Chris Heintz's book makes many references to Kuhn's Diagonal Tension Factor. I understand that Kuhn wrote an entire structures textbook. I'm trying to dig through to find any curves that match the one on page 185 in the 3rd edition of Heintz's book. Can anyone tell me where I can locate this formula? I have found the NACA report (https://ntrs.nasa.gov/api/citations/19930082135/downloads/19930082135.pdf) on curved webs (Chris used it for flat webs, e.g. the spar). I have also searched the site and have found many references to Kuhn's book but no direct discussion of the formula. At the moment, I'm interpolating using regression to get me "close enough" for spreadsheet calculations.