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Yellow Dragonfly Construction Log

Chapter V - Building the Gear Boxes

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Next it was time to make the new plywood ribs. The plans called for 2 layers of 10oz bid to be laid up on each side of each rib; one layer at 45 degrees, and one at 90. I used the rib as a template to cut the glass.	Using my lovely wife's dining room table, I laid the glass on one side of each rib, and allowed it to cure overnight.
The next day, I did the other side. I have found that a piece of glass, waxed with car wax, is an excellent surface to do fiberglass work on. It's flat, smooth, and cleans easily with a razor after cure.	After the ribs had cured, I cut and sanded them to fit. I used my belt sander in a jig for this task. The two ribs that make up each box are slightly different in size due to the wing's taper.
Here is a shot of a test fitting of a rib. This also shows the rough removal of the elevator faring, before the clean up.	Once the ribs were fitted to the canard, they were stacked and drilled. This produces the best accuracy.
The gear boxes were then "dry fit" to see how well they went together, and how well they fit the canard.	After I was happy with the fit, the gear boxes were disassembled and moved back to my wife's kitchen table.
Then I mixed up some flox and buttered the mating surfaces.	With the metal parts covered with flox, I assembled half of the first box.
At this point I only snugged the bolts. Tightening them now would make assembling the other rib difficult. The other side is now floxed.	Once all bolts are in place, I tightened them all down. This drill has a clutch on it that acts as a torque wrench, keeping me from over-tightening it.

The next task at hand is to install foam between the ribs. The Plans call for using a 2 part expanding foam, so I purchased a kit from Aircraft Spruce. I did a very good job with the foam, but I was not happy with the results. I found the foam to be not as dense as the blue foam, and that bothered me. So out came the foam I so carefully installed the week before.

So now I ask you... how do you cut a piece of foam to fit snugly between 2 ribs, and micro it into place, with out rubbing off all the micro while pushing it in to place?

Easy... you make the foam fit nicely, then you cut it in half on the diagonal, forming 2 wedge shaped pieces, that when inserted one at a time, actually push out against the ribs, as opposed to sliding past.

Here are the 2 gear boxes, fitted with the foam reinforcement blocks cut on the diagonal. This is a test fit. The wedges were then covered with a generous amount of micro, and slid into place.	Once they were in place, tape was wrapped in different directions to keep the wedges in place. Look close and you can see the diagonal.
Since it was very cold out in the garage, I decided to use the oven. Placed on an old cookie sheet, and with the oven turned down as low as it would go, everything turned out real well.	Here's the finished product, ready for installation. Again, looking closely, you can see the diagonal.

Esse site foi ideia de Patrick Panzera de Hanford California EUA.

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