epp leading edge with bailing strap?

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slam
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epp leading edge with bailing strap?

Post by slam »

hat has been mentioning using bailing strap in between blue foam part of wing and the epp leading edge.

i have heard that the leading edge epp tends to rip. i assume the strap keeps the rip from getting to the blue foam.

i have found some water noodle slabs at kmart. they are 7/8" thick. since i don't have access to any other epp and i am majorly cheap i thought i would try this on my new ssc wings.

i am using two pieces of the epp stacked verticaly to get about 1 3/4" of epp leading edge.

my question is this. i plan to build the wing ala georgia gorilla...in that it will be all bidi tape. i am thinking about bidi taping the entire blue foam section, then putting on the first piece of epp, then strapping tape it, then put on the leading edge epp, and bidi tape it. am thinking that might keep the tearing down also.

any thoughts?

slam
Lou Melancon
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Post by Lou Melancon »

SLAM,
This week I stripped the two wings I used at the Nats to look at the damage. The photos are on www.georgiacombat.com.

The blue foam had cracks but the only damage to the EPP was where an engine went into the LE near the root. The wings had one span of bi-di tape root to tip. They have now been repaired and covered compeltely with bi-di with colored tape over the top.
slam
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Post by slam »

good write up lou.

i usually have problems with the fiberglass rods seperating from the foam. i have tried zipties and holes every inch. now i am hoping that the bidi over the spar might help.

when i do repairs like you mention on your site i usually cover with masking tape, then go over the masking tape with a woodpecker tool.

before it cures hard i pull off the masking tape with the expanded foam coming through the holes. makes for less sanding.

btw i really enjoyed your link to the merlin model engine. my son did too. what a craftsman.

slam
sgilkey
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Post by sgilkey »

Hey Lou, just read your wing repair write-up. Couple of suggestions:

1) Those cracks propagating forward from the TE right at the outside end of the wood block- you can really reduce that by putting a strip or two of packing tape from tip to tip along the TE, wrapped over the top and bottom of the wing

2)a hypodermic needle (large gage, #16 is good) and syringe, available at the farm supply store in the animal feed/care section quite cheaply, makes an excellent glue injector for fixing cracks, even with the tape still on teh wing. stick in the needle, squeeze until you see glue ooze out the crack. make injections every 1/2-1 inch or so. if you're cheap like me you will clean out the needle by sucking mineral spirits from a small cup into the syringe thru the needle, several times, to flush it out. it may still plug but is easily pushed out with piano wire. the syringe, don't do anything! it will get a film of glue on the plunger and barrel but as long as the tip is open it will still work fine for many cycles!
headshot
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Post by headshot »

Scott,

Good advice with the mineral spirits.

OMG!! You're cheap!!!!! Since when? Never noticed.....

(Probably reuses rubberbands from his planes also)
THend
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Post by THend »

[:p]I thought everyone re-uses their rubber bands?
Lou Melancon
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Post by Lou Melancon »

Thanks Scott those are very good tips. Would someone explain how they use the strapping material to bolster the EPP. My fuzzy logic isn't giving me a clear picture.
Hat Trick
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Post by Hat Trick »

You just glue the strip in between the blue foam and the EPP leading edge. Light tough and usually free!
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Which_way_is_up
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Post by Which_way_is_up »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hat Trick</i>
<br />You just glue the strip in between the blue foam and the EPP leading edge. Light tough and usually free!
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">


Mike, are you using this instead of fiberglass rods or do you still use a rod top and bottom?
aseaholm
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Post by aseaholm »

Roy,

I'm not Mike, a little shorter, but I think he still uses the spars top and bottom. The black material is very strong but not that stiff. Actually, the stiffness is fairly close to the higher strength foam. That probably doesn't make much sense but I believe the more similar stiffness allows the structure to absorb more energy before busting glue joints. This fact may also make it less desirable for wing spars to handle the flight loads. A flapping Sea Gull wing may be the result, tried that once, not much fun... [8D]

If you try this technique, use 3M77 to glue the strapping material in place. Gilkey did a lot of experimenting with adhesives this spring and found the 3M77 was by far the best.

Image

Image
Ben Morrow
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Post by Ben Morrow »

Guy's,
Been away a little too long. The new wing set-up by AJ here looks like a great Idea no matter who came up with it. My question is does anyone out there sell the EPP part of the leading edge alone? I have wings and the strap, if I'm looking right it's just the stuff they wrap boxes with?? That's one STRONG looking wing and would like to buy some EPP foam to work with. With the curve of the leading edge already cut if possible. Or do you guy's have a way of shaping the stuff. I no longer have a Hot Wire and most of the time got my wings from Nemish, Hat or Stan for my kits. Great pictures AJ! Shows for sure I've been away TOO DANG LONG and not keeping up with the newer, better ways of building.[:)]

Thanks All,
Ben
watchyerback
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Post by watchyerback »

Ben, try www.mindspring.com/~mnemesh this is who cuts wings in Atlanta and he might be able to help you out. The Georgia Gorilla and the (GD) Battle Axe are flown with Mike's stuff. The wing comes in 4 parts so I think he can sell you the cut EPP. You just need to let him know what wing you are flying.
Ben Morrow
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Post by Ben Morrow »

Thanks Darin,

Mikes the one who cut the wings for me toward the end of my Kitting days, so the Piranha wings he cuts now may be the very same thing still in E-203. I see he still offers the Piranha wings , so just maybe he'll have just what the doctor ordered! Thanks for the input! I'll shoot Mike a mail and see what the story is and if he can fix me up! Man , Lots have changed while I've been away! But that picture of AJ's wing looks to be VERY, VERY tough and strong!.........

Thanks Again,
Ben
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Which_way_is_up
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Post by Which_way_is_up »

AJ, thanks for the input. I really like the full vertical spar that we've used for the Smack II, Cobra and Falcon but was interested in the strapping material. Reminds me of the lexan spar used in the Tufflight planes I used to fly.
Hat Trick
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Post by Hat Trick »

Let me know if you need some EPP leading edges Ben. I'll get you set up.

Mike
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