Desert Center Wing Repair - 2/3/2007

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Saturday I headed down to work and did the final layup - the inside top closeout of the lower winglet rear area - 2 BID. I then mixed up a bunch of micro and finished the lower winglet, patch area, and any voids and pinholes, as well as the very few low points in the previous microing. An oven was available, so I put the wing in at 120 F while I went to get some lunch and watch a co-worker fly a hydrogen powered rocket (from Estes) with his 2.5 yr. old daughter - see:

Estes Hydrogen Rocket

cool when it works, but doesn't always launch.

After 2 hours in the oven, the West fast was hard, so we removed the wing and I spent a few hours finishing the contouring with 40 grit, then going over everything lightly with 80 grit.

I then used polyester auto body glazing compound over everything to fill what voids and pinholes were left. Before anyone tells me that I shouldn't use polyester stuff, I know that, but I checked with a bunch of the bodywork guys at Scaled and they said they had NEVER had a problem with delams or non-sticking or shrinking. Maybe it's just the stuff we have at work - high end bodywork stuff, and NOT plain bondo, but they said that if I kept it VERY thin, it'll be fine. Anyway, I put it on and then 20 minutes later sanded almost all of it off - got 95% of the pinholes/voids on the first try, and almost all the rest on the second.

I sanded the glazing compound with 100 grit and then finished up with 220, using a dual action air sander for the non-contouring sanding - just to bring the glazing down to the contoured level. That worked very well and saved a LOT of time.

Lastly I mixed up 12 OZ of white primer (Polyprimer - another polyester based material that is commonly used below urethane paints at work - again, the folks that should be in the know said that they had NEVER had a problem with it under any paint). I used a small sprayer to put 3 coats of primer on all re-worked surfaces and let it dry overnight.

Here's the wing top surface after 100 and 220 grit dual action sanding

Here's the aileron after 100 and 220 grit dual action sanding

Here's the winglet outer surface after 100 and 220 grit dual action sanding

 


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Copyright 2007, All Rights Reserved, Marc J. Zeitlin
e-mail: marc_zeitlin@alum.mit.edu

Last updated: June 28, 2010