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Patriot xl and wing rebuilding

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Old 05-13-2007, 03:08 PM
  #1  
le fou
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Default Patriot xl and wing rebuilding

Hello,

I crashed my patriot xl due to lost of orientation, could not tell the difference between the top and bottom anymore. I guess that my covering scheme was not enough different between bottom and top...
It is repairable and I am almost done with the wing. The bottom and top spars have taken some damages on the half right wing, so I cut the damaged sections and replaced them by new ones. I took some pictures and would like to have some feedback to see it it will be strong enough.

Thanks,

Le fou


The first picture shows the damaged top spar. The next three pictures show the top spar after the repair. The middle first picture is an overall picture of the top spar after the repair. The second picture of the middle row shows the damaged bottom spar. The next two pictures show the bottom spar while being repaired and after the repair. The last picture shows the bottom sheeting.
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Old 05-13-2007, 06:38 PM
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LGM Graphix
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Default RE: Patriot xl and wing rebuilding

Man, I don't think I'd trust that spar repair just as is. My suggestion would be to get some carbon fiber tow (the long strands of carbon) and run it along the spar top. It won't need to be a very thick layer, in fact, if you can find .007" x .250" carbon strips that would work as well. Glue it really well to the spar and extend at least 6" past the break. Then when you resheet it you'll just need to sand a slight recess in the sheeting over the spar so it fits flush. As it looks right now the glue joints you have are pretty filled with glue instead of a nice tight fitting joint. Glue by itself like in those gaps doesn't offer much strength. I'd definitely be reinforcing it with some carbon fiber personally.
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Old 05-13-2007, 06:57 PM
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Default RE: Patriot xl and wing rebuilding

LGM Graphix,

Do you know where I could get some carbon fiber? Either locally or via the Web?

Thanks,

Le fou
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Old 05-13-2007, 07:26 PM
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Default RE: Patriot xl and wing rebuilding

aerospace composites has everything you'll need.
www.acp-composites.com
specifically this page here I think will give you what you need http://www.acp-composites.com/acp-ucfl.htm
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Old 05-13-2007, 11:04 PM
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Default RE: Patriot xl and wing rebuilding

LGM Graphix,

Would this be O.K: CL1-31 (0.007" thick x 36" long)? Size/other indicates 1/4". I want to make sure I buy the right part.

Thanks a lot,

Le fou
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Old 05-14-2007, 02:59 AM
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Default RE: Patriot xl and wing rebuilding

even with the carbon the spar now has a very weak point, if it were further out from the center I'd say the carbon would be enough but I'd recommend you remove and replace all the spar or you'll likely be doing allot more damage very soon when it fails.

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Old 05-14-2007, 06:17 PM
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Default RE: Patriot xl and wing rebuilding

KC36330,

If I understand well, I should remove the entire spar from the wing and put a new one? Don't you think that by removing the actual spar from all the ribs, etc... I will be introducing more weak points due to what I have to do to remove it than just reinforcing the broken one?

Thanks,

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Old 05-14-2007, 07:44 PM
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Default RE: Patriot xl and wing rebuilding

Yes remove the entire spar, it takes a bit of finesse but you can do it and then replace it with a perfect fitting new spar and it'll be as strong as it originally was. now if you go about it with a sledge hammer and a blow torch it'll likely weaken it but use care and it's an easy task. use a fine toothed saw and cut the spar as close to each rib on both sides as you can and then notch the spar out with the same fine toothed saw, when you get the leading edge and trailing edge of the spar notched you can usually take pliers and 'snap' the spar out from the rib slot with no damage, then just clean it up so you get a good bond with the glue.

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Old 05-14-2007, 08:19 PM
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Default RE: Patriot xl and wing rebuilding

I would rather build another wing then replace a spar. Your pictures do not show the big picture but if it was a clean break I would glue it back together. Then some thin carbon fiber top and bottom glued on. I would then wrap it with kevlar thread and put some thin CA on it. Then while supporting the wing on the outside of the break I would apply significant pressure to see if it holds. Most crashes I have had that broke a wing were a total but that may not always be the case. Are you having to repair the leading and trailing edges also? Do you have a pic of the whole plane after the crash but before repairs were started.
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Old 05-14-2007, 09:27 PM
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Default RE: Patriot xl and wing rebuilding

the carbon is practically useless in the location of this brake, the wing isn't being stressed so much so in an up/down motion as it is front to back and twisting which the carbon does absolutely nothing at all for when you lay it on the top/bottom of the wing in the direction of the spar.

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Old 05-14-2007, 09:47 PM
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Default RE: Patriot xl and wing rebuilding

LEFOU, to each his own. I would take a 2" cut-off wheel on a die grinder and dish out the middle portion of that spar where the break is, and taper the "ditch" well past the ends of the damage. Then mix up a batch of epoxy and cram as much saturated C/F strand lengthwise into the ditch as possible. Then sheet it with medium balsa and glass over the repaired area with a layer of 2 oz cloth on the balsa skin. Once you are done, give it a good manual stress test. It looks to me like replacing that entire full depth spar would be harder than building a new wing from scratch.
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Old 05-15-2007, 04:59 AM
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Default RE: Patriot xl and wing rebuilding

LEFOU,
To those of us that type real words, what does the above quote mean?

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Old 05-15-2007, 07:23 AM
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Default RE: Patriot xl and wing rebuilding

If you want to write a book about him, I suggest you ask him directly.
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Old 05-15-2007, 08:43 PM
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Default RE: Patriot xl and wing rebuilding

Ed Smith,

Being from Canada, I thought that you would know what it means. Anyway, le fou means the crazy one in French, yes it is a real word...

Thanks,

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Old 05-15-2007, 11:38 PM
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Default RE: Patriot xl and wing rebuilding


ORIGINAL: KC36330

the carbon is practically useless in the location of this brake, the wing isn't being stressed so much so in an up/down motion as it is front to back and twisting which the carbon does absolutely nothing at all for when you lay it on the top/bottom of the wing in the direction of the spar.

kc

How do you figure it's useless? it's a main spar, the majority of the load is the up down motion (unless I'm looking at the picture totally wrong). The carbon will make that damaged area stronger than it originally was if it's bonded well. When I was flying pattern we used to make our main wing spars with 1/8" x 1/4" contest balsa with .007" x 1/4" carbon laminated to the outside surface. I never folded a wing and my Legend V that I flew, built with spars like that, had well over 2000 flights with a honeycombed wing. If your wing is twisting that much no spar will help you. He'll need to replace the shear webs but that's easy in the busted area. The shear webs and sheeting will eliminate the twisting, that main spar needs to be strong for the up/down motion.
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Old 05-16-2007, 06:56 AM
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Default RE: Patriot xl and wing rebuilding

Le fou

Thanks for the tramslation.

Ed S
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