Helicopter Performance, Stability, and Control

The purpose of this book is to provide both the student and the practicing helicopter aerodynamicist with the information they need to analyze the performance of an existing helicopter or to participate in the design of a new helicopter. This text should also be helpful for those in the helicopter industry who work with aerodynamicists and may have been baffled by what seemed to be an art rather than a science. The information presented here includes the derivation of the theory behind the various methods of analysis, appropriate experimental data to correlate and supplement the theory, and charts that permit rapid analysis. A special attempt is made to relate helicopter aerodynamics to airplane aerodynamics for those who are making the transition.

To focus on the practical aspects of the subject, an "Example Helicopter” is defined in Appendix A and is consistently used throughout the book to illustrate, by numerical calculations, the application of the analysis. These calculations are listed at the end of each chapter, along with a listing of "How To’s,” which can be used to shorten the search for a specific subject. Although no problems are presented at the ends of chapters, they can easily be generated using the example helicopter calculations as examples and the helicopter parameters selected by the instructor or the student. The generation of problems involving extension of the theory, wherein the proof is left to the ambitious student, is left to the ambitious instructor.

The first six chapters are devoted to tfye various aspects of helicopter performance. Chapters 7, 8, and 9 cover stability and control. The final chapter presents the tradeoff considerations that the engineer must face during the

preliminary design phase to ensure both good performance and good flying qualities.

Aeroelastic rotor effects, including vibration, oscillating loads, and the stability of nonconventional rotors, are not addressed. For an understanding of these mysterious effects, other sources must be consulted.

The material includes almost all of the information and methods that I have found to be significant as a working aerodynamicist for Hughes, Sikorsky, Bell, and Lockheed since 1952. The outline of the book was first developed as lecture notes used in teaching engineering extension courses at the University of California at Los Angeles.