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Well crap.

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Dwayne Donnelly:
I swear this wing came off the board dead straight, covering is off and I need ideas on how to straighten this, it's 3 degrees up in the middle, tip and root are zero.  HB~> HB~> HB~> HB~>

Gerald Arana:
Try a mono coat iron to heat it up. If that doesn't work well enough, us steam or hot water on it.

Good luck, Jerry

Ken Culbertson:

--- Quote from: Dwayne Donnelly on October 06, 2020, 08:17:07 AM ---I swear this wing came off the board dead straight, covering is off and I need ideas on how to straighten this, it's 3 degrees up in the middle, tip and root are zero.  HB~> HB~> HB~> HB~>

--- End quote ---
Looks like a case of **warped spar***.   Can you put a straight edge on the spar top and bottom and have no gaps.  In other words is the spar warped. TE's don't normally warp on their own without covering, but they will if the spar warps and the ribs push it down.  What is the construction?  If it is D-Tube and the front appears straight you are going to have to cut the ribs on one side to relieve the tension.  Probably have to remove the T/E sheeting on one side.  Do you cut your T/E planking from the same sheet so that it will have similar warp tendencies?  Do you add spacers or cross braces to keep the T/E from warping?  If not, now is the time.  Let's hope it is not a deformed D-Tube.  Is the LE straight?  It is possible that it is bowed as well.  Opposite if it is the spar, same if it is the LE planking.

If it is not D-Tube you have the joy of knowing that anything you do the TE will put pressure on the LE.

In either case you are going to have to relieve the pressure and replace anything that you have to bend to get into place.  Jigs can be your downfall if you allow them to force warped wood into place.
I hope others have a better solution for you, but I have never been successful in removing a warped TE without surgery.

You can use heat but that is a whole-lotta-warp and unless you find the cause it will come back.

Ken

PS - you said that the covering was removed.  Was it warped when you covered it?  Was moisture or heat involved?

Ken Culbertson:

--- Quote from: Motorman on October 06, 2020, 10:43:54 AM ---Spray the frame with water and stake it out so it's straight. If you go too far or not far enough just do it again.


Motorman 8)

--- End quote ---
This may work but consider that it warped initially because either moisture or heat caused the wood to relax tension unheavenly.  I am guessing it was heat since the wing appears to have been monokoted.
If that is the case a good portion of the warp should lessen once the covering is removed and it sets for a while.  Balsa will mold quite easily and you can probably soak it and dry it out on a jig and get the warp out for now but if the cause is bad alignment (internal tension) or wood mismatch on the planking it is just going to come back (or maybe even worsen it down the road) and pulling it into place with the covering won't last the summer.

One thought on Monokote.  Different colors shrink differently.  I have monokoted a lot of planes and I have never had one that used different base colors on the top and bottom that didn't need a lot more maintenance that ones that used the same.   Mostly white and dark colors like red/blue.

Bottom line, the warp has to go.  Your flap hinges will never forgive you.

Ken

This just popped into my head.  I used to fly a lot of Nordic.  Both A-1 and A-2.  Warps are disaster in that event.  My flying buddy (who was a world team member) always cautioned me to dope the entire structure and let it set on the jig for several days before applying the Jap tissue.  I also did that to my stunt ships simply because (not just the planking, I did everything inside and out). Three A-2's and two stunters sat in my attic for over 10 years and none of them warped.   May have nothing to do with it.

Dennis Toth:
Dwayne,
Is just the trailing edge wrapped or the whole wing? If the whole wing it may not be a big problem just a little dihedral. If the trailing edge I would jig it so that it is 1/4 over sprung then use a heat gun to heat the wood area. You may need to apply the heat several times while it is in the jig to get it to take. When you heat it keep the gun moving but you will need to let it heat soak to get the heat into the inner part of the wood. I would heat top and bottom a total of about 20 minutes each side flipping which side you applied heat to. Let it sit in the jig at least a day then check. May need to repeat.

Best,    DennisT

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