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Old Nov 05, 2012, 08:34 PM
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So any advice in the coating department or do you guys only want to talk about what a non-traditional design it is?
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Old Nov 05, 2012, 08:37 PM
Wake up, feel pulse, be happy!
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United States, AK, Fairbanks
Joined Aug 2009
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Why go to all the trouble of using Lexan and all that jazz? Go buy some light cloth and stitch it over the frames like they once did for full-scale planes.

Or is that too traditional?
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Old Nov 05, 2012, 10:21 PM
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Canada, AB, Edmonton
Joined Oct 2004
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Guys, does the troll have to hit you over the head with his steel framed, canvas and lexan coated wings to get you to realize what's going on here? Good grief!
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Old Nov 06, 2012, 09:27 AM
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United States, MD, Elkton
Joined Oct 2011
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We've been stretching fabric over 13" spans between ribs on full size ,man-carrying airplanes for 100 years-that part you don't scare me with.
I have some spaces on 1/3 scale models that are 5" and they fly fine,with rag covering properly installed.

Just listen when we speak ! your steel plans are not so good.....and you're most likely wasting your time...more weight needs more power,which translates to more weight,which you don't need.
Forgetaboutit ! Use wood...
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Old Nov 06, 2012, 09:31 AM
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Report# 16

That did it for me! You ask for input,then drop a bomb....Please post a video of the crash.
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Old Nov 09, 2012, 03:08 PM
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Quote:
Originally Posted by epoxyearl View Post
We've been stretching fabric over 13" spans between ribs on full size ,man-carrying airplanes for 100 years-that part you don't scare me with.
Thank you, this is the kind of thing I was looking for.
I don't understand why you guys are acting like my wing is such a terrible idea, if it stays together in flight does it matter what the size/weight ratio is?

Sure it might be heavier than a wing with similar size made out of composite but who cares? I will make up for it with thrust.

Wings don't just spontaneously combust if they are a pound heavier than composite, or do they? Am I missing something here? Should I spill some blood to the god of flight so my plane doesnt get struck by lightning?

But I understand, the strongest human drive is to do what is familiar.

And to c4h10: the attitude of "if it worked why hasn't it been done" is crazy, if everyone had this attitude there would be no technological innovation. Also, I believe the word you are looking for is "litmus test" not "acid test", an acid test is a much different thing. Im suprised you overlooked this with your chemistry themed name.
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Old Nov 09, 2012, 04:46 PM
The Prez....... again
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United States, IA, Rockwell
Joined Jul 2011
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I've been following this thread a bit.

Wood has always been a "standard" in wing building. It has worked well for many years.

You want to try a "non traditional" material. Go for it and see what happens. If it fails, you will have learned something in the process. If it succeeds you have learned something in the process. Either way you will learn something.

ken
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Old Nov 09, 2012, 08:40 PM
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The 'Wack, BC, Canada
Joined Oct 2002
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I actually commend your desire to do something different. But you seem intent on not only doing something different but at the same time doing it badly. Namely the "spars" for the wing. They won't combust but at the first steep turn or dive pullout the unsupported thin blades will simply turn into a "concertina" and the wing will collapse or radically deform.

All it would take would be the addition of two runs of L section steel fixed to the webs you've shown. One on the top and one on the bottom to turn the poor design into a good one.

Try it for yourself to see what we mean. Take a strip of pop can metal that is flat and push from each end. Crumples pretty quickly, right? Now bend the second same size strip into an L shape and try it again. It's a LOT more stiff and resists the compression failure.
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Old Nov 09, 2012, 08:47 PM
Balsadustus Producerus
Escondido, CA USA
Joined Jan 2001
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Unfortunately, there is no way to prevent the fabric covering from sagging between the ribs, no matter how tightly it is stretched. The problem is not so much the spanwise distance of the ribs from each other but the leading and trailing edges being "lower" than the rib tops and bottoms, that causes the sag to occur.

And don't worry about the nay-sayers. Google "Fleetwings Sea Bird" for a really well-designed full-size seaplane made entirely of stainless steel...spot-welded throughout the entire airframe! I've seen it--it's a work of art.

Also, I'd advise not using actual covering fabric for full-size airplanes, as you mentioned Poly-Fiber. I'd go with one of the non-woven polyester fabrics such as sold by BP Hobbies or FAI Model supply. Don't over-shrink the covering as it might deform the structure.
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Old Nov 09, 2012, 08:54 PM
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Illinois
Joined Sep 2001
23,392 Posts
Why not have the wings machined from a billet? That will save all the extra work of covering. Then you can hit it with a quick coat of Rustoleum and be done. It'll be almost as practical.

Andy
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Old Nov 10, 2012, 02:29 AM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
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Post up the weight of the wing before you assemble it along with the rest of the airframe. If this does fail get some very good pics and see how it could be improved. That's if there is any real advantages in the end.
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Old Nov 11, 2012, 05:40 PM
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Man look how flimsy this snapped together wing is , not even brazed together yet and it held 160lbs where I stood.

You guys are right, it will probably explode mid-flight because it isnt made using traditional methods.
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Old Nov 11, 2012, 06:02 PM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
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Can you camp one rib in the vice and stand on another rib maybe three out or so? If it holds then this may just work. Is it going on a balsa fuse?
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Old Nov 12, 2012, 08:48 AM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
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Quote:
Originally Posted by nkalex View Post
Man look how flimsy this snapped together wing is , not even brazed together yet and it held 160lbs where I stood.

You guys are right, it will probably explode mid-flight because it isnt made using traditional methods.
So far so good. Keep us updated!

ken
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Old Nov 12, 2012, 12:36 PM
B for Bruce
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The 'Wack, BC, Canada
Joined Oct 2002
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Big deal.... I can balance my 200 lbs on an empty pop can with a bit of care. And it's a darn sight lighter than your steel parts.

And again you are assuming that strength in one way means that it will be strong in every way. But the structure will be loaded up in an entirely different manner when in flight and during high G turns and dive recovery than it is with you standing on one of the X's form by the rib and spar pieces.

Braze the bits together then clamp the root end in a vise and then hang bags of sand along the spar evenly. It's not uncommon for a model to need to withstand 10G's during an aggresive dive pullout. And if we can assume a 14 to 18 lb model from the size of your ribs that means each side will need to hold up pretty much 8 x 10 = 80 lbs based on a 16 lb model.
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