Some time after the plane flew with the biplane wings Dad built a fake Lewis gun and mounted it on the wing center section. Rather than take the plane apart and uncover the center section he built a mount for it which could be bolted on to the assembled plane. The tubes support the light weight gun. The wires prevent the propwash pushing it back. It works fine.
I got to thinking that the tubes and wires are probably disturbing the air flow such that there is little or no lift from the center section. As a result I decided that while I had the center section uncovered I'd make a different mount. I have no interest in something as complicated as on the SE5 since the gun doesn't work. I would like to make one that fires acetylene gas some day.
I decided to mount the gun to the spars with little "A" shaped mounts. The forward mount picks up the old clamp around the barrel and the aft mount picks up the bolt hole in the gun, from the old mount. As a result the idea is the same for both mounts but the forward mount is taller than the aft mount.
I bent the brackets with 30 degree and 60 degree bends. to get the mount hole on each half the same height I made the hole in one, clamped them to the work bench, and punched the second hole. Then the second can be cut to length and the end rounded like on the brace wire clips in the prior blog post.
The gun sets nice. I made "L" shaped brackets for each side of the center rib. They are riveted to a piece of aluminum using the rivets which hold the nut plates to the bottom of the supports. The aluminum gives the brackets some stability and a place to attach the fabric covering.
The nut plates allow the mounts to be screwed on after covering.
The supports are the same, forward and aft, except the bend angle is slightly different because of the rib contour.
The supports are each bolted to the spar with a 3/16" bolt. On the rear spar they go all the way through the trailing edge with a little counter bore so they don't show through the fabric covering.
For the forward spar 2 small holes were sawed into the aluminum leading edge to get to the nuts, and then covered with aluminum duct tap.
The finished mount should work fine and may even be slightly lighter, a nice bonus.
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