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 Sailplane Construction Project Session #145

Comet Sailplane Project
During the construction of the Sailplane, I have been using temporary wooden Maple motor mount spacers to make room for the metal fuel tank behind the McCoy 60 and hold the forward landing gear strut in place as shown below.
I have now replaced these temporary spaces with machined aluminum spacers. Even though the aluminum spacers fit perfectly, they were hard get on and seemed to bind when tightened down on the firewall because they were slightly tilted. Worse yet, when removed they caused the 1/8" landing gear wire to leave a slight indentation in the firewall. I checked the depth of the 1/8" groove in the aluminum spacers and they was precisely 1/8" deep. Something was definitely wrong that I did not understand.
I sat and looked at the installation for some time last evening and then it finally came to me what the problem was. The two .010" metal landing gear straps shown below used to attach the 1/8" wire to the firewall was causing an .010" standoff from the firewall at the apex of the bent wire. However, the aluminum spacers were machined so accurately that when they were tightened down, the slope of the wire was causing binding and the wire to mash into the edges of the firewall (DUH). The simple fix was to make two .010" metal back up plates with the same foot print as the spacers to go between the landing gear wire and firewall so the wire would remain parallel to the face of the firewall as shown below.
With the .010" back up plates in position, the aluminum spacers went right on and tightened down smoothly with no binding or indentation in the firewall as shown below.....................Tandy

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