A Review of Fundamentals of Sailplane Design by Fred Thomas and Judah Milgram
Fundamentals of Sailplane Design is a book that covers the theory and practice of designing high-performance sailplanes. It was written by Fred Thomas, a professor of aerodynamics at the Technical University of Braunschweig and a former director of the DLR Braunschweig Research Center, and translated and edited by Judah Milgram, a naval architect and engineer. The book was first published in German in 1989 and has been revised and updated several times. The latest English edition was published in 1999 by College Park Press.
The book is divided into five parts: aerodynamics, flight mechanics, certification regulations, cross-country theory, and design optimization. It explains the physical principles and mathematical methods that govern the performance and behavior of sailplanes, as well as the practical aspects of designing, testing, and certifying them. The book also includes a reference section with basic design data for over 150 sailplanes from different countries and eras.
The book is intended for students, pilots, engineers, and enthusiasts who are interested in learning more about the science and art of sailplane design. It assumes some basic knowledge of physics and mathematics, but does not require advanced expertise. The book emphasizes physical relationships rather than mathematical detail, making it suitable for beginners and experts alike. The book also contains many illustrations, diagrams, tables, graphs, and examples to help the reader understand the concepts and applications.
Fundamentals of Sailplane Design is a unique and valuable resource for anyone who wants to learn more about the fascinating field of sailplane design. It combines theoretical rigor with practical relevance, and offers a comprehensive overview of the state-of-the-art in sailplane technology. It is a must-read for anyone who loves soaring.
One of the ways to improve the performance of sailplanes is to use winglets, which are vertical extensions of the wingtips that reduce the induced drag and increase the span efficiency. Winglets can also improve the handling qualities and stability of sailplanes by providing additional yaw damping and roll control. However, designing winglets for sailplanes is not a trivial task, as it involves a trade-off between various objectives and constraints. For example, winglets can increase the root bending moment and the structural weight of the wing, which can affect the safety and maneuverability of the sailplane. Winglets can also affect the cruise drag and the cross-country speed of the sailplane, depending on the flight conditions and the wing loading.
A multi-objective optimization process can be used to design winglets for sailplanes that maximize the performance benefits while minimizing the drawbacks. This process involves defining a set of cost functions that represent the objectives and constraints of the design problem, such as average cross-country speed, cruise drag, root bending moment, etc. The cost functions are then evaluated using a numerical method that simulates the aerodynamics and flight mechanics of the sailplane with and without winglets. The optimal winglet designs are then selected from a set of Pareto-optimal solutions that represent the best trade-offs among the cost functions.
An example of using an optimization process for sailplane winglet design is presented by Krebs and Bramesfeld[^1^], who designed winglets for a high-performance sailplane called ASW-27B. They used a higher-order potential flow method to evaluate the aerodynamics of the sailplane with different winglet geometries, and a simple flight performance model to calculate the average cross-country speed over a range of thermal strengths. They also considered the effects of winglet weight, root bending moment, and cruise drag on the design objectives. They compared their optimal winglet designs to a traditionally designed winglet for the same aircraft, and found that their designs provided an increase in average cross-country speed of 1.5% at lower thermal strengths and 0.4% at higher thermal strengths. ec8f644aee