Experimental Performance Evaluation of Coaxial Rotors for a Micro Aerial Vehicle
01 Oct 2013-Journal of Aircraft (American Institute of Aeronautics and Astronautics)-Vol. 50, Iss: 5, pp 1465-1480
TL;DR: In this paper, an experimental study performed on a coaxial-contrarotor helicopter model was performed to evaluate the performance of the rotor system using different rotor blades. But, the results of the experimental study were limited to a single-rotor configuration and the percentage thrust loss in the coaxial configuration was seen to be dependent on the ratio of the upper and lower rotor revolutions per minute as well as the spacing between the rotors.
Abstract: Because of their potential for application in both civil and military sectors as well as the challenge in designing a tiny flying vehicle, micro aerial vehicles have attracted enormous attention. Several configurations of micro aerial vehicles are under development, namely fixed wing, rotary wing, and flapping wing. Under rotary-wing micro aerial vehicles, coaxial contrarotating configurations with a stabilizer bar seem to provide excellent stability behavior in pitch and roll degrees of freedom. This paper presents the results of an experimental study performed on a coaxial-contrarotor helicopter model to evaluate the performance of the rotor system using different rotor blades. The thrust and power of the rotors in independent and coaxial configurations were observed. The percentage thrust loss in the coaxial configuration was seen to be dependent on the ratio of the upper- and lower-rotor revolutions per minute as well as the spacing between the rotors. A theoretical analysis using a nonuniform inflow ...
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05 Jan 2015
TL;DR: A complete dynamic model for an unmanned coaxial helicopter is established which is proven accurate but simple enough for dynamic analysis and real time simulation.
Abstract: Modeling and analysis of a coaxial helicopter’s dynamics is a demanding work because of the complex characteristics in rotor aerodynamics and swashplate mechanism. In this paper, a complete dynamic model for an unmanned coaxial helicopter is established which is proven accurate but simple enough for dynamic analysis and real time simulation. An 14-states aerodynamic model including flapping dynamics and induced velocities is derived considering interaction between rotors. The model is validated to have a good consistency with existed experimental and CFD results. After that, by introducing swashplate kinematics, actuator dynamics and rigid body dynamics, a complete model is constructed. Trim analysis is performed over a large range of forward flight speed, and the hovering performance is analyzed by calculating the necessary power and rotors’ figure of merit in different altitude and load. The coupling between heave and yaw motion is also analyzed to propose a decoupling strategy in control design.
8 citations
TL;DR: Simulation and experiment compared with the conventional PIDC are carried out, the results demonstrate the effectiveness and the robustness of the proposed control method of this paper.
7 citations
TL;DR: In this article , a combinatorial control method of sliding mode control (SMC) coupled with proportional-integral-derivative control (PIDC) is proposed for position and attitude tracking of coaxial rotor aircraft (CRA).
5 citations
TL;DR: In this article , a ducted fan UAV is designed using the open source code OpenProp and the computational fluid dynamics simulation model using sliding mesh technique is established and validated as a reliable tool for highly vortical flows by propeller thrust experiment.
Abstract: Recently, ducted fan unmanned aerial vehicles (UAVs) have attracted considerable attention due to their potential for application in both civil and military missions. Compared with free propellers, the presence of duct can in principle decrease the flow contraction after propeller, and gives the potential to fly efficiently with high security, compact structure, and low noise. In the present study, a ducted fan UAV is designed using the open source code OpenProp. The computational fluid dynamics (CFD) simulation model using sliding mesh technique is established and validated as a reliable tool for highly vortical flows by propeller thrust experiment. The effect of the duct, revolution speed, and distance between propellers on the aerodynamic characteristics of the ducted fan UAV is evaluated in detail. Results show that the unducted coaxial upper and lower propellers generate 3.8%, 4.3% more thrust than the unducted single propellers, respectively, and the unducted upper and lower propellers generate 55.9%, 34.9% more thrust than ducted propellers, respectively. The ducted fan UAV generates 5.7% more thrust and consumes 39.1% less power than the unducted coaxial propellers. The thrust of the ducted fan UAV increases first and then follows with a decreased tendency as the distance between propellers increases.
3 citations
TL;DR: In this paper , a consideration of the coaxial rotor Mini UAV to analyse the suitability for mountain terrain is presented, and various design parameters are analyzed to arrive at viable design configurations for coaxial rotary wing UAVs to operate in mountain terrain.
