....And for tonight's math lesson........

....We will perform a variety of calculations to arrive at the measurement for the the desired height for the shelving brackets that will support the wing spars. There are a couple of things to consider here:

1. What is the comfortable standing height that I can easily rivet the skins to the spar and ribs?
2. Do I need to leave enough room at the bottom of the stand to position the control surfaces (ailerons and flaps) from the trailing edge, and if so, how much room do I need to leave?

A couple of general measurements were taken of the main ribs, the leading edge ribs, the wing spar flanges, and the overall width of the entire wing assembly.

Overall width of the wing according to the wing tip: Approx 60 inches, or 5 feet
Main rib: 26.5 inches
Leading edge rib: 17.5 inches

Total of main and leading edge ribs: Approx 44 inches, plus about 1/16th inch for the thickness of the spar and another 1/16th for the trailing edge spar.

60-44 leaves 16 inches. This is the amount of space I would need to leave on the bottom if I wanted to be able to attach the finished control surfaces to the TE of the wing while they are still in the stands. I think most folks are attaching these when the wing is removed from the stands and placed inthe wing cradle so that the TE is now facing up, making the hinge attach points a bit easier to manage. So I don't think that leaving enough space for the control surfaces on the bottom is a major consideration.

Another aspect of this to consider is that if I do decide to leave enough room on the bottom, a jack will have to reach up that far to support the middle of the wing that naturally starts to sag in the middle when everything is attached to the wing spar until the wing skins are riveted into place. The higher the gap the longer the jack needs to reach to support the rear spar.

When I stood in front of the wing stands, I found that my arm comfortably supports the rivet gun and drill at about 48-50 inches from the floor. Aaron told me that he positioned his support brackets at about 55 inches, but he is also notably taller than I am, so I would naturally expect that from a standing position my brackets would probably be a bit lower than his.

Here is a pic, courtesy of Sean Thomas' RV-7 project, that shows the relative height of his wing stands:

Although I did not measure the height of his support brackets, they also appear to be more along the 48 inch high range. One other consideration for this is a comfortable sitting height when the time comes to rivet the skins on one side of the wing. You want to be able to sit in a chair and comfortably reach from the highest to lowest rivets along each rib while you rivet the skins together.

A few more calculations:

16 + 26.5 (gap for control surfaces plus main rib length) = 42.5.

The leading edge skins will be attached to the nose ribs using the LE cradle, so I won't need to worry so much about  a height that makes it easy to rivet the nose ribs in place, only for the attachment of the LE skins to the main wing spar.

So for now, I think I will settle for a placement of the support brackets somewhere between 48 to 50 inches, or perhaps a bit lower. I will sleep on it and decide tomorrow, and then mark and drill some more holes for the support bracket hardware.