plastic laminated part(the wrist). This part then attaches by two hinge to the last wing former. The place where the part has projections to fit into the hinges is already prone to breakage. Angling the pinion fans upward puts a bend in this already weak part.

    So the puzzle is how to redesign this part so that it doesn't break. To make it more complicated the skin of the wing is nylon fabric that that is sewn closed over the end of the wing former. There is just enough room between the wrist and the former to get a needle through and sew the skin. If I make the wrist out of mattboard instead of plastic and glue it to the former instead of wiring it to the hinge it wouldn't have the weak projections but I'd also have to change how the skin attaches. Design seems to get the most difficult in attaching different kinds of materials together.

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  2. Willja67

    Willja67 Member

    Well Lizzie I know you said you weren't really asking for help but I like this kind of stuff and wanted to share my idea. Also my current project has a similar wing configuration. Right now your main wing spar is sitting flat. I suggest you stand it up. Obviously this was a done quickly but hopefully it might be useful to you.


    You have the Anhedral on the inboard section and the dihedral outboard. This design will probably help prevent your wing from sagging and it still retains the mobility you require.

    Hope this helps.
  3. lizzienewell

    lizzienewell Member


    I've sure noticed the similarity to your wing formation and have been pleased to see yours working out so well. I may try turning the wing spar vertical when I go to a larger size. I built it this way to give more support to the hinges. The spar is hinged so that it folds like a bird's wing with a bends at both the elbow and the shoulder.

    I'm working on a solution. Often explaining a problem to someone else helps with finding the solution. It did in this case. It's going to have adjustable dihedral. I'll post a picture when it gets closer to done. The moving parts on Eddik's amphibious jeep gave me some ideas. I love the Internet at times like this. It's wonderful to get ideas from the amazing little jeep he build in Kalingrad.

    Thank you for the help with vocabulary, so I don't have to go around talking about thingies on the wings.

  4. lizzienewell

    lizzienewell Member

    Here is my solution--a large hinge. It looks good so far.

    I've remade the wrist out of mattboard. I've wrapped bond paper around the wrist to make it round. It fits into a sleeve on the last wing former. When it's put together the dihedral of the pinion fan will be adjustable. This is according to concept, but I was avoiding it. It's often windy when I'm taking photos and every adjustable part adds something that can be blown out of place.

    Er, I can claim the wind blowing the model around causes realistic movement of the craft in flight. I should just make sure it's headed into the wind.

    The wing former is getting laminated around the hinge wire toward the top of the picture. The sewing pin is going through the holes for the rigging; it helps with keeping the parts aligned.
    I haven't closed up the fan yet so you can see how it goes together, and the thread that keeps the plates from spreading too far.
    Nice thing about warpwings is that I can now fit a version of the model into a plastic food container and carry it around in my purse. Yeah, so what do other women carry in their purse? I then can pull out the craft at parties and talk about cardmodels to unsuspecting victims.



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  5. lizzienewell

    lizzienewell Member

    At last!

    I've gotten version 27 of my model done. Here are the adjustable dihedral wingtip. I getting really tired of sewing the stretchy part of the wing skin. I figured out how to do it with mostly machine sewing, but not until I was part way into sewing the wings and so had to keep going. Ugh! Imagine making all your clothing with tiny little stitches.

    The skin needs to stretch to follow the movement of the wings so nylon knit is the best material. The problem is that the skin collapses on the leading edge and so I've been stabilizing it with rows of stitches. You can see that I gave up on the trailing edge.

    For the next build I will do this stabilizing with a sewing machine before putting the skin on. I'll gather the lines tight.

    This version still doesn't have the landing gear either. I had the fusalage built before I designed the retractable ski.

    Oh, and the pilot is intended to look like he's twelve years old.

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