We measured, studied and built Classic and Flamenco guitars from 1960 to 1973. At first, it was just a hobby, a way of getting sound that was better than what I could afford and better than my first guitar which emigrated with me from Argentina. I built a very iconoclastic first guitar in the very early 60's, played Flamenco with a good friend of mine and later took lessons from Mariano Cordoba until the very late 60's.
During those years we worked steadily toward understanding the acoustic of Classic and Flamenco guitars with the goal of leaving the Lawrence Radiation Lab (now Lawrence Livermore National Lab) to build guitars for a living. This effort was eclipsed in the late '60's by our involvement in the anti-war protests and in the rock music that grew out of it. By 1973, we had our first ad in Guitar Player magazine and were making pickups and, later, electronics for electric guitars and basses.
In 1980 we attended the Catgut Acoustical Society meeting at DeKalb University in Decatur, IL and presented the results of our experiments there. These and the excellent contributions of the other attendees were published by Tim White in his Journal of Guitar Acoustics Vol. 6, 1982 (The Chicago Papers).
Searching for "Experimental Studies of the Acoustics of Classical and Flamenco Guitars" also returns references in the Cybozone Suggested Reading page and in the Novax Guitars website.
Experimental Studies of the Acoustics of Classical and Flamenco Guitars (54.5Mb PDF file - right-click, "Save Content As")
The following are the last 4 pages of the study showing measurements of "length-change-to-pitch-change" ratios for nylon strings and the resulting fret position calculations.
Measuring Modulus of Elasticity along and across the Grain
