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Author Topic: Foam wings  (Read 1599 times)

Offline James Mills

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Foam wings
« on: April 05, 2009, 05:09:45 PM »
Would there be any benefit  laminating fiberglass between the balsa skin and ply spar and ribs around the wing gear for strength?

James
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Offline RC Storick

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Re: Foam wings
« Reply #1 on: April 05, 2009, 05:20:38 PM »
Well the benefit would be extra weight. But its not necessary in my mind. Don't build it to crash build it to fly.
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Online Brett Buck

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Re: Foam wings
« Reply #2 on: April 05, 2009, 06:41:04 PM »
Would there be any benefit  laminating fiberglass between the balsa skin and ply spar and ribs around the wing gear for strength?

    I am going to do something like that with the stabilizer on the next airplane, with graphite instead of fiberglass. I haven't decided about the wing.

     Strength is not that important but stiffness is, well worth a few ounces. Every time I make something stiffer, I get a better airplane, weight notwithstanding. As long as we have piped 75s I think that will be the case, within reason.

      Brett

Offline James Mills

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Re: Foam wings
« Reply #3 on: April 05, 2009, 07:17:40 PM »
    I am going to do something like that with the stabilizer on the next airplane, with graphite instead of fiberglass. I haven't decided about the wing.

     Strength is not that important but stiffness is, well worth a few ounces. Every time I make something stiffer, I get a better airplane, weight notwithstanding. As long as we have piped 75s I think that will be the case, within reason.

      Brett
Brett,

I'm going to ask a silly question, by graphite do you mean carbon fiber?  The main reason I would do it would be for strength in the spar and landing gear.

James

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Online Brett Buck

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Re: Foam wings
« Reply #4 on: April 05, 2009, 08:06:34 PM »
Brett,

I'm going to ask a silly question, by graphite do you mean carbon fiber?  The main reason I would do it would be for strength in the spar and landing gear.

   Yes, they are one and the same.

    There are probably more effective ways to beef up the landing gear than this. Adding a third half-rib, and putting in gussets from the spars and ribs to the landing gear block are more efficient, weight-wise.

    Brett

Offline James Mills

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Re: Foam wings
« Reply #5 on: April 05, 2009, 09:53:47 PM »
   Yes, they are one and the same.

    There are probably more effective ways to beef up the landing gear than this. Adding a third half-rib, and putting in gussets from the spars and ribs to the landing gear block are more efficient, weight-wise.

    Brett
Thanks, that's a better idea I think (I guess you engineers come up with some good stuff from time to time LL~ LL~ S?P).

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Offline RC Storick

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Re: Foam wings
« Reply #6 on: April 06, 2009, 09:00:14 AM »
Thanks, that's a better idea I think (I guess you engineers come up with some good stuff from time to time LL~ LL~ S?P).

James

Two light ply ribs one on each end have worked for 1000's of fomies. Why re invent the wheel?
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Online Brett Buck

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Re: Foam wings
« Reply #7 on: April 06, 2009, 10:33:02 AM »
Two light ply ribs one on each end have worked for 1000's of fomies. Why re invent the wheel?

    I was just answering the question, not evaluating it. If you fly over grass the "conventional" method is marginal. And they are noted for the occasional breakout - and the typical failure mode is that the ribs break or the block breaks away from the ribs . Since you have to pass the leadouts through the ribs with enough clearance to permit free motion at the extremes of travel, you can't make them a lot bigger, so you need to make more of them, or provide extra connections from the ribs to the block to spread the load.

    An airplane that is 3 grams lighter is worthless if the landing gear is broken out of it.

    Brett

Offline RC Storick

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Re: Foam wings
« Reply #8 on: April 06, 2009, 11:44:58 AM »
  An airplane that is 3 grams lighter is worthless if the landing gear is broken out of it.
    Brett

Agreed.. I guess it depends on where your flying.
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Offline Bob Reeves

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Re: Foam wings
« Reply #9 on: April 07, 2009, 10:48:36 AM »
Agreed.. I guess it depends on where your flying.

If you aren't prepaired to fly on grass in the mid south you severely limit yourself to what events you can attend.

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