I was in a Banes and Noble once and found a book strictly about helicopters and to my now regret, I didn't buy it. What I remember about this book is that when you went to the manfacturer, it showed a picture of every variant including that variants prototypes and gave a detailed description of said type. For example, I looked up the Bell 222(my favorite helicopter), and it showed pictures of the prototypes, the A, B, SP, and UT. Flipping through the book, it showed other helicopters in the same regard. It was an amazing book and for the life of me, I can't remember the title!! Does anyone know this book? I remember thinking how it seemed more in depth than Janes in a way since it showed pictures of every variant and protoytype, which is something Janes doesn't do. Thank you for your time.
Dang. Whatever it's called, it sounds like a potential goldmine. Definitely keeping a lookout for it.
So according to this thread, the book appears to be "Bell Aircraft Since 1935" by Alain J. Pelletier, which is part of an aviation series by Putnam.
Scans of the book can be found here: