A MechEng student I knew at university tried to design a new umbrella mechanism that used strips of spring steel that would form helices around the shaft when furled.
IIRC It had two significant drawbacks, a) it had a very high energy barrier for state change, requiring extraordinary user strength, and b) (related) when opening the ends of the strips moved at incredible speed presenting significant threat of decapitation to the user.
IIRC It had two significant drawbacks, a) it had a very high energy barrier for state change, requiring extraordinary user strength, and b) (related) when opening the ends of the strips moved at incredible speed presenting significant threat of decapitation to the user.