Página 1 dos resultados de 215 itens digitais encontrados em 0.014 segundos

Integrated Flight Path Planning System and Flight Control System for Unmanned Helicopters

Jan, Shau Shiun; Lin, Yu Hsiang
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 28/07/2011 Português
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This paper focuses on the design of an integrated navigation and guidance system for unmanned helicopters. The integrated navigation system comprises two systems: the Flight Path Planning System (FPPS) and the Flight Control System (FCS). The FPPS finds the shortest flight path by the A-Star (A*) algorithm in an adaptive manner for different flight conditions, and the FPPS can add a forbidden zone to stop the unmanned helicopter from crossing over into dangerous areas. In this paper, the FPPS computation time is reduced by the multi-resolution scheme, and the flight path quality is improved by the path smoothing methods. Meanwhile, the FCS includes the fuzzy inference systems (FISs) based on the fuzzy logic. By using expert knowledge and experience to train the FIS, the controller can operate the unmanned helicopter without dynamic models. The integrated system of the FPPS and the FCS is aimed at providing navigation and guidance to the mission destination and it is implemented by coupling the flight simulation software, X-Plane, and the computing software, MATLAB. Simulations are performed and shown in real time three-dimensional animations. Finally, the integrated system is demonstrated to work successfully in controlling the unmanned helicopter to operate in various terrains of a digital elevation model (DEM).

Pigeons steer like helicopters and generate down- and upstroke lift during low speed turns

Ros, Ivo G.; Bassman, Lori C.; Badger, Marc A.; Pierson, Alyssa N.; Biewener, Andrew A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Turning is crucial for animals, particularly during predator–prey interactions and to avoid obstacles. For flying animals, turning consists of changes in (i) flight trajectory, or path of travel, and (ii) body orientation, or 3D angular position. Changes in flight trajectory can only be achieved by modulating aerodynamic forces relative to gravity. How birds coordinate aerodynamic force production relative to changes in body orientation during turns is key to understanding the control strategies used in avian maneuvering flight. We hypothesized that pigeons produce aerodynamic forces in a uniform direction relative to their bodies, requiring changes in body orientation to redirect those forces to turn. Using detailed 3D kinematics and body mass distributions, we examined net aerodynamic forces and body orientations in slowly flying pigeons (Columba livia) executing level 90° turns. The net aerodynamic force averaged over the downstroke was maintained in a fixed direction relative to the body throughout the turn, even though the body orientation of the birds varied substantially. Early in the turn, changes in body orientation primarily redirected the downstroke aerodynamic force, affecting the bird’s flight trajectory. Subsequently...

Pigeons Steer Like Helicopters and Generate Down- and Upstroke Lift During Low Speed Turns

Ros, Ivo; Bassman, Lori C.; Badger, Marc A.; Pierson, Alyssa N.; Biewener, Andrew Austin
Fonte: Proceedings of the National Academy of Sciences Publicador: Proceedings of the National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.07044%
Turning is crucial for animals, particularly during predator–prey interactions and to avoid obstacles. For flying animals, turning consists of changes in (i) flight trajectory, or path of travel, and (ii) body orientation, or 3D angular position. Changes in flight trajectory can only be achieved by modulating aerodynamic forces relative to gravity. How birds coordinate aerodynamic force production relative to changes in body orientation during turns is key to understanding the control strategies used in avian maneuvering flight. We hypothesized that pigeons produce aerodynamic forces in a uniform direction relative to their bodies, requiring changes in body orientation to redirect those forces to turn. Using detailed 3D kinematics and body mass distributions, we examined net aerodynamic forces and body orientations in slowly flying pigeons (Columba livia) executing level 90° turns. The net aerodynamic force averaged over the downstroke was maintained in a fixed direction relative to the body throughout the turn, even though the body orientation of the birds varied substantially. Early in the turn, changes in body orientation primarily redirected the downstroke aerodynamic force, affecting the bird’s flight trajectory. Subsequently...

