Helicopter Dynamics

Abstract

This is an introductory text which should be accessible to beginning graduate students and most seniors in the mechanically based branches of engineering. While the reviewer would prefer, especially for an introduction, a more pedantic style which clearly delineates between primitives, definitions, axioms, theorems, and proofs, the conversational tone adopted here has proven to be more generally palatable to both students and teachers; and it is predicted that An Introduction to Therrnomechanics will enjoy the same wide acceptance as Professor Ziegler's other books. The first three chapters, on mathematics, kinematics, and kinetics, are based on Prager's Introduction to Mechanics of Continua. The next two chapters are concerned with thermodynamics and material properties. Chapters 6-11 are brief treatments of ideal liquids, linear elasticity, inviscid gases, viscous fluids, plasticity, and viscoelasticity. Chapters 12 and 13, on general tensors and large displacements, are fashioned after Theoretical Elasticity by Green and Zerna. Chapters 14 and 15 are devoted to a presentation of Ziegler's own notion of thermodynamic orthogonality and its immediate consequences. Finally, the last three chapters provide second looks at non-Newtonian fluids, plasticity, and viscoelasticity in light of the orthogonality principle. Of course, the thermodynamical aspects of therrnomechanics are still fraught with controversy, and there are even strong opinions on how best to develop the generally accepted mechanical aspects of the subject. The author has wisely chosen to present his views directly without criticism of or comparison to other approaches. However, the reviewer did notice several slips which transcend the realms of controversy and taste. In the development of stress, Cauchy's lemma (Newton's third law of action and reaction) is tacitly assumed. In the 'development of heat conduction, it is directly assumed that the heat flow per unit area is the inner product of the heat flux vector and the surface normal. This is analogous to starting with the stress tensor and then assuming that it operates on the normal to produce the stress vector. The concept of material frame-indifference does not appear at all in the book. Finally, both the printing and binding of the review copy were poorly done.

Influence of Forward and Descent Flight on Quadrotor Dynamics

“…Figure 5 shows this infinitesimal part of quadrotor's blade together with elemental lift and drag forces it produces Bramwell et al (2001). For better clarity angles are drawn larger than they actually are:…”

“…On the other hand, blade elemental theory is used to calculate forces and torques acting on the rotor by studying a small rotor blade element modeled as an airplane wing so that the airfoil theory can be applied. Bramwell et al (2001) A combination of these two views, macroscopic and microscopic, yields a base ground for a good approximative mathematical model.…”

“…The proposed analysis of propulsion system is based on the thin airfoil (blade element) theory combined with the momentum theory Bramwell et al (2001). The analysis takes into account the important aerodynamic effects, specific to quadrotor construction.…”

A constrained generalised- $$\alpha $$ α method for coupling rigid parallel chain kinematics and elastic bodies

“…They outline the utility of various methods: 1D + 2D solvers for quick, accurate results; shell methods for flexible beams and bearingless rotors; and 3D solid models to capture realistic beam effects. One of the other distinguishing features of this paper is that it suggests the importance of the control chain on the overall motion of the helicopter blades-something commonly overlooked in typical treaties on helicopter rotor dynamics [12,18,19,36], to list a few.…”

Flap motion of helicopter rotors with novel, dynamic stall model

“…tion (flap movement) [2]. The primary focus of this paper is the flap motion of the rigid blade; specifically, the focus is on an equation that effectively reflects flap movement.…”