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Wing Twist

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Davcoberly(at)wmconnect.c
Guest

Posted: Thu Apr 03, 2008 11:03 am Post subject: Wing Twist

As hard as I tried not to I have one wing that is twisted some is there any tolerance for wing twist as there is with the stab and elevator. I tried drilling out both rear skins and when clecoed back the twist is back. I must have drilled it while it was twisted but at the time I sure didn't think it was. Right now I'm ready to take a sledge hammer to the whole thing.  David     [quote][b]

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John75142

Joined: 05 Dec 2007
Posts: 56
Location: Kaufman, TX

Posted: Thu Apr 03, 2008 11:48 am Post subject: Wing Twist

I feel your pain brother. If possible try and figure out which skin is  giving the problem and just make the one over. I know that is not the answer you  might of been looking for but I think I would start there.

  

 John (Scratch building 701)

Kaufman, Tx

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_________________
John Short

Trainnut01(at)aol.com
Guest

Posted: Thu Apr 03, 2008 12:32 pm Post subject: Wing Twist

David

 The trailing edge of my left wing is twisted up 8mm at the outboard end.  The right trailing edge is twisted up 12mm at the outboard end. Chris told  me to leave them alone.

 If they were twisted in opposite directions his answer might have been  different.

 Carroll

  

 do not archive



Planning your summer road trip? Check out AOL Travel Guides.

  [quote][b]

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larry(at)macsmachine.com
Guest

Posted: Thu Apr 03, 2008 1:03 pm Post subject: Wing Twist

Hi David,

In as much as you've got the holes for the trailing skins done, I'd 

recommend you match jig the twist you want with one rib end of the wing 

skin clecoed and mark the skin

for the actual hole positions seen partially thru the skin. Then 

translate key new positions to the next skin and cleco it secure.  Check 

the twist again and you should be good

to go. Better to make this next skin yourself,



Larry McFarland 601HDS at www.macsmachine.com



Davcoberly(at)wmconnect.com wrote:

 	  Quote: 	
		   As hard as I tried not to I have one wing that is twisted some is 

 there any tolerance for wing twist as there is with the stab and 

 elevator. I tried drilling out both rear skins and when clecoed back 

 the twist is back. I must have drilled it while it was twisted but at 

 the time I sure didn't think it was. Right now I'm ready to take a 

 sledge hammer to the whole thing.  David

 *



 *

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Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Thu Apr 03, 2008 1:10 pm Post subject: Wing Twist

David



 I am working on my right wing right now, and I confess to being a bit confused regarding how to determine twist. How did you determine that your wing was twisted?  



 I can tell you what I've done, and where I'm at, but it would be faster to just point you to my builder's log--check the entries for 3/5 and later, especially the ones for 3/25 and later. See the link below. There are lots of photos. The bottom line is that, as near as I can read a spirit level, my wing satisfies the specs for avoiding twist given in PAM 6W8A, i.e., both spars are level and the spar angle is 9°. But when I put the bottom skin in place, it was too wide  by >=2-mm inboard  and by >=10-mm outboard. Caleb told me that such problems are usually an indication of twist in the wing. So, I remeasured: my supporting beams were level, the spars were level, and the spar angle measured 9°. Hmm. Caleb suggested that I let the skin overlap the rear spar as far as possible while meeting edge & flange distance specs. I could do that and just barely meet specs. But since it didn't allow any room for error (not wise for me), I decided, instead, to let the skin overlap the main spar and drill a new rivet line  there.



 I did not make up the support blocks as described in PAM 8AA. Since I have 12 ft long 2x2 steel beams that I can level on my table, I thought they would give me a better reference. I clamped the shimmed-up beams to the table so that they cannot move.



 It's at times like these that I would wish for a builder assist person who could look at what I've done and tell me whether it was good enough.



 After writing all this just now, I realized that I had never measured the skins, so ... the inboard end of the skin measures 917-mm vs. 910-mm on 6-W-8 and the outboard end measures 720-mm vs. 705-mm on the dwg. Duh. I can't believe that I didn't measure them when the problem 1st surfaced. I guess I'd best call  ZAC, again. 



 Also, there was another problem with the bottom skins--the slots for the tie down rings were cut on the outboard side of rib 9 instead of inboard. Has anyone else encountered that? Also, my right nose skin has prepunched pilot holes for the 30 gal tanks rather than for the 24 gal tanks I have.



 Terry



 

 At 02:59 PM 4/3/2008 -0400, you wrote:

  	  Quote: 	
		  As hard as I tried not to I have one wing that is twisted some is there any tolerance for wing twist as there is with the stab and elevator. I tried drilling out both rear skins and when clecoed back the twist is back. I must have drilled it while it was twisted but at the time I sure didn't think it was. Right now I'm ready to take a sledge hammer to the whole thing.  David 	
 

 

 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/     [quote][b]

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_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

naumuk(at)alltel.net
Guest

Posted: Thu Apr 03, 2008 3:16 pm Post subject: Wing Twist

Dave-

     In spite of the fact  that I had problems with the spar web pre-drilled holes, this was the  answer for me. Avoid movement and you avoid trouble. 

     If you have to trash the  existing skins, you can make new ones relatively cheaply in a short time with an  Olfa knife.

     You can tell this is an old  picture- the windows are open!!

                                                                    Bill

                                       do not  archive

 [quote]   ---

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Davcoberly(at)wmconnect.c
Guest

Posted: Thu Apr 03, 2008 4:23 pm Post subject: Wing Twist

Terry, 

That is how it checked mine main spar at 9 deg and level then rear spar ended up not level. From forward outboard to rear inboard about 10mm off.   

Thanks to all for the help!  David     [quote][b]

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graeme(at)coletoolcentre.
Guest

Posted: Thu Apr 03, 2008 6:36 pm Post subject: Wing Twist

The biggest problem is if you build two wings on a bent bench and they both  have the same twist.

 your twist should be ok

 The problem is magnified if you built two wings with the same  twist.

 you end up with LE of one wing up and TE of other wing up.

 When you set up your struts you can fix a minor twist.

 the two inboard mounts are set up and you the set up front strut and if  needed twist wing and setup rear strut to repair twist.

  

 Graemecns  

 [quote]   ---

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n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Fri Apr 04, 2008 7:54 am Post subject: Re: Wing Twist

Drill out the rivets on the top or bottom (low wing do the bottom, 

high wing 801/701 the top) pop the skins. twist it straight and 

jig it in place (a laser level is a great help for this). redrill with #20

and re-rivet with A5's. That's the best way.



Once painted the A5's are hardly noticeable.



I completely unriveted the top skin on my 801 wing in two hours

to fix a mistake I made. Just drill the tops off the rivets, then pop the skin

by sliding a plastic putty knife between the skin and the ribs to pop it

off the rivet stubs, then pull the rivet stems from the backside with pliers.

I didn't damage a single hole on the entire wing with this method, and

I did it on two wings so I consider myself an authority on un-rivetting 



It's a single weekend job to fix your mistake, so not a big deal. 



Jeff

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