Wing Mounts

[John Harmon]

Hi everyone. I have a question about XL plans page 7A. There is a 1/16" gusset that welds between the cabanes and the square tubes the wings mount to. My question is how many of these are required? Is there 2 or 4? One on each side of the wing mount tube? or is one  per wing mount sufficient?

[John Harmon]

95 views,  and no one knows? Oh well...guess I'll  have to wing it.

[CHARLES DEBOER]

I used just one piece of 1/16" 4130, based on the fact that you have to move the two mounts fore and aft to align with the wing fittings installed on the wing spars (dependent on the accuracy of the cabane structure) and some photos of Joe Spencer and Sam Buccanan projects.  You could only weld it to one side of the cabanes.  Rocky Dog (Joe Spencer) built an UL and wanted to improve the wing mount and posted his mod on the old web site which influenced the XL design ( I think not sure ). His mod only has one plate/gusset for each mount.  Search the old web site. Not sure if it is still there.   I must declare that my XL has not flown yet and I have never built an airplane before.  But, I think that 1/16" gusset is plenty strong when you consider that one wing mount is carrying about 1/6 of the load with the wing struts carrying the rest.  (575 X 4Gs = 2300 / 6 = 383.3 lbs. per attach point )

[Nical]

On E-20 the forward root mount has  2   .040. 4130 gussets to run the load path down the vertical tubes. Aft a small gusset transfers loads to the cabane tube. Aft of the square tube, .040 4130 gussets run the load path down the vertical tubes. Aft different because square cross tube slightly forward of vertical tube centerlines.
   Structurally huge overkill but as close to correct load path distribution as I could work out.
    E-20 is assembled for strut length and general final cable lengths etc etc.
    Wing covering in a week or so. Flying next early Spring. This aircraft is #11 for me. Homebuilding is addictive!
     Nick L.

[Will Weidner]

This is a photo Steve Kiblinger posted on the old site.  I think its of Leonard's prototype.  Mine looks a lot like this.  I built my cabanes exactly to plans, and transferred the fore and aft distance of the mounts from the wing ribs.  As a result, the 1/16" gussets align somewhere within the edges of the 1/2" square tubes.  I split the difference so they hang over the gussets the same amount front and back.  This also looks like what Leonard was trying to convey on page 7a.

[John Harmon]

Thanks guys.

[Will Weidner]

John, glad to hear you're back at it.  Look forward to seeing some progress pictures.