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Building Tips and technical articles. => Building techniques => Topic started by: Avaiojet on July 13, 2012, 05:16:13 PM
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These two modelers go into this Bar.
Just kidding.
I haven't fixed a twisted wing with open bays in 50 years. Pan, water, heat, a bit of steam and you're good to go. Right? Well hold on a minute.
My Flite Streak, an original kit BTW, had two warped parts. Nothing major, just the LE and TE.
No big deal, small arch, probably off a half inch. Hardly no-ticable if your tall.
Anyway, lazy as I am, I opted to not fix the part but to just assemble the wing an build it like it is. So, I had one bow facing up and the other facing down.
The wing was straight as an arrow except for this, if that makes since.
Six months later, I developed a bit of enthusiasm because of another Flite Streak build thread. I'm on it again building and liking it. Still cannot get those bowed LE and TE'ers out of my mind.
Now, back to that boiling pan of steam.
Only steam I could come up with was from the cook top.
Cabinets above in the kitchen so that won't work.
So now I find myself outside standing in front of the grill and wondering what kind of pan I can put in there to boil water for this steam job.
Boy it was hot yesterday in sunny Florida and that swimming pool sure looks really inviting.
So I said, "Why not!"
I went and got the wing and submerged the whole thing in the swimming pool. Yup, soaking wet it did get.
I jigged it up and let it dry overnight and "presto remco" what an improvement. Not 100% but still a considerable improvement.
So, I guess you never know where a hot day and a swimming pool will take you.
Charles
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For those familiar with Steve Wolfe's beautiful full scale Gee Bee R-2 replica flown by Delmar Benjamin (now in the Smithsonian), Steve soaked the plywood wing skins in a swimming pool for days before sheeting the wings. I think your on to something Charles!
Paul
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Charles, it probably would have been better to have left that wing in the jig for at least a few if not several days to be sure all the moisture was gone. Don't be surprised if it warps again.
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Color me quite skeptical. Especially as the wing is still bent, just not as much.
For others looking in, it being assumed Aviojive will proceed as if his is a good idea, it would probably be best if such a wing were simply scrapped, what with there being some more work involved in creating a finished model.
On a more basic level it is quite optimistic to assume bent wood will result in a straight wing. To further assume a bent TE piece will effectively offset a bent LE piece, especially on something like a Flite Streak wing, is exceedingly optimistic. (Yes, my understate-the-problem button has been engaged.)
Good luck Aviojive on this wing. But my very best advice is to scrap it. Barring that I would put forth the idea that it needs to be jigged up again for a couple weeks and then checked. Even at that it would not surprise to see the wing in finished model go all pretzel on ya down the road.
Dan
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I have found few kits that had the preshaped leading/trailing edges to be straight. I would line them up to see if the bow was the same direction for both peices. Some planes had dehidral and some had anhedral. Never noticed the flying of the planes to be different than the ones that did have a straight LE/TE, which were few, very few. Even covering with silk/nylon I would wind up with bows in the wings. H^^
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"Painting" the areas of warp in both the LE piece and the TE piece with a LOT of ammonia (really slopping it on to get the wood as saturated as possible) will affect a changing of the wood's cellular structure which in turn can possibly lead to the pieces being jigged to dry with the pieces straight. Probably adjust the jigs to go a bit past straight during the drying. Let the parts dry for a couple days so that the ammonia is completely evaporated and a set is obtained in the wood.
BIG Bear
RNMM/AMM
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charles,,i suppose it depends upon what you want,, if you want a reliable flying airframe,, I doubt this wing will get you there,, but then if you just want something to talk about,, and maybe some day go out and go around in circles,, then it wont matter much,,
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I also use the ammonia trick. I pin the warped part to my building board with wax paper between the part and the board. I have a spray bottle that I keep the ammonia in and then I soak the piece with ammonia. I let it set for a couple of days to make sure it's dry and then un pin it from the board. I then have a straight piece.
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for what its worth,, ammonia can cause structural issues within balsa,, as in making it brittle and failure prone.
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for what its worth,, ammonia can cause structural issues within balsa,, as in making it brittle and failure prone.
Mark,
Yes, you're correct. I remember that being mentioned in an article I read about tears ago about bending sheeting.
It was mentioned that ammonia wasn't necessary and it could make wood brittle.
I bent this sheeting without using ammonia or a swimming pool. That would be without bleach.
Thanks for the reply!
Charles
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That's just plane awesome. I would have gone through dozens of pieces of wood before I kept one from splitting. I have yet to build a built up fuse so all of you guys amaze me.
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That's just plane awesome. I would have gone through dozens of pieces of wood before I kept one from splitting. I have yet to build a built up fuse so all of you guys amaze me.
Nathan,
That's an R/C model going CL.
No reason to be amazed though, all you have to do is do it. Hit a stumbling block? Just ask the Forum, I'm sure you'll get plenty of answers.
An easy first full fuselage kit would be something like, The New American. ;D n~ LL~
Private joke.
I may have enough parts to provide a fuselage. You would need a Sig Banshee wing, available as a wing kit from Sig.
If you consider taking on the project, PM me I'll get you what you need and get you through the build. ;D
Yeah Baby!
Charles
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When I built my first Nobler kit many years ago, the bottom sheet was to be molded. Did not know about amonia then. Just put the sheet in a tub of water with some weights(canned vegatables) to soak over night. The mold was an old baseball bat. Wrapped the sheet of balsa around it and let it dry for several days. No cracks and formed to the fuse with very little effort. H^^
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That's just plane awesome. I would have gone through dozens of pieces of wood before I kept one from splitting. I have yet to build a built up fuse so all of you guys amaze me.
the other way to do this (that is easy, and FAST) is to attach the bottom of the sheet to the fuse side - spray the outside with water from a spray bottle. Use an iron and push it around the formers. the steam bends wood, and the heat from the iron dries out the water.
other bonus is you van glue it straight away - and if you take the iron off -the sheet holds is shape....
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Wynn, does that method lead to stress cracks over time?
LOL Charles I think I'll stick with a couple more profiles for now. I do have an engine in the box waiting for a Nobler.
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the other way to do this (that is easy, and FAST) is to attach the bottom of the sheet to the fuse side - spray the outside with water from a spray bottle. Use an iron and push it around the formers. the steam bends wood, and the heat from the iron dries out the water.other bonus is you van glue it straight away - and if you take the iron off -the sheet holds is shape....
Wynn,
All these years I've been in this hobby and that's the first time I've heard of that method.
It's absolutely a great idea. Thanks for that!
Charles
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Ammonia is not needed on balsa. Ammonia will soften the lignin and subrin in wood; however, balsa has little or none of these compounds. The problem is to get it saturated with water. Adding a little Simple Green to the water will make it soak a lot better.
If I were dealing with a warped leading edge and trailing edge as mentioned here, I would split them lengthwise and reglue them in a jig. That works pretty well.
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Guys,
The easiest way to get out a warp is with a heat gun. Heat the part equally on both sides, bend it to a little past where you want it, hold till it cools and check. Redo as needed, in short order you will get a feel for how much over you need to bend/twist the part. Back in the day we use to steam the wing with a tea kettle. I use to think the "steam" was what was getting the warps out. Wrong - it was the "heat" of the steam that did it, that's why a heat gun works and its way faster. This will work with covered/painted wings also, just need to watch how much heat you put at any one spot.
Best, DennisT