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Building Tips and technical articles. => Building techniques => Topic started by: Chris Fretz on April 01, 2016, 11:29:17 AM

Title: Joining wing halves
Post by: Chris Fretz on April 01, 2016, 11:29:17 AM
Can two built up balsawood wing halves be joined with only one inch wide fibreglass cloth.
Title: Re: Joining wing halves
Post by: Paul Wood on April 01, 2016, 12:04:11 PM
I wouldn't trust it. I would suggest cutting the strip into lengths about 2+ inches long. Then epoxy the strips edge to edge making the reinforcement area much larger.

Paul
Title: Re: Joining wing halves
Post by: Tim Wescott on April 01, 2016, 12:10:25 PM
Picture, please.  If there's spars those should be joined with their own reinforcement.  One thing that Stunt has taught me is that it takes a lot less center-section reinforcement to make a sturdy wing than you'd think -- I'm pretty sure that's because RC wings are fortified against bad landings, and CL landings tend to either be mild or disastrous, without much in between.
Title: Re: Joining wing halves
Post by: Mark Scarborough on April 01, 2016, 02:51:49 PM
I have typically built my wings in halves, complete with shear webs, cap strips and sheeting, EXCEPT I dont apply the center section sheeting ( the portion that fills in between the leading and trailing edge sheeting and is usually about a foot long)
Then I join the halves, and apply the center section sheeting which bridges the joint in the center section. That gives you a solid bridge across the center section.
Title: Re: Joining wing halves
Post by: Tim Wescott on April 01, 2016, 02:54:06 PM
I have typically built my wings in halves, complete with shear webs, cap strips and sheeting...

I should mention that for CLPA, with its flat wings, I build the whole wing at once, all on the same jig.  There's probably not a huge advantage over the way Mark does it -- it's just another way to achieve the same end.
Title: Re: Joining wing halves
Post by: George Grossardt on April 01, 2016, 04:32:18 PM
What about stunt wings with dihedral?  I have seen where they are built in halves but no discussion about joining them.  I suppose one can do it like FF wings except those aren't sheeted at the breaks most of the time.  Aircraft like Pat Johnston's Mustang or Spitfire come to mind.

Thoughts?
Title: Re: Joining wing halves
Post by: Brett Buck on April 01, 2016, 06:13:24 PM
Can two built up balsawood wing halves be joined with only one inch wide fibreglass cloth.

   Probably, depending on what else is holding it together and how good the fits are. I wouldn't - I would at least put doublers/joiners to connect the spars, LE, and TE wood in the center. It's OK to hold the sheeting, assuming the rest of the fit is *perfect*.

    I have made *many* foam wings where the only connection in the center section was the sheeting and the fiberglass, and butt-joints at the LE and TE, with a fiberglass/epoxy reinforcement strip, and there was no issue. The foam adds essentially nothing to the system, so it was the sheeting and the fiberglass doing the majority of the job. But it must fit *perfectly*.


    Brett
Title: Re: Joining wing halves
Post by: Mark Scarborough on April 01, 2016, 08:21:31 PM
What about stunt wings with dihedral?  I have seen where they are built in halves but no discussion about joining them.  I suppose one can do it like FF wings except those aren't sheeted at the breaks most of the time.  Aircraft like Pat Johnston's Mustang or Spitfire come to mind.

Thoughts?
I learned how to build my wings from Pat, I should mention I generally add a couple sub spars in the center section, 1/8 x 1/4 layed flat and inset into the ribs in the area where the center section sheeting is laid in. if you plan it right you can place them where the jionts fall in the center section sheeting. I have never had a wing fail, including some rather dramatic rapid stop manuevers with the ground,, other parts fail around them. but like Brett says, the fits must be precise
Title: Re: Joining wing halves
Post by: Chris Fretz on April 02, 2016, 06:06:56 PM
Picture, please.  If there's spars those should be joined with their own reinforcement.  One thing that Stunt has taught me is that it takes a lot less center-section reinforcement to make a sturdy wing than you'd think -- I'm pretty sure that's because RC wings are fortified against bad landings, and CL landings tend to either be mild or disastrous, without much in between.
A friend of mine wanted to know if I could ask this on here. I don't have a picture. But you guys cleared up what he wanted to know. Thanks!
Title: Re: Joining wing halves
Post by: Steve Helmick on May 05, 2016, 07:52:08 PM
Maybe we could get Mark to describe how he and Pat modified the Brodak P-40 ARF to put the dihedral in it? That would give the rest of us a clue about joining a 2-piece balsa wings. Might be able to do a search and find post a link...which I'll give a try.  VD~ Steve

