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Principles of Helicopter Aerodynamics
05 Jun 2000-
TL;DR: A history of helicopter flight can be found in this paper, where the basic helicopter aerodynamic properties are discussed and a detailed analysis of the rotor blade motion is presented, as well as a detailed discussion of the rotor wakes and tip vortices.
Abstract: Preface Acknowledgements List of main symbols List of figures List of tables 1. Introduction: a history of helicopter flight 2. Fundamentals of rotor aerodynamics 3. Blade element analysis 4. Rotating blade motion 5. Basic helicopter performance 6. Conceptual design of helicopters 7. Rotor airfoil aerodynamics 8. Unsteady aerodynamics 9. Dynamic stall 10. Rotor wakes and tip vortices Appendix Index.
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20 Aug 2007
TL;DR: In this paper, a theoretical development is presented, and validated through both thrust test stand measurements and vehicle flight tests using the Stanford Testbed of Autonomous Rotorcraft for Multi-Agent Control (STARMAC) quadrotor helicopter.
Abstract: Quadrotor helicopters are emerging as a popular platform for unmanned aerial vehicle (UAV) research, due to the simplicity of their construction and maintenance, their ability to hover, and their vertical take o and landing (VTOL) capability. Current designs have often considered only nominal operating conditions for vehicle control design. This work seeks to address issues that arise when deviating significantly from the hover flight regime. Aided by well established research for helicopter flight control, three separate aerodynamic eects are investigated as they pertain to quadrotor flight, due to vehicular velocity, angle of attack, and airframe design. They cause moments that aect attitude control, and thrust variation that aects altitude control. Where possible, a theoretical development is first presented, and is then validated through both thrust test stand measurements and vehicle flight tests using the Stanford Testbed of Autonomous Rotorcraft for Multi-Agent Control (STARMAC) quadrotor helicopter. The results enabled improved controller performance.
1,074 citations
TL;DR: In this paper, the authors classify the shape morphing parameters that can be affected by planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness).
Abstract: Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is the short form for metamorphose; however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title ‘shape morphing.’ Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness). Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity, or weight, although in certain circumstances, thes...
1,068 citations
10 Dec 2007
TL;DR: This paper summarizes the final results of the modeling and control parts of OS4 project, which focused on design and control of a quadrotor and introduces a simulation model which takes into account the variation of the aerodynamical coefficients due to vehicle motion.
Abstract: The research on autonomous miniature flying robots has intensified considerably thanks to the recent growth of civil and military interest in unmanned aerial vehicles (UAV). This paper summarizes the final results of the modeling and control parts of OS4 project, which focused on design and control of a quadrotor. It introduces a simulation model which takes into account the variation of the aerodynamical coefficients due to vehicle motion. The control parameters found with this model are successfully used on the helicopter without re-tuning. The last part of this paper describes the control approach (integral backstepping) and the scheme we propose for full control of quadrotors (attitude, altitude and position). Finally, the results of autonomous take-off, hover, landing and collision avoidance are presented.
771 citations
Cites background from "Principles of Helicopter Aerodynami..."
...The number of projects tackling this problem has considerably and suddenly increased....
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TL;DR: These apprenticeship learning algorithms have enabled us to significantly extend the state of the art in autonomous helicopter aerobatics, including the first autonomous execution of a wide range of maneuvers, including in-place flips, in- place rolls, loops and hurricanes.
Abstract: Autonomous helicopter flight is widely regarded to be a highly challenging control problem. Despite this fact, human experts can reliably fly helicopters through a wide range of maneuvers, including aerobatic maneuvers at the edge of the helicopterâs capabilities. We present apprenticeship learning algorithms, which leverage expert demonstrations to efficiently learn good controllers for tasks being demonstrated by an expert. These apprenticeship learning algorithms have enabled us to significantly extend the state of the art in autonomous helicopter aerobatics. Our experimental results include the first autonomous execution of a wide range of maneuvers, including but not limited to in-place flips, in-place rolls, loops and hurricanes, and even auto-rotation landings, chaos and tic-tocs, which only exceptional human pilots can perform. Our results also include complete airshows, which require autonomous transitions between many of these maneuvers. Our controllers perform as well as, and often even better than, our expert pilot.
630 citations
Cites background from "Principles of Helicopter Aerodynami..."
...Helicopters are widely regarded to be significantly harder to control than fixed-wing aircraft (see, e.g., Leishman (2000) and Seddon (1990)) At the same time, helicopters provide unique capabilities, such as in-place hover and low-speed flight, important for many applications....
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...Helicopter aerodynamics are, to date, somewhat poorly understood, and (unlike most fixed-wing aircraft) no textbook models will accurately predict the dynamics of a helicopter from only its dimensions and specifications (Seddon 1990; Leishman 2000)....
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01 Jan 2005
TL;DR: AeroDyn as discussed by the authors is a set of routines used in conjunction with an aeroelastic simulation code to predict the aerodynamics of horizontal axis wind turbines, including the effect of wind turbine wakes.
Abstract: AeroDyn is a set of routines used in conjunction with an aeroelastic simulation code to predict the aerodynamics of horizontal axis wind turbines. These subroutines provide several different models whose theoretical bases are described in this manual. AeroDyn contains two models for calculating the effect of wind turbine wakes: the blade element momentum theory and the generalized dynamic-wake theory. Blade element momentum theory is the classical standard used by many wind turbine designers and generalized dynamic wake theory is a more recent model useful for modeling skewed and unsteady wake dynamics. When using the blade element momentum theory, various corrections are available for the user, such as incorporating the aerodynamic effects of tip losses, hub losses, and skewed wakes. With the generalized dynamic wake, all of these effects are automatically included. Both of these methods are used to calculate the axial induced velocities from the wake in the rotor plane. The user also has the option of calculating the rotational induced velocity. In addition, AeroDyn contains an important model for dynamic stall based on the semi-empirical Beddoes-Leishman model. This model is particularly important for yawed wind turbines. Another aerodynamic model in AeroDyn is a tower shadow model based on potentialmore » flow around a cylinder and an expanding wake. Finally, AeroDyn has the ability to read several different formats of wind input, including single-point hub-height wind files or multiple-point turbulent winds.« less
625 citations
Cites methods from "Principles of Helicopter Aerodynami..."
...The BEM theory, generally attributed to Betz and Glauert (1935), actually originates from two different theories: blade element theory and momentum theory (see Leishman 2000)....
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