"There has long been a popular belief that this was actually a deliberate feature of the design, for the purpose of assembling aluminum aircraft without overtig

"There has long been a popular belief that this was actually a deliberate feature of the design, for the purpose of assembling aluminum aircraft without overtightening the fasteners. Extensive evidence is lacking for this specific narrative, and the feature is not mentioned in the original patents. However, a 1949 refinement to the original design described in US Patent #2,474,994 describes this feature."