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CRASH Crease reduction

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Old 09-07-2004, 09:49 AM
  #1  
orion1210
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Default CRASH Crease reduction

Hi guys,

Recently put my Baudis Quick Speed 400 pylon racer in wing tip first due to a duff launch on my part!!

Anyway, it created a chordwise crease/depression near the tip on the underside of the wing. No cracks are evident and the spar is not damaged.
The wing skins are a glass/balsa/glass sandwich constructiuon.

Does anybody no any way of reducing the depression as the model relies on the smoothness of the skin.

Many thanks in advance
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Old 09-07-2004, 11:31 AM
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davidfee
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Default RE: CRASH Crease reduction

Is the glass skin fractured, or just dented?

What I have normally done for things like that is to take a very thin straight pin or sharp #11 X-Acto blade and use it to pull up the skin where it has been pushed in. If the skin is not broken, you can poke holes using the pin. These holes will come in handy... just hang on. Using the pin to hold the skin in position, carefully wick thin CA into the crack/holes using the applicator tube (if available). Once the CA has kicked off, move to the next section and continue until the area is stabilized. If the skin was badly torn, you may add some light glass (25g/m^2 or .075oz/yd^2) over the area. Otherwise, just lightly sand and then apply spot putty to blend the area in. I use "white putty" from Squadron. ( http://www.squadron.com/ItemDetails.asp?item=SQ9060 )

good luck,
-David
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Old 09-07-2004, 12:23 PM
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Ed Smith
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Default RE: CRASH Crease reduction

This may not be appropriate for a small speed 400 wing but I have repaired molded wings using this method. Drill a small hole in the skin and give the hollow wing a quick shot of that expanding insulation foam. By quick shot I mean about 1/2 second. To prevent the wing from swelling up I clamp two pieces of say 1/8 balsa top and bottom to hold the airfoil shape. Use the low expansion foam.

On my larger 7/8 thick hollow wings it works quite well.

Ed S
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Old 09-07-2004, 03:02 PM
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daven
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Default RE: CRASH Crease reduction

Ed,

Your gutsy to use that expanding foam stuff. Just gotta be carefull that you don't use too much, also some of them seem to expand more when sitting out in the hot sun.

I'd use the pin and ca method myself.
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Old 09-08-2004, 07:38 AM
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Ed Smith
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Default RE: CRASH Crease reduction

Your gutsy to use that expanding foam stuff. Just gotta be carefull that you don't use too much, also some of them seem to expand more when sitting out in the hot sun.
Dave,
I had nothing to lose. The landing plate and the wing skin around it was all mushy. I drilled a hole through the plate and gave it a shot. I did clamp some wood top and bottom of the wing to prevent swelling. It worked well. The repair stood up very well, until I hit a tree that is.

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