Hello all,
A group of us have been finishing the build of a Cygent SF-2A that was donated to our eaa chapter. The builder passed away before finishing it. Needless to say we found many parts that had mistakes and we have been spending a fair amount of time fixing them over the last year. We are now to the struts and the ones built by the builder have some serious issues. One is 1.5" longer than the other and it is not adjustable in any way. Also when we replaced all the wing attachment brackets and strut fittings we found that even if the struts were the correct length they still did not fit. This has led me to redesign the struts in a way that allows for some adjustment. Since the wing is swept forward the struts are swept as well which is why I incorporated a knuckle with 2 axis of motion at the fuselage attachment point. At the wing attachment point I have a high load spherical ball joint and 2 spacers to allow the bolt to align itself as needed with the wing fitting. The ball joint gives me some adjustment in 3 axis as well as I can adjust the length of the strut. The ball joint has a 3/8-24 threaded shank that is threaded into the fitting bolted in the end of the strut. My only concern is in tension are the threads strong enough to not pull out of the fitting? I can helicoil the mating thread if needed if that will help. All the bolts attaching the fittings to the strut as well as strut to wing and fuselage are 5/16 AN bolts.. The strut is a Carlson aircraft aluminum large strut and its total length installed is around 88". Without having to go the FEA route and more the TLAR route, how does this look?
Any suggestions will be greatly appreciated.
Marc
A group of us have been finishing the build of a Cygent SF-2A that was donated to our eaa chapter. The builder passed away before finishing it. Needless to say we found many parts that had mistakes and we have been spending a fair amount of time fixing them over the last year. We are now to the struts and the ones built by the builder have some serious issues. One is 1.5" longer than the other and it is not adjustable in any way. Also when we replaced all the wing attachment brackets and strut fittings we found that even if the struts were the correct length they still did not fit. This has led me to redesign the struts in a way that allows for some adjustment. Since the wing is swept forward the struts are swept as well which is why I incorporated a knuckle with 2 axis of motion at the fuselage attachment point. At the wing attachment point I have a high load spherical ball joint and 2 spacers to allow the bolt to align itself as needed with the wing fitting. The ball joint gives me some adjustment in 3 axis as well as I can adjust the length of the strut. The ball joint has a 3/8-24 threaded shank that is threaded into the fitting bolted in the end of the strut. My only concern is in tension are the threads strong enough to not pull out of the fitting? I can helicoil the mating thread if needed if that will help. All the bolts attaching the fittings to the strut as well as strut to wing and fuselage are 5/16 AN bolts.. The strut is a Carlson aircraft aluminum large strut and its total length installed is around 88". Without having to go the FEA route and more the TLAR route, how does this look?
Any suggestions will be greatly appreciated.
Marc