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Old 11-12-2008, 11:48 AM
  #102  
richbran
 
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Default RE: SkyMaster MB339 Build Thread

The next I tackled was the wing fixation.
As I have chosen for a combo of sub-D pins and the quick disconnects for air, I found out the fuse slightly compressed in that area when pushing the wing against the fuse. The idea the wing would open up a bit during flight under load and pressure on 2 of the air hoses, scared me! I just HAD to make a solid connection that would pull at least that area together. Check out the pics where You can see the slit BEFORE and AFTER the mod, bolted in place.
The easiest way would be bolting it from the inside, but You cannot reach that area because of the fuel tanks.

This is the way I solved it.
Right in between the Sub-D's and the air conn's I drilled a 5mm hole, with wing installed, through fuse and wing root. From a piece of electrical installation flexible tubing (am one of those guys that NEVER throws away something, ) I made an angled tube.
Put a 5mm thick plywood insert in the side of that tube that has to be glued against the inside of the wing root rib.
Made a hole in the wing underside to fit that tube, at some distance from the root, but not PAST the first rib!
Then I made u tool which was flexible and included a Hex ball on top.
I found a never used spring type of hex nut tool shaft and cut off both thick sides, just left a little "meat" to be able to drill an undeep hole to accept the (sawed off) ball side of a hex wrench. (Silver) soldered it to that spring, as well as the left over part of the wrench. Now I had a tool that would bend accordingly.

Jiggling the lot into place with the help of a 5mm guide took a while to figure out.
The front side of the tube contacted the inner side of the root rib now, and I had to glue it. I drilled an extra small hole in the wing underside, right under the area and dripped some superglue in it. Then slipped an hex nut of required lenght in the tube.


It worked almost right from the start, the only mod I had to make was to beef up(wider diameter) the last part of the tool, it would initially not "find" the hex nut hole, because the bend in the tubing presses the tool'front side off-centre. Now the tool's top part fits snugly, and leading the ball right to the nut.
Also here some green touch up needed, as soon as I have it.

OK, some might shy away from making an opening in a neatly built wing, but I reckon the added safety greatly outsells that little price.
Hope the pics will explain more...

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