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wing tip fix ?

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Old 03-08-2009, 10:48 PM
  #1
hudmun
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Default wing tip fix ?

the tip has a big hole in it but is perfectly atached and stong. I'm thinking i might just fill the tips with that insulation that comes in the spray can and then form it and paint. what do you guys think and what would you do. Instead of ordering a new one.
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Old 03-08-2009, 11:10 PM
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lejongleur
 
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Default RE: wing tip fix ?

I think that is a great idea. That expanding insulation/foam stuff should do the trick nicely.
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Old 03-08-2009, 11:53 PM
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Default RE: wing tip fix ?

I have had quite a few of the VQ's with the plastic wing tips and they shatter at the first touch with the ground.
After trying to patch them up I found the best solution was to take the plastic tips off altogether, and shape up some balsa tips to replace them.
There is very little weight gain (about 8grms per tip)and they are much tougher and easier to repair.

The spray foam is a good idea but it is quite heavy and tends to develop large gas pockets, so when shaping and finishing you need a lot of filler.

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Old 03-09-2009, 10:18 AM
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RC MANIAC119
 
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Default RE: wing tip fix ?

Boland is right....

the only way to do that is with a balsa block. Ton's easier to work with! Besides, that spray foam is extremely hard to work with, gets all over the place.....is VERY sticky, and keeps growing until it cures...NOT a good option!!
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Old 03-09-2009, 01:21 PM
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Default RE: wing tip fix ?

mboland,
So what's the little air compressor for? Fill the air tank on retracts?
Nice job on the tip repair, that is the far better way to fix tips, I've done the great stuff poly-urathane foam, if you don't have a place for the foam to escape while it cures, it's common to end up with a part that swells up like a bloated tick or breaks internal structure. Balsa is just too easy to work with compaired to foam and having to seal the pores and make it smooth to accept paint.
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Old 03-09-2009, 03:29 PM
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Default RE: wing tip fix ?

I did forget to mention the swelling and broken structures didn't I.
Another down side for the foam fix.
I have used used the spray foam to good effect in a couple of repairs I did where I filled the D-box with it. Very heavy, and it was a real battle to stop the bulges as it cured but the wings are as tough as nails now.

I fly mostly scale (well semi scale ARFS and only a few kits) and all have air retracts in them. So part of my field kit is a compressor.
Hope that answers your question.
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Old 03-09-2009, 03:40 PM
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Default RE: wing tip fix ?

We used the foam to support the underneath of baths in house construction. It expands and keeps expanding, you would come back in the morning and your bath would be 4" higher than you left it. You have to contain that stuff !!!!!!!!!!!!
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Old 03-09-2009, 04:28 PM
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Sig and many boating supply houses sell the 2 part expanding foam, they often include a chart to let you know how much to put in for a cubic volume desired to fill, but they always recommend putting a expansion hole opposite the pour point, that way thee excess comes out the hole and not lift the structure or break it. First time I saw someone use poly-foam to fix a wing it was comical, he injected it and about 2 minutes later it was ooozing out the hole, that point curewd and made a plug, 5 minutes later the ribs could be heard breaking free of the sheeting as it swelled up like a tick till the trailing edge poped off and it came sliming out the rear of the wing. I just sat there laughing so hard I was crying, he was too, but he wasn't laughing!
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Old 03-09-2009, 07:29 PM
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Default RE: wing tip fix ?

thanks for the advice guys, i like the idea of using solid blocks of balsa. i hadnt thought of that.
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Old 03-09-2009, 07:33 PM
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Default RE: wing tip fix ?

YOU ARE WELCOME!!
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