I have recently read the book: Initial Airworthiness, Determining the Acceptability of New Airborne Systems, by Guy Gratton.
I found it to be an excellent gathering together of the various aspects of aircraft design, certification and testing. This is certainly a "must read" for students of aircraft design, and those who intend to flight test an aircraft.
Each of the important areas of design and certification are discussed, though some at an introductory level (as I'm sure the author intended), and much more detailed study would be possible, should the reader wish to pursue a specific topic.
The reader will finish the book with many of those "why do they do it that way?" questions answered, yet an appetite for more detail too. The book does not center on any particular class of aeroplane, but rather discusses airworthiness aspects of a broad range of aeroplanes, which further helps the reader appreciate differences to be considered.
The author provide numerous "side bars" to explain associated factors, and fill in the background of some information.
Lots of reference information and tables are provided, which will make the book a good reference book for future work, rather than a one time read. I cannot think of another aeroplane design or flight test book I have read which draws together important information as well as this book does.
I highly recommend this book!