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Some of the trickier parts to make on the aft fuselage are the splice plates that hold the fore and aft fuselage halves together. As you can see from the plans, there are a lot of measurements, angles and radii to transfer to the aluminum. I cheat by making a photo copy of the part. I always check the quality of the copy by holding the copy and original up to the light. 1/30/00 |
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I then take the copy and stick it on to the AL. In this case I have to make two identical parts so I also used the Homebuilder's Friend (double sided tape or carpet tape) to stick two layers of Al together so I only have to cut once. 1/30/00 |
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Then it is on to the bandsaw and drill press but be careful. If the Al gets hot, the tape will get gooey and the parts can slip. But, if you have a sharp blade/bit and use plenty of wax the Al cuts like butter, well maybe like a very hard T6 butter alloy. 1/30/00 |
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While the parts are still together I use my body blade, files and sanding drums to smooth out the saw marks and clean up the radii. Once the parts are separated it is deburr time. Also these parts call for a chamfer on one edge and it is a lot easier to do that now than after they are bent. With my router table set to its slowest speed it was easy to chamfer the parts with a chamfering bit. 1/30/00 |
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At this point it is a good idea to check your workmanship against the plans and carefully mark the part number. Also, carefully mark whether it is the left or the right part. I'll show you why a little later. 1/30/00 |
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I tried something different this time to bend the 3/16" thick Al. I still mounted the part in my vice and padded the jaws to protect the AL. But rather than just whacking away with my 3# sledge, I first held my plastic tipped mallet against the part right where I wanted the part to bent and then whacked the other end of the mallet with my sledge. This kept me from dinging up my part from the hammer blows and helps me be much more accurate where I place the bending force. 1/30/00 |
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Here is what the splice plates are supposed to look like when fitted to the fuselage longerons. I was not so lucky with all of them thought. 1/30/00 |
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Here is a fun thing to do when you get tired of making progress on your project. First you mistake a dashed line for a solid line on the plan's chamfer detail thereby miss marking your right and left parts. Then you put everything together backward and take a picture of it. Once that is accomplished, you can put that picture on your web site and only then realize what a horrible mistake you have made. On the positive side I have discovered new curse words that will actually remove Sharpie marks better than MEK. 1/30/00 |
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The phoenolic blocks for the rudder cable guides were easy to drill with a Forstner style drill bit. You do want to wear a dust mask though. The epoxy dust is nasty. 1/30/00 |
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The sides, longerons, ribs and cross ties were pretty straight forward to build. Here I am building the cross tie box beam. I am using my combination squares to keep the sides consistent. 2/12/00 |
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Once the box beam is finished, it is amazing how strong it is. 2/12/00 |
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The first step to joining the fuselage sides is to prepare the tail post. You have to have completed the vertical stabilizer before you can go any farther on the fuselage. I started by drilling the tail skid mount to match up with the lower part of the tail post. I then removed the lower part of the tail post from the stabilizer and reattached the skid mount and upper aft longeron mount as well as the spacers that keep everything lined up. 2/12/00 |
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I could then attach the fuselage sides to the tail post, being sure that the sides were square. At this point (and the next few pictures) the fuselage is up-side down on the bench. I know my bench is flat and level so it was easy to use a large carpenter's square to keep the sides perpendicular. 2/12/00 |
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Through the inspection hole, you can see how the upper aft mount ties into the longerons. I did not match drill this part yet. I waited until I the forward cross ties were installed. 2/12/00 |
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My next step was to prepare the sides to accept the forward cross ties. When viewed from above, the aft fuselage is almost but not quite a perfect triangle. It is more of a quadrilateral with the tail post being the shortest side . So you have to make sure that the tail post is not cocked to one side or the other. If the tail post is cocked slightly all the angles will be off and you will have difficulty fitting the bottom skin. I drew a line down the center of my bench that was perpendicular to the end. It was then easy to get the sides even. 2/12/00 |
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Once the sides were even, I began attaching the forward cross ties, being sure that the sides were square vertically to the bench. You also have to be sure that the fuselage is the right width, 40" at this point. This is the left corner of the lower cross tie. The fuselage is still up-side down. 2/12/00 |
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Here is the right corner of the upper cross tie box beam. 2/12/00 |
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A quick check through my rudder cable guides to ensure that all the holes are lining up. 2/12/00 |
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Once the forward cross ties were installed I could install the intermediate bulkheads and cross ties. Here you can see the aft bulkhead. At the top of the picture, you can see the mount for the forward part of the tail skid. At the bottom you can see the hole where the elevator push rod will eventually connect to the elevator control horn. 2/12/00 |
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Here is a closer look at the forward tail skid mount. 2/12/00 |
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Here you can see how the tail skid ties into the tail post. 2/12/00 |
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It was tough getting inside the tail to match drill the upper aft mount to the upper longerons. A 90° angle drill is a must-have here. 2/12/00 |
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Here you can see the mount that will eventually hold the aft part of the horizontal stabilizer. 2/12/00 |
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Here is the cross tie that will eventually hold the forward part of the horizontal stabilizer. 2/12/00 |
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Here I am installing the shoulder harness anchor points. 2/12/00 |
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Now I have the fuselage turned right-side up and you can see the aft shear web. I had to match drill the web from inside while the fuselage was upside down. Then I could drill up to the final size from the outside. 2/12/00 |
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Here you can see the upper and lower aft longeron mounts. 2/12/00 |
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With all the cross ties in place I began fitting the bottom skin. I ran out of full sheets of .025" aluminum because of my experiments with the wing leading edges, so I made the skin from two smaller sheets. The first sheet runs back to the third cross tie and the second from there back to the tail post. The sheets overlap at the third cross tie and I have doubled the number of rivets at the joint. 2/12/00 |
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I cheated when I laid out the skins. I just laid the sheet onto the fuselage bottom clamped it down and traced around the edges. I then removed the sheet and trimmed the edges just slightly inside the lines. Perfect fit. BTW you have to remove the tail skid for this to work. 2/12/00 |
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