Edit: There must be a sekrit to what to enter for "search". I entered "P-40 ARF Dihedral" and got this question in return:  "You may have meant to search for "p-40" Afr dehydrate."  I have officially given up! 
Title: Re: Joining wing halves
Post by: Chris Fretz on May 05, 2016, 09:13:39 PM
Maybe we could get Mark to describe how he and Pat modified the Brodak P-40 ARF to put the dihedral in it? That would give the rest of us a clue about joining a 2-piece balsa wings. Might be able to do a search and find post a link...which I'll give a try.  VD~ Steve

Edit: There must be a sekrit to what to enter for "search". I entered "P-40 ARF Dihedral" and got this question in return:  "You may have meant to search for "p-40" Afr dehydrate."  I have officially given up! 

How well does a plane fly upside down with a dihedral?
Title: Re: Joining wing halves
Post by: Mark Scarborough on May 05, 2016, 10:01:06 PM
really makes no difference, assuming its all done right,,
Title: Re: Joining wing halves
Post by: john e. holliday on May 06, 2016, 11:23:28 AM
I'm going to do a plug here.  The great Al Rabe posted over on Stuka Stunt his method of constructing wings.   Better yet go to the Vendors section and get his discs about his building of his planes.   I have his Mustunt II that I need to get too.   I also have his discs.   I try to build my wings in one piece using a jig.  The splicing of spars and straight leading edges is not done in the center section.   I do the splices in out board portion of the wing and solid sheeting in the center section. H^^
Title: Re: Joining wing halves
Post by: Steve Helmick on May 06, 2016, 02:34:25 PM
really makes no difference, assuming its all done right,,


The objective is very simply to put the LO's up where the vertical C of G is, as the designer (Pat Johnston) intended. The stock P-40 ARF (if the wing is straight) typically flies outboard tip down when upright, and up when inverted. Some will say that they "fix" this with a flap tweek...I would say that they are just creating another problem, or are not critical enough in their requirements. Always fix the real problem, even if it isn't the easy way.  D>K Steve
Title: Re: Joining wing halves
Post by: Mark Scarborough on May 06, 2016, 02:45:13 PM
Ok talking apples and oranges here, I was answering the question about inverted flight with dihedryl, and Steve, you are correct, the dihedryl only functions to align the leadouts with the verticaal center of gravity.  My comment was strictly refering to there being no negative impact of having dihedryl ( correct dihedryl that is) on inverted flight, excepting that without it you will have problems if the airframe was designed to incorporate it
Title: Re: Joining wing halves
Post by: Randy Powell on May 06, 2016, 08:28:10 PM
I build mine in one piece.
Title: Re: Joining wing halves
Post by: Howard Rush on May 07, 2016, 01:21:55 AM
Ok talking apples and oranges here, I was answering the question about inverted flight with dihedryl, and Steve, you are correct, the dihedryl only functions to align the leadouts with the verticaal center of gravity.  My comment was strictly refering to there being no negative impact of having dihedryl ( correct dihedryl that is) on inverted flight, excepting that without it you will have problems if the airframe was designed to incorporate it

See post #7 here: http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=287401&mesg_id=287401&listing_type=search#287477
Title: Re: Joining wing halves
Post by: Mark Scarborough on May 07, 2016, 09:41:27 AM
rHOward,
are you in line for any of those royalties, or do you have to wait for someone to do a four engine jet stunt ship...
I forgot about this post ,, I am actually surprised the guys in the black suits and SUVs havent picked you up for revealing their money making schemes,,
I did however catch my horrid misspelling of dihedral repeatedly,, but I was consistant in any case