Alan Adler's Flex program  scroll down Sky and Telescopes resource page for a copy of the program, and to download an adobe acrobat file of the November 2000 article that started this ball rolling.  They are chargeing a little under $3 to download this file.

An engineering evaluation of Bill Kelley's center pull system.

By Toshimi Taki

(Very interesting article (look for "Bill Kelley" article, and evidence that you can make a very simple pulling system under modest appature and modest f ratio.)

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