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Thread: New member building a PA18-95

  1. #241

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    Vic,

    No I didn't ask him for drawings. I don't know about the "figured it out from photos" either. This was just my rendering of something close to what Javron does on their wings that looks like it makes sense. There is no engineering behind what I have done, but I don't think it will weaken the wing.

    I deemed it necessary because I have seen some pictures taken from a certain Javron Cub on amphibious floats. Alaska, Russia(nearly), the Bering Sea and the like. I don't want to be left out of that kind of action if I live long enough to finish my plane. Sounded like Javron did some testing and determined those wings needed a beef up at that kind of gross. Those wings have the same spars I do and I do like to fish.

    From reading what others have posted here and from what my gut tells me, if my wing was going to crinkle, it would likely do it just outboard of the strut attachment points. A full wrap outboard of the front strut attachment point on the front spar and a boxing in of the false spar to the rear spar in the 3 bays surrounding the rear strut attachment point looks like a good idea for the weight needed to do it. I also like the fact that I didn't have to drill holes in my rear spar in places that one doesn't normally do to attach ribs.

    It is spooky how floppy aluminum wings are until you get the leading edge on and amazing how dramatically different they are once on. I don't have any experience building wood wings, but I would imagine yours will be quite a bit stiffer. I'm not qualified to offer any suggestions there.

    I post lots of pictures in hopes someone will speak up if they see something stupid that I have done. This is my first rodeo, I'm learning as I go.

    Sorry I'm not more help.

    Jim
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  2. #242

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    6oz, 6 Day Mistakes

    Made some more errors. 1st one I didn't realize until I had Port wing buttoned up and was ready to drill three holes in Starboard. Laid my aileron bracket up from the wrong hole. About 1-1/4" too far inboard. Looked like it would put the cable in one hell of a bind, had to change it. Made up a different spar stiffener so I could fill the two mistake holes and have it look somewhat planned. Luckily I had already made both top spar beef up pieces...they made nice patterns for all of the holes except for the aileron bracket (had to remake both, had to wait for replacement materials).

    Second mistake was laying out the false spar on the Starboard wing. Measured it out, got all the holes where they should go, but somehow got it about a 1/4" too far inboard when drilling holes in ribs. Edge distance for rivets holding one side of my aileron/flap brackets was too close, looked like and was garbage. Had to make reinforcement plate thingys for the outside of the false spar to make myself happy. Made both wings match.

    Had to take a SWAG on the lower aileron pulley bracket's angle that mounts on the front spar. Looked like if mounted perfectly horizontal with the pulley cage not pictured, it would again put the cable a bind going to the next bracket inboard that mounts on the compression member.

    Making forward progress again. Boys have been helping buck the rivets I can't squeeze. Left handed one decided the dog needed to be wearing safety glasses...

    Thanks,

    Jim
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  3. #243
    skywagon8a's Avatar
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    Quote Originally Posted by Jim A. View Post
    Just a heads up. In order for the control cable which runs from this pulley to the top aileron horn to be properly aligned, the horn needs to be twisted towards the pulley 3 degrees. This is on Piper's aileron horn drawing.
    N1PA
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  4. #244

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    Quote Originally Posted by skywagon8a View Post
    Just a heads up. In order for the control cable which runs from this pulley to the top aileron horn to be properly aligned, the horn needs to be twisted towards the pulley 3 degrees. This is on Piper's aileron horn drawing.
    and also remember this when you do your fabric covering that the teardrop cover for this is mounted at a angle also, not straight front to back.
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  5. #245
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    Quote Originally Posted by Bearhawk Builder View Post
    SEM products self etching primer is the best I've found in a rattle can. Most epoxy primers don't need a topcoat, Polyfiber's epoxy is tough as nails, PPG's DP epoxy is another good one.

    Will Poly Tak lift the Sem Primer or Paint ?

  6. #246
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    Regarding the wings, focus on the budget, I do not see the difference as critical. Regarding his opinion, he would choose aluminum.

  7. #247

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    Wings are flying, kind of...

    Finally got starboard side leading edge done. Oldest son helped buck rivets. Good to spend time with him in the shop, but also kind of sad. He's a senior, he leaves for basic training in June. His little brothers are going to have to help in his absence. Plan was to have this project done by now, but things rarely go as planned. Maybe when the oldest is done with school, I'll have it done and he can show his old man how to fly it.

    Flush riveted the leading edge. Wanted to try it, like it, but it was a lot of farting around. I was toying with trying to flush rivet the flaps and ailerons, but after doing the leading edge, I'm definitely not going to for many reasons.

    Rigged up a pulley system to get the wings out of the way when necessary and have them at hand at home for trial fits to fuselage when that time comes. Very cool to stand underneath them for the first time.

    Building tanks next, then flaps and ailerons. Going to try my hand at making my own carbon fiber tank lids and wing tips after that.

