July 25th, 2007
Started Rudder Construction - Right
Tonight I got a start on the rudder. The first thing to do is make the rudder stiffeners for the left and right skins. The skins are really thin .0016" aluminum. By themselves they are flimsy but after the stiffeners get attached they become much stronger. First of all I had to remove all of the blue plastic from the R-915 stock pieces. I am using a scrap piece of MDF board to lay the skins on. I will then match drill everything right through the board so I don't harm my work table.
A lot of people seem to have difficulty getting the holes to line up between the R-915 stiffeners and the skins. I am going to show you my process that actually works pretty good. I was able to make all of the stiffeners in a few minutes using this method.
I work on one R-915 at a time starting with "A" and working up to "H". I mark each cut using a permanent marker using the plans as a guide. Once I made 2 or 3 of these, I didn't need to look at the plans any more. The material marked with "X" gets removed.
I started each R-915 first by making the cuts at the trailing edge end. I use a rule to mark a straight line between the two notches in the angle stock.
Then I mark the end cuts between the notches.
At first I used my band saw but I later switched to the shears. It was much faster for me to just cut them by hand. The cut was smoother that when I used my band saw and a lot less noisy. I had less work cleaning up the edges that way. I used both the left and right handed snips.
One end is complete.
Then I laid the R-915 on the skin and lined up the holes. You can see it is too long.
Mark where the cutoff will be after the last hole. Make sure to leave enough material for the minimum edge distance for the rivet.
Notice on the vertical portion of each R-915 the the cut is slanted away form the end.
After I cut all the pieces, I ran them all through the scotch brite wheel to clean them up and round all the corners/edges.
Clecoed in place and ready to drill. (I added more clecos that what you see here. You can see the skin sagging down beneath each stiffener)