457.5 hours - Reamed the holes in the HS hinges and mounted the elevators -VERY COOL!

There is no better way to spend a leap day during a leap year than doing what I did today, at least as far as I am concerned anyway! This was  fun evening for change. I started by running over to A&A Tradin Post to get a #13 drill bit. I drilled out the hinge holes with this bit first, and followed it with a #12 reamer. I was mostly removing powder coating from the hole, but it did trim some metal as well. Then I trial fitted the mounting bolts in the holesv-everything fit as expected.

Then, after reading pertinent sections of Steve Riffe's builders log for this part of the empennage build, I noted that he had set the rid end bearing measurements on his elevators to 27/32 inches from the spar web to the center of the rod end bearing hole, or the bolt if you prefer. A common practice when a range of measurements is provided, i.e. between a and b, is to split the difference in the range and use that as the target value. In this case, as I stated in my previous posts, The minimum measurement is 13/16, or 26/32 inches. This is how I had set my bearings the other night. The max range on the plans is 7/8 inches, or 28/32.

Steve simply split the difference between the min and max values and set his to 27/32. After reading several recent posts from builders having problems with the LEs rubbing against the edges and rivets of the rear spar of the HS, I decided to adjust mine outward to the same measurement that Steve used for his. I have found that 1/2 of a full turn of the rod end bearing is equivalent to moving it in or out 1/32 id an inch. So I unscrewed each of them out 1/2 of a turn and that took care of it.

Here is shot of my non-scientific bolt centering method for measuring the rod end bearings:

Ya hold the bolt with one hand and measure with the other with the bolt parallel to the spar web and the rod end bearing as straight up and down inside the cutout as possible. Worked very well for me.

Next is the #13 drill bit and the #12 reamer I used to clean out the hinge holes. Sure glad I got this right the first time. That episode with the rudder still gives me nightmares.

Next are some really crappy pics of the marks and pilot holes I drilled in the bottom flange of the rear spar to provide the clearance for the downward movement of the elevators.

I used my nibbler tool to cut away the sections of the flange, and then used some small files to finish the edges and the inside radius. Turned out OK. I will apply some primer and smooth the edges with aluminum oxide sand paper, not in that order of course.

Then I enlisted the help of my son to slide the elevators onto the hinges and install the temporary hinge pins so I could get an idea of several things, including the clearance between the end of the HS and the counterbalance arm of each elevator, the clearance between the leading edges of the elevator and the rear spar of the HS, and the in trail alignment of the elevators with the contour of the HS. On all counts it looks pretty darn good to me.

Next is the alignment of the control horns. I too experienced a slight offset of the contour of both control horns, and it seems that one horn is spaced a little bit further apart from the center bearing than the other one. But other than that everything looks to be close enough to work with, so I am happy with it so far. I will have to put together the right quantity and size of washers on the center bolt to ensure that they fill the uneven gaps correctly, but this is also expected and is normal.

 

 

On this last pic you can just see the forward edge of of counterbalance skin tucked in between the top and bottoms skins on the end of the HS. This is the excess skin that has to be trimmed away. I am hesitant to do this prior to drilling the holes in the control horns for the center bearing bolt, because this seems to keep the elevators in the proper "in trail" position. I will of course also clamp them down to ensure they do not move during the drilling. I will ta to Vans tomorrow to see what the recommended procedure is.

At some point I need to trim away the excess skin so that I can check the range of motion, and also for any binding or rubbing of the elevators against the HS. Looks like I am missing some pics of the tip clearance so I will get those and post them tomorrow. I wish there was a more precise way to confirm the real "in trail" position of the elevators. I will have the same issue when I fit the ailerons to the wings. Maybe a string along the cord line or something like that.

Anyway - it is starting to look like the back end of an airplane at least. VERY COOL!