Maximum rotation degree for torsion springs?

[Ildar]

According to Michael Lewis

Alan Wilkins has mentioned it before he did (JRMES 6, 1995, p. 44; JRMES 11, 2000, p. 99).

Digby Stevenson managed to make some sinew rope, but never published any details.

This is not so. He gives a short description of the process in the article "The manufacture of sinew rope" (Journal of the Society of Archer-Antiquaries 40, 1997, p. 16). The process is very similar to making of sinew bowstring by modern traditional bowmakers (the video can be easily found on youtube). One should also consult his BA dissertation (which, unfortunately, is not available to me): "Heron's cheiroballistra, with an appendix on the manufacture of sinew rope", UCL, 1995.

P.S. J.E. Gordon in his famous book "Structures or why things don’t fall down" specifies the working deformation of sinew as 8%.