Autonomous aerobatic maneuvering of miniature helicopters

Gavrilets, Vladislav, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 86 p.; 4121016 bytes; 4120824 bytes; application/pdf; application/pdf
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In this thesis, I present an experimentally proven control methodology for the autonomous execution of aerobatic maneuvers with small-scale helicopters, and a low-order dynamic model which adequately describes a miniature helicopter in a wide range of flight conditions, including aerobatics. The control laws consist of steady-state trim trajectory controllers, used prior to, and upon exit from the maneuvers; and a maneuver execution logic inspired by human pilot strategies. In order to test the control laws, a miniature helicopter was outfitted with a custom digital avionics system, and a hardware-in-the-loop simulation was developed. The logic was tested with several aerobatic maneuvers and maneuver sequences, which demonstrated smooth maneuver entry, automatic recovery to a steady-state trim trajectory, and robustness of the trim-trajectory control system toward measurement and modeling errors. Based on these results, I further propose a simplified hybrid model for a helicopter under such closed loop control. The model can be utilized in the development of computationally tractable motion-planning algorithms for agile vehicles.; by Vladislav Gavrilets.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics...

CAS, interdiction, and attack helicopters

Groenke, Andrew S.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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Within days of a major failed strike by attack helicopters during Operation Iraqi Freedom (OIF) analysts were questioning the value of such platforms on the modern battlefield. As OIF moved from combat to stability operations, helicopter losses from enemy action actually increased seemingly strengthening the argument of those who see the helicopter as unsuitable to some combat operations. Attack helicopter operations have diverged into two distinct categories, interdiction and close air support (CAS), since their inception. This thesis argues that attack helicopters are most suited to perform CAS while their employment in interdiction is problematic at best. Doctrine, tactics, and threat are studied as they applied in the Soviet-Afghan War, Desert Storm, and OIF in order to examine the issue across a range of time and types of warfare.

Investigation of increased forward flight velocities of helicopters using second harmonic control and reverse velocity rotor concept

Van Riper, Steven G.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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Approved for public release, distribution is unlimited; Described is the behavior of a rotorcraft equipped with Higher Harmonic Stall Control (HHSC) and a Reverse Velocity Rotor (RVR). Current rotorcraft are limited in forward flight speed by retreating blade stall and compressibility effects on the advancing blade. Stall occurs as the blade encounters increasingly severe reverse flow. HHSC enables conventional rotor systems to fly on the forward and aft sections of the rotor disk, greatly reducing reliance on the mixed flow regions defined by the advancing and retreating blades. Employment of the RVR allows lift generation while the rotor is experiencing reverse flow. A similar type of two per revolution (2/rev) input can be tailored to deliver maximum benefit to RVR equipped rotorcraft. Modification of the Joint Army Navy Rotorcraft Analysis and Design (JANRAD) computer program allows 2/rev cyclic input, use of the RVR, and analysis using high fidelity graphical output to examine angle of attack, coefficient of lift, and air load. Computational results show performance gains in conventional helicopters and high speed flight potential for RVR equipped aircraft. The RVR is applied to the Joint Heavy Vertical Lift (JVHL) aircraft conceptual design for preliminary analysis. This conceptual design can be used as an indicator of the performance of a high speed RVR equipped aircraft.

Optimizing HF antenna systems on the Dolphin and Sea Hawk helicopters

Crawford, James B.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado
Português
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Approved for public release; distribution is unlimited.; Making an aircraft available and modifying it to test various antenna systems and configurations is extremely costly. The computer model is an excellent alternative means of analyzing antenna systems for optimum communication system performance. In this study electromagnetic wire grid computer models of two helicopters and eight HF antenna configurations are developed using Interactive Graphics Utility for Automated NEC Analysis (IGUANA). Numerical Electromagnetics Code (NEC) is used to obtain radiation patterns, and the Advanced Prophet program is used to develop the criteria for judging system effectiveness. These computer results compare favorably with test range data, showing great savings of cost. They provide the additional advantage of showing radiation patterns at an elevated angle for sky wave propagation analysis (patterns which cannot be obtained on an antenna test range). Keywords include: Thesis, Antenna modeling; Antennas, HF; and Numerical electromagnetic code (NEC)

Study of the Light Utility Helicopter (LUH) acquisition program as a model for defense acquisition of non-developmental items

