This book presents general design methods of manned and unmanned aircraft for various types and purposes, as well as the problems of designing their structural and functional elements, based on the principles of a systematic approach and the achievements of modern information technologies. It reflects modern achievements in aircraft engineering, theory and methods of designing aircraft of various types, including aerospace, unmanned aerial vehicles and seaplane aircraft. The first part details the general theory, and the second part covers the engineering of components. This textbook will be used for students enrolled in undergraduate and graduate programs, and can also be useful to engineers and scientists dealing with aircraft design problems, as well as anyone who wants to independently study modern methods of aircraft design.