The physics of generating lift in a balloon are generally poorly understood by balloon pilots. To an even greater extent are the mechanical and structural forces within a balloon system. The report which can be downloaded from this page is comprised of 2 articles which were published in Balloon Life Magazine many years ago. Both articles were written by William G. Phillips. I have tried to obtain permission to republish these articles on several occasions without response.
Download: Physics of Lift in a Hot Air Balloon / The Forces and Pressures of Balloon Flight - extracted from Balloon Life