Best fiberglass to reinforce "barn door" sized fins

Discussion in 'High Power Rocketry (HPR)' started by loopy, Nov 28, 2018.

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  1. Nov 28, 2018 #1

    loopy

    loopy

    loopy

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    Hey guys - so, I'm building a 7.5x upscale of the Estes Echo, and anyone familiar with this model will know that the fins on this thing are...well...in this scale, they are quite large. Root edge is about 12" long with a span of around 14-15". Clearly, I'm going to be fiberglassing them to reinforce them and keep them from fluttering to smithereens on launch. The question is, what kind of fiberglass should I use, and where should I get it from? I've never 'glassed fins before (never needed to), and I don't know the best way to go about this.

    Also, what is the best way to do this? tip to tip, or 'glass them before putting them on the rocket? I was thinking of doing one layer prior to installing, then another layer tip to tip because I could put a lot more weight on them for that first layer.

    Thoughts?
     
  2. Nov 29, 2018 #2

    djs

    djs

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    loopy likes this.
  3. Dec 4, 2018 #3

    David Schwantz

    David Schwantz

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    Resin will only add weight and not strength. Might think about glassing a carbon rod as LE and TE parts. Lighter and stronger.
     
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  4. Dec 6, 2018 #4

    farsidius

    farsidius

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    In addition to reinforcing fins with fiberglass, you may also consider reinforcing your root junction with something stronger like Kevlar. On my 6" Black Brant II (which also has fairly large fins), I used a strip of 4" or 6" Kevlar at the body tube/fin root junction, then overlaid that with a couple layers of fiberglass, first 6oz, then 4oz.
     
  5. Dec 6, 2018 #5

    RocketFeller

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    Our upscale Dragonfly has some fairly extreme fin dimensions, ~12" root and ~28" length. To maximize stiffness and minimize flutter we probably went overkill, I think that we could have gotten by with a few layers of CF twill instead of the plate, but the plate was easy to build/finish.
     

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