Airplane Design Part I : Preliminary Sizing of Airplanes

It was interesting and useful for me, a curious hobbyist who likes to design airplanes in X-plane.

Very good reference book.

The data in this book goes back to the 1930's, but for an undergraduate level book that is supposed to give you an understanding of the design process behind an airplane, it's not so bad. It does a great job of explaining most of the variables, although there are some "referenced materials" that are extremely difficult to find. However, this book, and all the preceding versions cover the airplane design process in excruciating detail, so hopefully by the time you've gone through them all, you will be able to design a fully functional, statically (and dynamically) stable airplane that meets all of the FAA requirements.