There is a wealth of info on biplane design in the Flight magazine archives. Starting in 1925, there is a section called "The Aircraft Engineer" in the last week of each month with lots of design info. I haven't explored the archives completely, but "The Aircraft Engineer" runs through at least 1938.
http://www.flightglobal.com/pdfarchive/index.html
Enjoy,
Bob
http://www.flightglobal.com/pdfarchive/index.html
Enjoy,
Bob