Saturday, February 13, 2010


More Tailfeathers:
The horizontal is almost finished. I still need to add the bushings for the brace wires and of course attach it to the fuselage.



For the control horns I used .090 thick 4130 instead of the .063 (the plans say .065 but that is not a thickness made). The way these are made with no flanges, I just felt like I wanted a little more thickness in the pieces. The 1 ounce or so weight penalty is an acceptable trade off as far as I'm concerned. I'm sure the stock thickness is just fine, I just feel more comfortable with this. BTW, the odd looking bushing is just something I had laying around to allow me to use a bolt that was a little too long.







Propped up on the fuselage.






Sunday, February 7, 2010

Tailfeathers cont:

To lay out the curve for the elevator tip I used a welding rod and curved it to what I thought looked right and then traced the line. I usually use a flexible yardstick, piece of aluminum etc. but today, the welding rod was handy so I used it.



After curving the 1/4" x .035 trailing edge tube I welded it on the side toward the center line and to the elevator spar on the outside edge. I flattened the elevator spar using my vise and a couple of pieces of heavy steel. I then touched it up with heat and a body hammer.


The plans call for the 1/4" tubing here on the counterbalance. Since mine is larger than the plans I felt I needed something a bit more substantial so I used a 7/8" x 035" tube. The extra 2 ounces of weight is ahead of the hinge line so it will only help with balance.



I notched the end with my cutoff wheel and then heated and used a hammer to form the end. You can see that the other side has not been formed yet.



I also departed slightly from the plans here as well. The elevator ribs call for the 1/4" tube to sit right on top of one another. This would entail two very long tapered cuts on the 1/4" material which would have been problematic. It's very small and would be hard to hold for sawing or grinding. What I did is simply let the tube be side by side at the trailing edge and be in line at the forward edge.



I made all the ribs on this ultra simple jig made of the usual finish nails in plywood and tacked them together. Then its a simple matter to use the bench grinder to form the ends.



Here are the ribs installed. Don't forget to use 5/16" spacers (I used bolts) to make sure the centerline of the trailing edge is in line with the centerline of the elevator spar.



I still need to add the two braces in the elevator. The 1/4" tubing really moves around a lot when you weld it and may be a tad small for the application. I've never seen this small of tubing used and I think that 3/8" might be a better choice but I would hate to add the weight behind the hinge line. Here is one half of the elevator basically complete except for the two mentioned brace tubes.



I welded the tail ribs together for a couple of inches just to make sure they are secure.