July 5, 2009 Tail Construction.ppt

Progress continues on the tail kit over the long July 4th weekend, during which I've got lots of time to work on it.

I'm using digital photos fed into powerpoint to document, and I've attached the slide show for today's work. The large file size is a result of the many photos that are included.

I started today by laying out the horizontal stab forward spar (with doublers previously clecoed on) and the two rear ribs which attach to it at the 160 mm positions to either side of the spar centerline.

I marked rivet lines on the forward flanges of the ribs, and then placed the ribs into their positions to test fit, making sure that the rib flanges faced outboard. They fit just right when positioned correctly, with the curved edge of the rib matched to the lower doubler and the flat edge of the rib matched to the upper doubler.

Then I focused on getting the first rear rib positioned just right and clamped it into place. It was easiest to do this by placing the whole assembly upside down so as to take advantage of the flat upper edge of the stab. The lower edge is not a 90-degree angle, but instead is angled to follow the curve of the bottom surface of the stab.

I placed the rear rib into position and sighted through the top of the four existing holes in the spar to locate the rivet line which I had drawn on the forward flange of the rib. I found the rivet line and carefully drilled through the existing top hole, #40 bit, into and through the rib flange and clecoed it.

Using that top clecoed hole as a pivot, I then used my square to square the rib to the spar, confirming by sighting the rivet line drawn on the forward rib flange through the existing holes in the spar. Once squared up, the rivet line was visible in the exact center of the existing holes. I drilled the bottom hole in the row of four existing holes through the spar/doubler and into and through the rib flange, and clecoed.

Then I drilled the two remaining holes in between the top and bottom, and clecoed.

Then I confirmed by examining the other side of the spar that the holes had been drilled into the forward flange of the rib with sufficient edge distance.

I followed exactly the same procedure to drill the holes for the other rear rib.

The same method was used to locate the forward rib at its position 60 mm pax-side from the centerline of the spar/doublers.

After that, I made the brackets which are used at the end of the forward spar to attach the ribs that go there. These brackets are made from the supplied ell-angle stock, and I measured the width of the spar at its ends and determined that a bracket 100 mm long would be just right. Two of these brackets are needed; one for each end of the spar.

I marked 100 mm lengths on the ell-angle stock, rough cut them out with snips, and then cleaned them up with a steel file.

To locate the rivets, I measured 10 mm from the ends of the upper doubler/spar and marked a spot for the rivet in line with the other rivet holes on the doubler. Then I drilled through the upper doubler/spar at this point.

Then I clamped the bracket into position and drilled through the hole I had just made in the upper doubler/spar at the 10 mm location to go through the bracket at that point, and clecoed.

Next, I measured 10 mm from the ends of the lower doubler/spar on that end and made a mark for a rivet in line with the existing rivets there. I pivoted the bracket out of the way to drill this hole, but the bracket could have just as easily been removed.

Once this hole was drilled, I repositioned the bracket in its place (with the other end clecoed) and carefully drilled through the hole in the lower doubler/spar into and through the bracket, and clecoed.

I repeated this exact same process on the other end of the spar to locate and drill the rivet holes there.

I wasn't sure exactly how many holes are supposed to be located between the top and bottom ones on the end bracket, so I left them with only the top and bottom holes for the moment.

I cleaned up, put up, and was done in about an hour and 20 minutes.

Check back soon for more updates, or view the slideshow for photos.