This book was written for young aviation enthusiasts and is especially meant as a "guide" for students of technical universities and high schools but also for young engineers involved in both designing and building light aeroplanes. The five parts this book is composed of are as follows: Part 1: Reference documents and book content Part 2: The historical development of light aircraft in Europe and the USA, with the purpose of being an aircraft for transportation and leisure. This part is useful to understand future trends. Part 3: The introductory and preliminary explanation of the matter that will be dealt with and developed in the fourth and fifth parts. Part 3 has been written so that we can gain a better understanding of the meaning of the calculations on the light aircraft example shown in the two following parts. Part 4: The steps needed to prepare calculations based on the sample aircraft that will be presented to the certifying authority Part 5: Structural calculations and assumed weight validation