    Thanks,

    Jim
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  8. #248

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    Torch welded aluminum (donít laugh)

    Hadnít played with this in a while, really need to be in the right frame of mind to do it, and watch it like a hawk. Look away for a second, garbage. One beer minimum and one only. This is .050 6061 T6 with 1/16Ē 4043 filler, size 0 Victor tip turned way down. Not perfect, but gaining on it. My tanks will be .050 5052 H32, same filler. Going to torch weld corners, one seam, cross tube, filler neck, and over rivets that fasten baffles. Will tig bungs. Was going to have Javron send me blanks, but his are .040, and this will be hard enough for me with .050. He is supplying the bungs, filler necks and cross tubes. Very helpful and friendly guy.
    Why torch weld? Because itís old school, challenging, and I want to say I did it. Not cheaper, may not be better or as pretty as tig, but I guarantee you will waste a lot of time, money and material getting somewhat proficient at it.

    Thanks,

    Jim
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  9. #249

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    Tig and torch welded aluminum comparison.

    WARNING, IMAGES MAY BE DISTURBING TO REAL WELDERS.

    Got my .050 5052 on Thursday. Did some more torch welding. Used a Smith Little Torch tonight with their size 5 tip which is slightly smaller than a Victor 0. Then did some tig, weighed, compared, destroyed. Both weigh the same, youíd think that gobby looking torch weld on the right would weigh more, but it didnít. One of the reasons Iíve been farting around with torch welding aluminum was that I had read some claims to less prone to weld failure, better penetration and the like. When I cut what I had done tonight apart perpendicular to the weld and bent it backwards, it at first looked like I did have more weld that followed the flux on the back side. After a little prying with a beater screwdriver, I realized that was not the case, the aluminum was just annealed further back from the weld.

    Conclusions: I think I could make either weld hold gas. Tig is considerably easier and prettier. I donít have to clean up the corrosive flux with tig. Both welds will eventually break, it was slightly easier to break the tig weld. Going to try some flux formulated to work better with 5052 before I totally decide, but after tonight, Iím not really seeing the advantages I thought I might with torch
    welding this particular alloy in this application.

    Thanks,

    Jim
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  10. #250
    skywagon8a's Avatar
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    Quote Originally Posted by Jim A. View Post
    One of the reasons I’ve been farting around with torch welding aluminum was that I had read some claims to less prone to weld failure, better penetration and the like. When I cut what I had done tonight apart perpendicular to the weld and bent it backwards, it at first looked like I did have more weld that followed the flux on the back side. After a little prying with a beater screwdriver, I realized that was not the case, the aluminum was just annealed further back from the weld.
    Interesting and good practice. Do you suppose that by being annealed further back from the weld there is more flexibility in the sheet near the weld? A shock absorber of sorts? When the sheet is not annealed some distance away from the weld but is stiff right up to the weld it would be more prone to cracking.

    What 5052 are you using? 5052-0 or 5052-H32? Would one be more prone to crack than the other?
    N1PA
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  11. #251

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    Pete,

    Good point. Iím using H32. I would guess O would be less prone to cracking, but it would only be a guess. I would also guess that O would harden anywhere that it was heated, so it might be the same thing only in reverse. Just changing where hardened aluminum meets soft. Welding aluminum with a torch is different. My experience has been that you never really get a bright shining puddle like you do with tig. Doesnít really drastically change colors when itís ready to add filler. Once you see the skin wrinkle, itís time. Add filler, move and get the heat away or you will quickly make a hole. The end result is a rougher looking weld that looks more like a brazed joint. You can sink the weld into the joint and smooth it somewhat by going back over the weld with the torch, but it is still ugly. Iím going to try the different flux formulated for 5052, if I donít get different results, Iím just going to tig the tanks. Once the tanks are done, Iím going to try torch welding some 3003. Iíve heard it plays nicer with a torch and Iím curious. Not before these tanks are in the wings though!

    Thanks,

    Jim
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  12. #252
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    You are to be congratulated for your gumption to do this yourself. I've welded aluminum both tig and gas, it's not easy. It takes practice and proficiency to do an acceptable job. Good for you, go for it. You will have something to be proud of.
    N1PA
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  13. #253

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    Thanks Pete. Most people would call what I have something other than gumption. Thank you again for your kind words. I truly admire good welders, sheet metal guys and manual machinists. I may never be one, but it is truly satisfying to make the attempt.

    Thanks,

    Jim
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  14. #254
    www.SkupTech.com mike mcs repair's Avatar
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    Donít mater the h number. Once you hit it with torch you remove the heat treatment, unless you dunk it in water at the proper time. The h is just about how they heated and then cooled it....


    Sent from my iPhone using SuperCub.Org

  15. #255
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    For welding the H number isn't important but, the -32 does reduce the denting possibilities and increases the overall stiffness of the completed part.
    N1PA

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