The setup is very simple. One important notice: apply tension/load with system built of non-stretchy materials. In my case steel cable connected to hunters’ digital scale and to dyneema wrapped around the plank.
I used headstay adjuster to precisely apply load. The laser range finder fixed to the tripod was delivering precise continuous reading of deflection. Reading of deflection was taken after every 10kg load added from 0 to 120kg.
Simple graph below shows interesting results: