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Old May 17, 2010, 11:46 PM
JWs are Shear Fun!
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Quote:
Originally Posted by target View Post
I think the only bonus of bagging non-painted mylars is if you want to see how well you are doing with the layup....
But it seems like no paint makes pinholes much more likely.

If you wanted the best of both worlds, I suppose that you could use a coat of clear on the mylars, then layup.

I plan on doing that on the next wing I layup that has an all carbon wing, but I will spray broad stripes over the clear to make a naked carbon/striped wing bottom.

R,
Target
I like the idea of clear on mylar, but what clear would work? I had bought some satin acrylic artist's spray thinking the satin sheen would give the epoxy some grip. But it may just dissolve when the epoxy is put on it...
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Old May 17, 2010, 11:50 PM
JWs are Shear Fun!
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Primered Mylars

I went ahead and sprayed automotive primer on the mylars today. It started to rain as I was doing it. Isn't it May? Weird weather this year.
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Old May 18, 2010, 08:12 PM
JWs are Shear Fun!
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Well, the cold weather caused the mylars to curl up bad and the primer had to be removed. I am decurling them now. I will have to reprimer once the weather clears.
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Old May 18, 2010, 11:35 PM
JWs are Shear Fun!
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A long time coming

Wow, it has been a long time since I started this project. Today is the day I have been waiting for for quite some time now.

I aborted on primering the mylars again as they simply were not going to flatten out enough and the risk was too great of the primer debonding again. I went ahead and waxed them up and started laying glass. The glass layup for this plug is 1 layer of 7oz glass @ 0-90 and 1 layer of 7oz glass @ 45-45. I used West Systems with 209 hardener (extra slow).

The wing is in the bag. Everything looked good after I triple checked it. I quick pull of vacuum to straighten things out and in the beds she went. I put a bunch of weights on it and it is now sitting on my bench curing.

The wing tips will need some TLC afterwards, but nothing a little bondo won't fix. I tried to wrap the tip section with 7oz but the tip shape come out better next time with 4oz surfboard cloth.

I also spoke with my wood turner today. He is amped to turn some fuselage plugs for me. I will be finalizing the fuse design shortly and will post it here.

One more thing I still need to do is select tail surface sections and cut the tail cores.
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Old May 19, 2010, 06:58 AM
Detail Freak
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On the clear paint, my plan is to just use clear Krylon.....

On the curled mylars, what I do is very lightly tack them down to carboard for painting and layup. Not sure if that would help you or not, the primer might pull from the mylars after the layup is on them, after they were removed from the cardboard.

G/L, Target
PS I have some 209, but have never used it. I hope you plan to heat that wing a bit to cure the WS. I usually use 206....
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Old May 19, 2010, 10:49 AM
Stay in it!!!!
Riverside, California, United States
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Curled mylars are no good. In my experience, even if they are tacked down, they can still curl back up even with a few layers of carbon and resin weighing them down once you unstick them. As soon as I cut mylars to the shape I need I take them and roll them tightly the opposite way and they will hold themselves flat after that. If not I roll them tighter until they do. Roll them up tight the other way around. See what happens.
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Old May 19, 2010, 11:45 AM
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Heat helps to take the curl out as well. I would try throwing the reverse-rolled mylars under an electric blanket or in a hot box for a spell.

R,
Target
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Old May 21, 2010, 12:44 AM
JWs are Shear Fun!
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Thanks for the tips for the mylars. I have reversed rolled my spool for starters.
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Old May 21, 2010, 12:56 AM
JWs are Shear Fun!
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Wing is out of the bag. I have added filler to the wing tips and leading edge and shaped them close to final. I have started filling holes and got an initial primer coat on. It will take another coat or two of primer and at least one more round of pore filling to tidy things up. She looks perfect and true and very fast. I will have pics tomorrow.
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Old May 21, 2010, 10:04 PM
JWs are Shear Fun!
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Wing Plug

I am making progress on the wing plug. The top is almost complete and needs one more shot of primer and some wet sanding. The bottom needs another round of pore filling plus at least 2 more primer coats. The wing tips are almost perfect and just need a little more sanding before a final primer coat. I took some photos to show the progress:
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Old May 21, 2010, 10:33 PM
JWs are Shear Fun!
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Airfoil choice

...
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Last edited by Aerogance; Jun 01, 2010 at 10:58 PM.
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Old Jun 01, 2010, 11:00 PM
JWs are Shear Fun!
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Quick update: wing is completely filled and sanded. 1 or 2 light primer coats and it is ready to be polished. Still working on final fuse shape so I can have it turned. Will post pictures soon.
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Old Jun 02, 2010, 01:33 AM
JWs are Shear Fun!
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Closing in on the planform for the DC60

I am going to use a parabolic section for the fuselage. It isn't easy to get the shape I am looking for but after a few nights of working with conic sections I am getting close. I need to get the wide point of the fuse at or behind the wing trailing edge. I am ultimately aiming for a 1.5 degree minimum wing fillet a.o.a. for (theoretically) smaller vortices at the wing fillet when yawing through the shear.
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Old Jun 02, 2010, 11:30 PM
JWs are Shear Fun!
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Picked up more primer today. Also got a tube of 7715 and I must say that is the best product I have ever used. Should have the wing plug completed this weekend when I have time to work on it.
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Old Jun 04, 2010, 08:32 PM
JWs are Shear Fun!
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Wing plug 99% complete

The 7715 putty made all the difference. I have just a handful of spots to touch up before polishing the plug and waxing her up. She is looking really good. Here are the latest photos:
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