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Wing root problems

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  • Member since
    November 2009
  • From: Twin Cities of Minnesota
Wing root problems
Posted by Don Stauffer on Sunday, June 4, 2017 11:36 AM

I have a typical problem on my current project that I think is common to many aircraft modelers.  I find the airfoil thickness of the wing does not match that of the root airfoil, part of the fuselage, that I am gluing the wing too.  No amount of filler really fixes this problem very well

I am beginning to wonder, if by clamping top and bottom surfaces of the wings when I glue them, I am flattening the airfoil a bit.  Next kit, I will measure the thickness when I hold the two halves gently together, and then after gluing.

It seems to me that the kits could prevent problems by having a full rib at the join line, half on the bottom and half on the top.  Many kits have no rib here- and the glue joints are at the leading and trailing edge, and the airfoil is cantilevered between these two points, relying on the (finite) stiffness of the problem.  A stub main spar at this area would also prevent the problem.

What are peoples thoughts on the origin of this problem.  My reasoning comes because I almost always find the thickness of the wing less than the root rib on the fuselage, almost never with the wing thicker than the fuselage.

Don Stauffer in Minnesota

  • Member since
    April 2006
  • From: ON, Canada
Posted by jgeratic on Sunday, June 4, 2017 11:49 AM

I'm not sure what would cause the problem, maybe the quality of plastic causes a slight droop in the airfoil profile, hence it doesn't match the root section of the fuselage?

That scenario is easier to fix than if it were the opposite - just shim up the space between upper and lower wings to match the root?

regards,

Jack

  • Member since
    January 2015
  • From: Tumwater, WA.
Posted by M. Brindos on Sunday, June 4, 2017 11:53 AM

I can't speculate on the cause of this problem, but with careful planning you can always find a solution. 

For example, if the wing is thinner than the wing root you can add spars if it's early enough in the build. You can even do it later in the build process if you don't mind fixing it.

- Mike Brindos "Lost Boy"

  • Member since
    November 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Monday, June 5, 2017 8:32 AM

M. Brindos

I can't speculate on the cause of this problem, but with careful planning you can always find a solution. 

For example, if the wing is thinner than the wing root you can add spars if it's early enough in the build. You can even do it later in the build process if you don't mind fixing it.

 

I agree the spar seems to be a better fix.  Shims between the top and bottom of wings along leading and trailing edges misshapes the airfoil.  Maybe not so bad on older aircraft, but jets always seem to have pretty sharp leading edges, and trailing edge should be sharp on anything.

 

Don Stauffer in Minnesota

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