BillConnerFASTC
Well-Known Member
Amusing. I looked at data sheets for three manufactures of turnbuckles - Chicago, Crosby, and De Haan. One says the listed swl is based on a design factor, one says safety factor, and the other just says 5 times breaking - avoiding the terms safety and design altogether. They do all put conditions on it - e.g. straight, no impact, etc. - so if it's a design factor, it's very specific to an application, and in the no impact load, a totally unsuitable swl for much automated rigging for example.
Riggers will typically base loading on a uniformly loaded lineset and batten for instance, and use those loads to apply a design factor. What the design factor has to account for is when it all goes haywire, and suddenly the cumulative load of all lines in the set is on one line. Why a static structure may be designed with a factor of 2 and be overkill, and an automated lineset with a factor of 10 and be on the edge in a worst case incident.
Riggers will typically base loading on a uniformly loaded lineset and batten for instance, and use those loads to apply a design factor. What the design factor has to account for is when it all goes haywire, and suddenly the cumulative load of all lines in the set is on one line. Why a static structure may be designed with a factor of 2 and be overkill, and an automated lineset with a factor of 10 and be on the edge in a worst case incident.
