George -
A much and long discussed question and topic of discussion. I have some answers (in writing - formal engineering report) and some that can only be described as "oral history" and personal experience. I'll be glad to share what I know and what I think, but would prefer to do this via phone - I don't have much endurance for typing at length any more!
Thank you for the query!
William E. Lockridge
Principal Research Manager
Selma Research Project
9537 Goldsmith Lane
Mint Hill, NC 28227
(704) 545-0083
welhunter@aol.com