From time to time, I'll receive e-mails from people asking me for advice on some good engineering books to use for aircraft design. Dan Raymer, a well respected engineer, already has a list on his website. It's a pretty long list, though, and would take a while to build up that collection. So, I figured I would recommend the ones that I use most often. The following three books are ones that I use on a regular basis that are generally useful for all aircraft.
Aircraft Design: A Conceptual Approach
by Daniel P. Raymer
We referred to this as our aircraft Bible back in school. It covers everything from layout to weight estimation to control loads and more. It also has a good deal of empirical data. I have the 3rd edition, and I use it almost weekly.
Introduction to Flight
by John D. Anderson
This book starts of with the fundamentals of aerodynamics, and moves on from there, to subjects such as performance, stability, and propulsion. There are also many nice historical details thrown into the text. Between this book and Raymer's, you can usually figure out just about all you need to know. While Raymer's a little more practical, Anderson's more theoretical. Plus, this book has a chart of the standard atmosphere included as an index, which is very handy. Anderson was also one of my favorite professors, but talking to students from other universities, they all used this book, too. I've provided links to the hard cover & the paperback, below. Buy the paperback if you need to save money, but this is a book I use often enough that I'm glad to have the hard cover.
Theory of Wing Sections: Including a Summary of Airfoil Data
by Ira H. Abbott & A. E. von Doenhoff
While I use the theory section of this some, it's most useful for its indices, with definitions and Cl & Cd curves for many different NACA airfoils. It really is a classic text that every aeronautical engineer should have.
You'll also need to handle structures. Personally, I use Mechanics of Materials by Beer & Johnston as my reference on that, mainly because it was the text from the class I had. I really don't feel as strongly about that as the three books listed above. I'll also borrow books from co-workers, which are very good, including Mark's Standard Handbook for Mechanical Engineers, Machinery's Handbook, and Roark's Forumulas for Stress and Strain. Those three are very handy references, that I would probably buy for myself if I couldn't just turn around and borrow them from my coworkers.