Being close to failure isn&#x27;t a requirement for visibly bending. For example, see wire rope or cloth. Anything very long and thin can flex a long way without much strain on any individual part of it.<p>Low FoS yes, but even if you doubled it to 3, you&#x27;d still see the wing tip moving - only half as much.<p>Truck trailers are also very soft in torsion. See an empty one go over a big bump and it&#x27;ll visibly twist. Not close to failure, just not very stiff.