Tables of Aerodynamic Derivatives of Oscillating Rotor Blades in Hovering Flight


Book Description

A theory was developed for determining the influence of compressibility on the aerodynamic forces acting on helicopter rotor blades when oscillating in hovering flight. In this theory, the usual two-dimensional mathematical model of the flow was adopted in which a section of the reference rotor balde and its helical wake are replaced by an airfoil with a straight wake and a system of regularly spaced infinite wakes below, the amount of spacing depending on the downward flow induced by the rotor and the number of blades. In this report, the same theory is used to compute the aerodynamic derivative coefficients referred to the quarter-chord point on the airfoil. The results obtained are tabulated for single and two-bladed rotors for a range of values of the parameters involved. (Author).




Research in Progress


Book Description







Experimental Aerodynamic Derivatives of a Sinusoidally Oscillating Airfoil in Two-dimensional Flow


Book Description

Experimental measurements of the aerodynamic reactions on a symmetrical airfoil oscillating harmonically in a two-dimensional flow are presented and analyzed in this paper. Harmonic motions include pure pitch and pure translation, for several amplitudes and superimposed on an initial angle of attack, as well as combined pitch and translation. Considerable consistent data for pure pitch were obtained from a search of available reference material, and several definite Reynolds number effects are evident.










Helicopter Theory


Book Description

Monumental engineering text covers vertical flight, forward flight, performance, mathematics of rotating systems, rotary wing dynamics and aerodynamics, aeroelasticity, stability and control, stall, noise, and more. 189 illustrations. 1980 edition.







Helicopter Flight Dynamics


Book Description

The Book The behaviour of helicopters and tiltrotor aircraft is so complex that understanding the physical mechanisms at work in trim, stability and response, and thus the prediction of Flying Qualities, requires a framework of analytical and numerical modelling and simulation. Good Flying Qualities are vital for ensuring that mission performance is achievable with safety and, in the first and second editions of Helicopter Flight Dynamics, a comprehensive treatment of design criteria was presented, relating to both normal and degraded Flying Qualities. Fully embracing the consequences of Degraded Flying Qualities during the design phase will contribute positively to safety. In this third edition, two new Chapters are included. Chapter 9 takes the reader on a journey from the origins of the story of Flying Qualities, tracing key contributions to the developing maturity and to the current position. Chapter 10 provides a comprehensive treatment of the Flight Dynamics of tiltrotor aircraft; informed by research activities and the limited data on operational aircraft. Many of the unique behavioural characteristics of tiltrotors are revealed for the first time in this book. The accurate prediction and assessment of Flying Qualities draws on the modelling and simulation discipline on the one hand and testing practice on the other. Checking predictions in flight requires clearly defined mission tasks, derived from realistic performance requirements. High fidelity simulations also form the basis for the design of stability and control augmentation systems, essential for conferring Level 1 Flying Qualities. The integrated description of flight dynamic modelling, simulation and flying qualities of rotorcraft forms the subject of this book, which will be of interest to engineers practising and honing their skills in research laboratories, academia and manufacturing industries, test pilots and flight test engineers, and as a reference for graduate and postgraduate students in aerospace engineering.