has anyone used fiberglass laminates for gusset material

Discussion in 'Wood Construction' started by John wadman, Aug 17, 2019.

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  1. Aug 17, 2019 #1

    John wadman

    John wadman

    John wadman

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    I'm building stick built wing ribs and will run out of 1/16' ply to use for gussets. I have a sheet of fiberglass boat cloth that i laid up of three layers with the weave at 30 degrees and 60 degree to the first layer. Has anybody ever used or know of a plane that has used fiberglass o other composite to make gussets? I know that the late Ron Scott (EAA hall of famer) built a single seater very similar to a Tailwind years ago and used fiberglass panels bonded with epoxy to a wooden frame and the plane (old ironsides, see various issues of sportplane magazine) lasted for years.
     
  2. Aug 17, 2019 #2

    SVSUSteve

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    Wouldn’t the easier and more practical option be simply buying more plywood?
     
  3. Aug 17, 2019 #3

    John wadman

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    the closest place to buy that plywood is hundreds of miles away and becaue of size shipping costs more than the plywood so looking for suitable alternatives.
     
  4. Aug 17, 2019 #4

    Turd Ferguson

    Turd Ferguson

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    Just curious, after cure how thick was the 3 ply layup??
     
  5. Aug 17, 2019 #5

    TFF

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    It’s been discussed before. I wouldn’t. Maybe if I had some G10 sheets. Aeronca used cardboard. I would rather have some hobby ply shipped in and everything consistent. It’s a home built so anything is doable. The question is are you trying to prove something new or just lazy. I’m usually lazy and that makes those options bad choices for me.
     
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  6. Aug 17, 2019 #6

    FritzW

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    Driving staples or tiny A/C nails through the fiberglass might be a chore.

    How much 1/16" do you need to finish the gussets? Maybe use some Sig model airplane ply from the local hobby shop or Hobby Lobby.
     
  7. Aug 17, 2019 #7

    Hot Wings

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    I can't think of a reason it wouldn't/couldn't work. If the old Aeronca could use paper gussets for the ribs.......no nails there either.


    Edit: did just think of a reason it won't work:

    If T-88 is going to let your plane fall apart in the sun then the fiberglass gussets will also probably self destruct in sympathy? :p
     
  8. Aug 17, 2019 #8

    RPM314

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    As with everything you should be able to make it strong enough by throwing a sufficient amount of material at it, just do your own testing.
    Others have suggested buying hobby plywood to keep the shipping low, just to add one more source for you to compare I usually get birch ply for my models online from tower hobbies.
     
  9. Aug 17, 2019 #9

    Hephaestus

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    Carbon fiber tape gussets were once somewhat common in the RC world. Probably been 30+ years since I've seen it done...
     
  10. Aug 17, 2019 #10

    John wadman

    John wadman

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    I only measured it with my eyeball ruler but it looks to be 1/16" and is 3 or 4 layers of boat cloth. I had another layup that was three pieces of surfboard cloth and it was still flexible and thin.
     
  11. Aug 17, 2019 #11

    John wadman

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    Thanks for all of the input guys. I ended up finding 5 12' x 24' sheets of 1/32 Midwest modeling ply at Michaels crafts for about $8 pr sheet with coupons. So no worries! I'll vacuum bag two layers together and presto. The Aeroncas had cardboard gussets? Really?
     
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  12. Aug 18, 2019 #12

    Hot Wings

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    Yes, really. And they lasted for decades with no problems. The sticks under them weren't even cut to fit. Just cut at 90 degrees with no attempt to make a proper butt joint.

    But it isn't cardboard. More like thick gasket paper you get at NAPA. Called "Fish Paper" and was/is used in electric motor winding. Manufacturers can get anything certified as long as it passes the load test and it matches the drawings. ;)
     
  13. Aug 18, 2019 #13

    wsimpso1

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    It appears that the first question is finding no one that has done it.

    I do have some comments about trying the topic of this thread.

    Building ribs with fiberglass gussets is breaking new ground. You have some work to do:

    Some simple calculations will show the tensile stiffness and strength of the plywood gussets normally used, and similar tensile stiffness and strength fiberglass gusset of the same profile (but less thickness) can certainly be worked up, remembering that the wood works with a FOS of 1.5 while composite parts use FOS of 2.0. You should make sure that fiberglass gusset is at least 2/1.5 = 1.33 times as strong and as stiff in both directions compared to the classic parts.

    Since WEIGHT IS THE ENEMY, you would be well served to check if the selected fiberglass laminate is heavier than wooden counterparts, and then consider carefully if carrying any extra weight aloft is warranted...

    I would recommend:
    Vacuum bagging the gusset stock with peel ply on both sides to improve bonding;
    Sanding the faying surfaces on the fiberglass gussets with 200 grit immediately before assembly to get a good bond;
    That you can not directly staple or nail the pieces together will necessitate some other method of clamping, which may be a challenge to develop and will doubtless slow your production.

    What would I do? I would buy some more of the right plywood from Wicks and cry only once...

    Billski
     
    Last edited: Aug 18, 2019
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  14. Aug 18, 2019 #14

    SVSUSteve

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    Road trip? I am planning to do that when I have to buy stuff for my build. It’s cheaper to drive to Aircraft Spruce than to pay for shipping.
     
  15. Aug 18, 2019 #15

    wsimpso1

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    Wicks Aircraft is much closer to you.
     
  16. Aug 18, 2019 #16

    SVSUSteve

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    Never realized that. Thanks!
     
  17. Aug 18, 2019 #17

    wsimpso1

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    I have bought a huge fraction of my stuff from Wicks over the years. Good service, speedy shipping, comparable costs. Sometimes they have stuff that AS&S does not. Their catalog should be on your shelf.

    Billski
     
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  18. Aug 18, 2019 #18

    BJC

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    Wicks is a good supplier.

    However, if you get near Peachtree City, GA, stop at ACS&SCo. just to see the well-known aircraft hanging in their showroom.


    BJC
     
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  19. Aug 18, 2019 #19

    Kyle Boatright

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    Land at Falcon Field (KFFC) and walk over. When you're done shopping, walk to the other end of the field and visit the CAF wing that is based there. They have 10 or so aircraft, anything from an L-16 (Champ) to a Mustang, Dauntless, and Corsair. The inventory does change over time, so it may be different today from the last time I visited.
     
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  20. Aug 18, 2019 #20

    wsimpso1

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    You will do best to order ahead and let them (either place) know the day you plan to pick up. Oh, and know that wood cap strip sizes are almost always made to order and require a few days lead time. Also, they are not limited to those sizes - they can cut strips to your sizes.

    Billski
     
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