The object of the present volume is to give an up-to-date account of the more important branches of the dynamics and aerodynamics of the helicopter. It is hoped that it will be useful to both undergraduate and postgraduate students of aeronautics and also to workers in industry and the research establishments. In these days of fast computers it is a temptation to consign a problem to arithmetical computer calculation straightaway. While this is unavoidable in many complicated problems, such as the calculation of induced velocity, the important physical understanding is thereby often lost. Fortunately, most problems of the helicopter can be discussed adequately without becoming too involved mathematically, and it is usually possible to arrive at relatively simple formulae which are not only useful in preliminary design but which also enable a physical interpretation of the dynamic and aerodynamic phenomena to be obtained. The intention throughout this book, therefore, has been to try to arrive at useful mathematical results and ‘working formulae’ and at the same time to emphasize the physical understanding of the problem.

Contents

Preface to the second edition vii Preface to the first edition ix Acknowledgements xi Notation xiii 1. Basic mechanics of rotor systems and helicopter flight 1 2. Rotor aerodynamics in axial flight 33 3. Rotor aerodynamics and dynamics in forward flight 77 4. Trim and performance in axial and forward flight 115 5. Flight dynamics and control 137 6. Rotor aerodynamics in forward flight 196 7. Structural dynamics of elastic blades 238 8. Rotor induced vibration 290 9. Aeroelastic and aeromechanical behaviour 319

Bramwell, A.R.S.

Bramwell’s helicopter dynamics. – 2nd ed.

1 Helicopters – Aerodynamics