Wing Skin Stiffeners


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Last Update:

May 12, 2011



Here’s the stiffener blank with the wing rib form block. I decided to try the method outlined in the BearTracks newsletter to form the bend with heat from a torch.

To establish the correct bend you screw the stiffener to the wing rib form. Here the stiffener is captured under a large washer screwed to the form. I left the washer just loose enough to let the stiffener expand as it heated up. I drilled a hole in the fore end of the stiffener to attach it to the form.

You can see that it has quite a ways to bend to mimic the airfoil shape.

Here’s the fore end screwed to the form blocks. I used a finish washer to distribute the load around the hole. You can also put a little fiberglass insulation material under the stiffener at the two ends to help keep your form block from burning.


The stiffener is pulled down to the form and ready to be heated with the small torch on the table.


Heat the stiffener evenly by moving the flame slowly up and down the length. Put the torch closer than shown here. Use the blue cone to direct the heat. I was supprized at how much heat was needed to make the stiffener take the required bend.


First two stiffeners done! This method works very well. Just keep checking the bend by unscrewing the fore end a little to see if it is still under tension.

Shawn Burns posted a tool and method for making joggles. The tool is simply a piece of steel the appropriate thickness with a slot cut into an edge. Round and polish the cut edges to keep from scratching/cutting the aluminum you are going to joggle.

Above the tool is the stiffener before joggling.


One side joggled and one to go. Place the tool on the flange and squeeze the tool and flange in a vice to form the joggle. Be sure you place the tool ‘under’ the part of the flange to be ‘raised’

Worked great. Thanks Shawn.


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