I've found the following books useful in learning about rocket science and creating this site. The list is far from exhaustive, as there are many other good textbooks.

Rocket Propulsion Elements
Author : GP Sutton, O Biblarz
Publisher : Wiley
The definitive introductory book on rocket propulsion. A basic grounding in physics is required. After reading this I felt inspred to have a go at designing and building a liquid fuelled motor. If only there was more time....

Missile Structures Analysis and Design (Out of print)
Editor : EF Bruhn.
Publisher : Tri-State Offset Company
A good introduction to the structural design of launch vehicles. The book descibes methods of load analysis for rockets and missiles, allowing identification of likely points of failure. The same principles can be scaled down to large HPR. It dates from the 1960s and is based on launchers of the moonshot era. As a bonus, it has some interesting drawings and data for anyone researching the Saturn V.

Mechanics of Flight
Author : AC Kermode
Publisher : Prentice Hall
A descriptive introduction to aerodynamics. Light on maths and very readable, it explains the basics of subsonic flight before describing the aerodynamics of transonic and supersonic flight. A very good first book for someone dipping their toe into aerodynamics for the first time.

Mechanical Science
Author : W Bolton
Publisher : Blackwell Science
This book is aimed at HNC/HND students and introduces the basics of mechanical engineering. It coveres some areas which are useful in rocket design, particularly the chapter on cylindrical shells. It also introduces some of the basic ideas of structures from 2 materials, useful in calculating the stiffness of, for example, a glassed airframe.

Spaceflight Dynamics
Author : WE Wiesel
Publisher : Mc Graw Hill
An excellent book on the dynamic behaviour of space vehicles. It intrduces all the fundamental maths and engineering of spaceflight. the book includes material on rocket propulsion, orbital and interplanetary manouvres, re-entry, attitude control and instruments. Recommended to all undergrads with an interest in spaceflight.

Spacecraft Systems Engineering
Editors : Peter Fortescue and John Stark
Publisher : Wiley
A good introduction to spacecraft systems. The various authors look at all aspects of spacecraft mission design, and describe the techniques and technology used in the construction of spacecraft. It includes sections on propulsion and launching which would be of interest to anyone learning about rocketry.

Understanding Space
Author : JJ Sellers Publisher : Mc Graw Hill I have yet to find a better textbook for introducing all the issues of spaceflight under one cover. The breadth of this book is amazing, and the clarity of its diagrams and explanations is second to none. It presents complex material in a manner analogous to a secondary school textbook, helping readers to understand the science and engineering of spaceflight. Worked examples, clear diagrams and chapter summaries gradually reveal the world of spaceflight in all its glorious complexity. This book is a masterpiece.

Fundamantals of Astrodynamics
Author : RR Bate, DD Mueller, JE White
Publisher : Dover A surprisingly inexpensive introduction to the trajectories of spaceflight. It comprehensively covers, in a mathematical form, the basic problems of spaceflight dynamics. Material covered includes orbital manouvres, intercept problems, the patched conic appromation for interplanetray flight, and the general form of the ballistic missile equation. This is hard core space science on a low budget.

Topics in Advanced Model Rocketry
Author : GK Mandell, GJ Caporaso, WP Bengen
Publisher : MIT Press
This book should be read by all HPR fliers. It is equal in significance to "Stine", to whom it is dedicated. It is a bound volume of four papers which establish the engineering principles and mathematics of HPR. The papers are supported by experimental results including wind tunnels tests. The four papers cover dynamics of flight, aerodynamic stability, aerodynamic drag and trajectory analysis. After reading this the reader will completely understand the origins of the rules of thumb and folklore of rocketry, and will be equipped with the basic science and maths to start the path to real rocket science.

Authors : R Wolfson, JM Pasachoff
Publisher : Addison Wesley
There are many good intermediate level physics textbooks on the market but I found this one to be both affordable and clear. The diagrams and layout make it very easy to understand, yet it avoids over simplification. The book has several nice touches including its use of real-world examples, and the "tips" boxes to help readers to avoid common pitfalls.

Aerodynamics for Engineering Students
Authors: E L Houghton, A E Brock:
Publisher : Arnold
First published in 1960, this book is aimed at first and second year engineering undergraduates. It is very much written around subsonic flight of airccraft, so it would not appear to be relevant to rockets. Its strength is that it gives a solid theoretical and practical grounding in aerodynamics and is a good starting point for anyone wishing to study the subject.

Engineering Mathematics & Further Engineering Mathematics
Author: K A Stroud
Publisher: Macmillan
Everything you wanted to know about undergraduate engineering mathematics and were afraid to ask. This is a first rate pair of books which take you gently from A level maths to about the end of the second year of an engineering degree. The books are rich in examples and lead you gently through each subject, building your confidence. These books have been my reference since the mid 1970s. I doubt that a better pair of maths books will ever be written.

Satellite Communications
Authors: G Maral, M Bousquet
Publisher: Wiley
A classic book on all aspects of satellite communications and probably the most thumbed book in my library. I had to buy a copy of thr fourth edition as the third edition fell to pieces from use! If you're serious about understanding satellites then this is the book to start you off. It covers orbits, payloads, link budgets, launching, multiple access and all the basic issues at an introductory level. It's a bit "mathy" in places as maths is the language of engineering.

Fundamentals of Astrodynamics and Applications
Dave Vallado
A great introduction to Astrodynamics. This book is not only a good text book but also a good reference book. It starts with a short history of the subject from ancient times. After establishing some basic principles, common to all books on this subject, the author introduces new ideas in logical order until the reader has a very comprehensive view of the subject. The author uses a fair amount of maths, inevitable given the subject, but explains it clearly. This is one of my favourite books, and is seldom far away from my desk. It's expensive, but an essential text for anyone who's seriously interested in astrodynamics.