Riveting nose rib wing skins

[Gary Wallace]

Has anyone tried riveting the wing skins starting with the bottom of the nose ribs while the top skins were lifted up, then after nose ribs were riveted down to bottom of nose ribs, cleco skins down to top of the nose ribs, main spar and over ribs to buck remaining nose ribs through lightening holes in main spar??

[Glenn Patterson]

The skins were clecoed on to the main ribs and front spar spar then we put MDF reinforcements on the ends of the nose ribs. The reinforcements kept the tips from buckling and then we ran a length of wood through the lightening holes and clamped blocking on each side of the rib to keep them in place. The tip reinforcements we made by flush cutting MDF to our MDF wing pattern. We ran ratchet straps over the around the wing and pulled the nose skin tight over the nose ribs. Blocking was put between the ratchet straps and the rear spar to protect the spar. This has to be done with care to get a good wrap and not over tension. we had a 4 ft piece of 1x2 that we ran under the ratchet straps. We pushed the board up just above the rivet line to be drilled to hold the skin tight to the rib. The 1x2 pushes any slack out of the skin ahead of the row being clecoed. We worked from the top side main spar over the top. We had our skins clecoed along the main spar before we went over the top. Some say to do the main spar last so that the wing can be squared. If the spars and ribs are not square before the ribs are clecoed in it will never be square. Make sure the wing spar rib assembly is straight and no sag in the spars before doing any skinning. We put vertical boards up from the floor the the rear spar to lift out any sag that occured. My point is that you get the skins flat and taut then you can cleco from rear spar up to main spar then along the main spar before skinning over the top. The reason we did the spars is that once all the ribs are clecoed that there is no way to adjust squareness as the diaphragm strength of the aluminum skin will not allow any adjustment. It is like drywalling a wall. The wall studs have to be lined up & where they need to be and once the drywall goes on the studs are not moving. Same principle applies to ribs and skins.

We did as you said that we reached up through the main spar to buck the ribs. I had an argument with my partner on the how to to the nose skin. He wanted to cleco the skin to the main spar on the underside to secure the first skin then back fill the nose rib holes. I argued that we would push a wave as we clecoed and worked the skin tight with the 1x2. To make my point we drilled a hole in the skin excess that was in line with the rivet row on the underside of the main spar. We worked the skin over and the hole crept about 1/4-3/8 as we pushed the skin tight over the top and down the backside. I have attached a couple photos.

I did a write up a few years ago on the process for reinforcing the wing tips for skinning the wings. The skins are tight to the wing nose and gave the exact profile for the leading edge. My Beartracks write up is on another computer at a house we are moving into. Finally bought a house with a decent garage..

One foot note is that we were not happy with the space between the flap & ailerons. We drilled out the rivets & slid a strip of aluminum between the top & bottom skins and the rear spar that extended the skins to create gap seals or closures between the aileron and the flaps. There is a gap of slightly more than 1/8" through the range of motion of the control surfaces. Then we riveted the skins and skins extension to the rear spar. My partner told Bob Barrows about our steps to close the gap and he thought that was a good.

The full set of Beartracks along with Erb's and Newtons manuals were invaluable guides to our build process. We could see examples of how to do various processes in the Beartracks and with the manuals to come up with a processes that work.

[Glenn Patterson]

I found the presentation that I did on building a BH wing from scratch today on a thumb drive while looking for a resume. I trimmed both sides of the document to leave the section showing skinning over the nose ribs. This illustrates the process better than the written description. This is one builders method and others may chime in as well to give you some ideas to formulate a process,

[Gary Wallace]

Thanks Glen

[Glenn Patterson]

You are welcome. I hope it was of some help.
Glenn