More about wing stand bottom support brackets......much, much more......

IN my previous post I mentioned that I was going to use clamps to avoid measuring and drilling more bolt holes in my wing stands. The Vans plans do not elaborate on the bottom support brackets, nor do they show a detailed inset of the assembly for the bottom bracket like they do for the top ones. Well since the last blast of winter moved out of town, for some reason I changed my mind and decided to proceed with all the necessary cutting, drilling, fitting, and leveling of the bottom support brackets. Call me a sucker for punishment I guess.

Part of the reason for doing this is to document it for other builders. I could find pictures from other build logs showing how others have done this, but I never see any details written about how the did it. That would leave one to believe that the procedure may be so simple that it is obvious, but I say that could not be further from the truth.

For the bottom brackets on the tip end of the wing, you have to deal with the proximity or distance of the ribs and skins to the lower angle bracket, the overhanging skins from the tip rib (about 1/2 inch), and ensure that the wings are mounted on the stands in such a way that the the lower tip bracket can be mounted to the tip rib without interfering with the overhanging wing skin at the trailing edge of the had to reverse the right wing on my stand because of this.

Anyway, a whole lot of tools and measurements and drill bit changes and fitting and cutting and so on later, I managed to get the bottom bracket fitted exactly the way that I wanted it. The only less-than-desirable thing was the 3/16th inch #10 hardware that I had to pick up from the specialty hardware store in my area to attach the angle to the tip rib, since the big box stores don't really carry bolts in this size at all. I ended up getting some screws that are threaded all the way to the pan head, and I really need something similar to the tank attach bracket bolts, but they are not quite long enough for the job.

ON to the pics.I started by using my top brackets as a template for the length of each bottom bracket. I measured and cut them from some existing 2 inch steel angle that I still had lying around. Note that I am using 2 inch angle on the bottom brackets, which is necessary for me because of the 1.5 inch angle I used for top, combined with the 2 inch short angle pieces that attach to the rib and set over the top of each top support bracket. I did this to add the necessary gap between the extended skins that exceed the flange of the final rib to act as the attach points for each wing tip. I used bar clamps to secure the angle to the bottom of the wing stand,and quickly discovered how close to the bottom wing skin the angle would come (less than 1/8 inch.) I also had to check it for level since I was going to drill another bolt hole to attach the angle to wing stand. It all had to line up correctly to avoid interfering in a number of different ways.

I measure and drilled the 1/4 inch hole in the angle bracket as shown below:

This hole is 2 inches in from the end, which should center it along the 4 inch side of the 2x4 steel post.  the Perhaps I should have started with the step where I drew the reference line across the top of the angle after leveling it against the post and positioning it the way I wanted it. Here is both the inside bolt hole that was transferred by an ultra fine sharpee pen from the hole drilled in the angle. This made marking the first bolt hole rather simple.

I then used my straight edge and clamped it along the reference line so I could use my tape measure to measure the line from the top of the post down,which is the most common area to use to ensure the measurements are transferred accurately over to the other side of the post.

THis next pic shows many things. First is the line transferred to the outer side of the stand, and the bolt hole and bolt that were ultimately drilled and secured along with the angle to the post. I should also point out that I ground down the edges of the steel angle and smoothed them on my scotch brite wheel. I don't want any of the heavy metal marring up the airplane parts so this was essential.

Next is shows how closely this angle comes to the top and bottom skins, and how level it aligns with the rear spar and rear rib flange of the tip rib. It also shows the sharpee outline of the small aluminum angle I used as the attach angle to the rib. It mounts to the steel angle and then also to the forming hole in the rib. It also shows the level on top to ensure that everything was in alignment.

Here is another view

For the attach angle I used some scrap 1.5 inch aluminum angle from HD aviation department. THis is the same angle that was used as a backer plate to countersink all those pesky tank attach nut plates to the main spar. I cut it to size and smoothed it with the scotch brite wheel.

Next came the 1/4 inch hole in the attach bracket which I just eyeballed and decided where I wanted to drill it.

Then I transferred the mounting hole from the attach bracket to the support bracket:

Then I removed the steel support bracket and drilled the hole. THen I was able to take a short 1/4 inch bolt and attach the two angles together.

Then came the fun part of figuring out how to transfer the exact measurements of the location of the forming hole in the rib to the other side of the aluminum attach bracket. I removed the attach bracket, ensured the support bracket was level, and used my straight edge to mark a line on the front and back sides of the forming hole on the rib, and I extended these lines above the top marks for the attach angle so they could be seen after the attach angle was placed back on the support bracket against the rib. I then transferred the lines from the rib to the attach angle and then took the final measurement from the top edge line down. From this I had enough dimensions transferred to the attach angle so that I could drill the necessary 3/16th inch hole. I was very pleased with the alignment:

I put a piece of gorilla tape on the back side of the attach angle so that it will not mar the side of the rib, and then used the 3/16th inch hardware to attach the angle to the rib. It fit like a glove (thankfully). I even was able to insert my arm through the next to the last lightening hole to hold a nut driver on the nut on the inside of the rib that holes the screw in place. Everything is secured nicely, and it only took me most of the day to get it all done.

One down and one to go......