I met the man 3 years ago when a gun collectors organization, the Ohio Gun Collectors Association, had him as a guest speaker. He was quite a storyteller. He told us he had been present during the field tests of the Sherman tank along with some other Generals and during the field test Patton wanted to give it a drive. Well Patton was driving the tank and in the field had been an old shack. Patton was going to run the shack over so he went for it at full speed and ended up going right into the ground. The shack had a basement and he sunk right into it. They had to clear all the debris off the tank and Patton comes out of the tank embarrassed but too proud to say anything about his screwup. Anyways, I have a copy of his autographed book.
http://www.ogca.com/History.htm There is a mention of him being present at this event on the OGCAs website. Tibbits also didn't have a high opinion of the other B29 pilot Sweeney who dropped bomb two. Apparently Sweeney messed up and missed the primary target so he hit Nagasaki instead which was target B.