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Old Mar 05, 2013, 12:38 AM
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x2 3.8 tip repair log

OK so having been the victim of the New and improved Dr death at the SWC I have some repairs to consider.

Mr Reid helped me out with some tip material from his 3.8 x2 that sadly met its end in a tree so I have enough parts between my right tip and his to make a new tip.

My right tip panel was broken at the spar about 9 inches from the tip...not totally unreparable but a lot of work that quite frankly I would probably screw up. The next best option was to take my good parts and mate them with some less damaged components. The repair log below is the outcome of this effort.

David Beardsley was talking me through the focus points of this repair so the credit goes to him. He had considered making a jig to hold the wing in place while I mark a line to sand the parts to final fit. I thought I would screw that up too so I decided to make a mold from dap with my only remaining good right tip. My thought was that it would efficiently give me a great root reference and a perfect imprint of the tip section to fit the parts together.

Check out the pics - the final sanding is completed and the parts are fitting together quite well. IN the mold you cant even tell there is a seam! However the next phase will be interesting - the spars dont line up very well (+1-1 mm) so ill have to tie them in with gorilla glue for the expansion factor because I intend to use some rectangular carbon rod to tie in the spars.
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Old Mar 05, 2013, 06:01 PM
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What kind of material is "dap"?
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Old Mar 05, 2013, 07:06 PM
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Originally Posted by Francesco View Post
What kind of material is "dap"?
Drywall plaster ! Not very sexy material - it bubbles terribly under the wing but for the purpose of attaining a reproducible root and tip orientation it worked really well.

I tried using automotive bondo but the heat was too much when it kicked off and on a pike wing i tried it on it actually caused delams.

The only down side is that tray of plaster weighs about 70 lbs.

here are some more pictures - I worked the sanding down to a perfect fit - leading edge - trailing edge and wipers match perfectly - the stripes were obviously not done the same on the wings so there is a slight mismatch on the top red stripe the bottom looks like a black wingtip - because of the black white contrast you cant see the seam at all.

In the one shot you will notice the carbon rod I used to tie in the main and rear spars is offset for the main spar because of deviation between spar locations between wings - I used Gorilla glue which expands to take up any gpas and will tie in the carbon to the spar nciely ( I hope) for the rest of the joints I used West Systems 105/206 ( 6 hour cure) and micro balloons.
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Old Mar 05, 2013, 07:07 PM
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Joined Jul 2007
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Quote:
Originally Posted by Francesco View Post
What kind of material is "dap"?
Drywall plaster ! Not very sexy material - it bubbles terribly under the wing but for the purpose of attaining a reproducible root and tip orientation it worked really well.

I tried using automotive bondo but the heat was too much when it kicked off and on a pike wing i tried it on it actually caused delams.

The only down side is that tray of plaster weighs about 70 lbs.

here are some more pictures - I worked the sanding down to a perfect fit - leading edge - trailing edge and wipers match perfectly - the stripes were obviously not done the same on the wings so there is a slight mismatch on the top red stripe the bottom looks like a black wingtip - because of the black white contrast you cant see the seam at all.

In the one shot you will notice the carbon rod I used to tie in the main and rear spars is offset for the main spar because of deviation between spar locations between wings - I used Gorilla glue which expands to take up any gpas and will tie in the carbon to the spar nciely ( I hope) for the rest of the joints I used West Systems 105/206 ( 6 hour cure) and micro balloons.

Now all I need is about 13 inches of good right tip agains and I can repair the wing panel left over
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Old Mar 06, 2013, 07:30 PM
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AUW after repair came out at 59.11 oz
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