Abstract: Due to its compactness, agility, good hover performance, and ease of carriage, coaxial rotor Mini UAV is apt for various military and civilian applications in mountain terrain. This paper examines various factors to arrive at viable configurations of coaxial rotor Mini UAV for applications in mountain terrain. A consideration of the coaxial rotor Mini UAV to analyse the suitability for mountain terrain is presented. Coaxial rotor design is evaluated to assess the design requirements of mountain terrain. Various design parameters are analysed to arrive at viable design configurations for coaxial rotor Mini UAVs to operate in mountain terrain. Due to mechanical complexities, more than three blades per rotor for a small coaxial rotary wing aircraft is not recommended. The compact frame of the coaxial rotor Mini UAV is a key advantage, so rotor blades with a radius bigger than 1 m are not desirable. With a radius smaller than 1 m, a range of 0.9 m to 1.2 m, and an rotor speed between 900 RPM and 1200 RPM for 3-blade and 2-blade coaxial rotors, the Mini UAV offers a variety of options for applications in mountain terrain.
1 citations
References
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Book•
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.
2,146 citations
05 Feb 2001
TL;DR: In this article, a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems is presented.
Abstract: Low-speed aerodynamics is important in the design and operation of aircraft flying at low Mach number, and ground and marine vehicles. This 2001 book offers a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems. A unique feature of the text is that the computational approach (from a single vortex element to a three-dimensional panel formulation) is interwoven throughout. Thus, the reader can learn about classical methods of the past, while also learning how to use numerical methods to solve real-world aerodynamic problems. This second edition has a new chapter on the laminar boundary layer (emphasis on the viscous-inviscid coupling), the latest versions of computational techniques, and additional coverage of interaction problems. It includes a systematic treatment of two-dimensional panel methods and a detailed presentation of computational techniques for three-dimensional and unsteady flows. With extensive illustrations and examples, this book will be useful for senior and beginning graduate-level courses, as well as a helpful reference tool for practising engineers.
1,810 citations
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01 Jan 1926
TL;DR: The aerofoil in three dimensions has been studied in this article, where Bernoulli's equation and the potential function are used to transform a circle into an acerofoil.
Abstract: 1. Introduction 2. Bernoulli's equation 3. The stream function 4. Circulation and vorticity 5. The velocity potential and the potential function 6. The transformation of a circle into an aerofoil 7. The aerofoil in two dimensions 8. Viscosity and drag 9. The basis of aerofoil theory 10. The aerofoil in three dimensions 11. The monoplane aerofoil 12. The flow round an acerofoil 13. Biplane aerofoils 14. Wind tunnel interference on areofoils 15. The airscrew: momentum theory 16. The airscrew: blade element theory 17. The airscrew: wind tunnel interference Appendix Bibliography Index.
668 citations
01 Mar 1997
TL;DR: In this paper, the aerodynamic issues peculiar to coaxial rotors were surveyed by surveying American, Russian, Japanese, British, and German research, including the effects of having no tail rotor.
Abstract: The recent appearance of the Kamov Ka-50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in the coaxial rotor configuration. This report addresses the aerodynamic issues peculiar to coaxial rotors by surveying American, Russian, Japanese, British, and German research. (Herein, 'coaxial rotors' refers to helicopter, not propeller, rotors. The intermeshing rotor system was not investigated.) Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. A general summary of the coaxial rotor configuration explores the configuration's advantages and applications.
167 citations
TL;DR: In this paper, the aerodynamic characteristics of airfoils operating at Re = 4 X 10 3 were examined, varying the parameters related to the airfoil shape such as thickness, camber, and roughness.
Abstract: The aerodynamic characteristics of airfoils operating at Re = 4 X 10 3 were examined, varying the parameters related to the airfoil shape such as thickness, camber, and roughness. Airfoils with good aerodynamic performance at this Re have the following shape characteristics : (1) they are thinner than airfoils for higher Re numbers, (2) they have a sharp leading edge, and (3) they have a camber of about five percent with its maximum camber at about mid-chord. The characteristics of airfoils are strongly affected by leading edge vortices. The measured two-dimensional airfoil characteristics indicate that the planform, which greatly affects the flight performance of the three-dimensional wing at high Reynolds numbers, has little effect on the flight performance at this Reynolds number.
157 citations