Lift Strut attach to Spar
Posted: Thu Nov 05, 2020 8:52 pm
The "original" plans show the brackets on the spar to which the lift struts attach to be something near vertical which puts it aligned with the loads that "intuitively" seem to be applied to this bracket to resist the wings upward deflection. But in analysis the lift strut can really only apply loads to this bracket that are along the lift struts long axis. This is reflected in a few photos I've seen of Piets under construction that do install this bracket at a much "shallower" angle along the spar, aligned with the lift struts. This of course puts a compression load on the spars inboard of the attach brackets and across the center section. These compression loads are there regardless of how the attach bracket on the spar is aligned, its just a matter of if the bracket is loaded along its length or somewhat "across" the straps.
Has there been discussion or "credentialed input" on the matter of how best to align these brackets?
Also, the plans I have show 1/8" plywood doublers on both sides of the spar under these lift strut brackets although I have not seen these in most photos I've found. What is the consensus on these plywood doublers? If used, both front and rear spars?
Thanks for listening
Has there been discussion or "credentialed input" on the matter of how best to align these brackets?
Also, the plans I have show 1/8" plywood doublers on both sides of the spar under these lift strut brackets although I have not seen these in most photos I've found. What is the consensus on these plywood doublers? If used, both front and rear spars?
Thanks for listening