Rubinstein, Judith
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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Approved for public release; distribution is unlimited; The UH-72A Light UtilityHelicopter (LUH)was acquired for performance of general support tasks (training, medical evacuation, law enforcement, etc.) in permissive (non-combat) environments, to replace Vietnam-era helicopters, and to free up Black Hawk UH-60 helicopters for combat use. This acquisition program is the Army’s first major acquisition of commercially available helicopters subsequently modified for military use. Although initial testing and use indicated the need for unforeseen modifications to the helicopters, in most respects, this program was successful. The successes included expeditious acquisition and fielding, avoidance of excessive costs, and acquisition of helicopters that incorporated the latest available technology (developed at industry, not at government, expense). Additionally, the helicopters could be, and were, readily tailored for diverse uses. Also, they highly satisfied users’ requirements. Finally, all deliveries were on-time or ahead of schedule. These successes occurred largely because the UH-72A was a non-developmental item with mature technology at the time of acquisition. The time and expense that would otherwise have been needed for development and for ramp-up of production were avoided. Additional factors contributing to the success of the program were clear definition of the requirement...

Optimally scheduling distribution of the MH-60s helicopter and pilots to combat support (HC) squadrons

Culver, Cory L.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xx, 67 p. : ill. ;
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Approved for public release: distribution is unlimited; The U.S. Navy is replacing the H-46 helicopter with the new MH-60S helicopter. The Fleet Introduction Team has developed a spreadsheet-based schedule that distributes new aircraft and MH-60S trained pilots to the active duty Helicopter Combat Support squadrons. This thesis develops an optimal distribution schedule for helicopters and pilots using an integer programming model called OTHCAM (Optimal Transition, HC allocation Model) that minimizes lost flying days. OTHCAM takes into account variable training durations, travel times and tour lengths, as well as manpower and aircraft constraints. The output is a distribution schedule for new MH-60S helicopters and Fleet Replacement Squadron graduates that minimizes lost flying days while meeting manpower and operational requirements. The schedule developed by OTHCAM reduces lost flying days by 26% compared to the Fleet Introduction Team's existing spreadsheet schedule.; PMA 299, NAVAIR NAS Patuxent River, MD; Lieutenant, United States Navy

Allocating flight hours to Army helicopters

Pippin, Bradley W.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xi, 43 p.;28 cm.
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Approved for public release; distribution is unlimited.; Army helicopter battalions, consisting of 24 helicopters valued from $206.4 million (UH-60 Blackhawk battalion) to $432 million (AH-64 Apache battalion), allocate flight hours to helicopters using manual techniques that have caused an unnecessary decrease in battalion deployability. This thesis models the battalion's flight hour allocation problem using optimization; it develops both a mixed integer linear program and a quadratic program. The 2nd Battalion, 4th Aviation Regiment of 4th Mechanized Division currently uses a spreadsheet implementation of the quadratic program developed by the author called QFHAM (Quadratic Flight Hour Allocation Model), that is available to other battalions for use with existing software and computer resources. The mixed integer linear program, called FHAM (Flight Hour Allocation Model) more appropriately models the problem, but requires additional software. This thesis validates the two models using actual flight hour data from a UH-60 battalion under both typical training and contingency scenarios. The models provide a monthly flight hour allocation for the battalion's aircraft that results in a steady-state sequencing of aircraft into phase maintenance...

Exploring a chromakeyed augmented virtual environment for viability as an embedded training system for military helicopters

Lennerton, Mark J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xviii, 177 p. : ill. (some col.)
Português
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Approved for public release, distribution is unlimited; Once the military helicopter pilot deploys aboard a naval vessel he leaves behind all training platforms, short of the actual aircraft, that present enough fidelity for him to maintain the highest levels of readiness. To that end, this thesis takes a preliminary step in creating a trainer that places the pilot in an immersive and familiar environment to exercise myriad piloting tasks as faithfully and as rigorously as in actual flight. The focus of this thesis it to assess the viability of an chromakeyed augmented virtual environment (ChrAVE) trainer embedded into a helicopter for use in maintaining certain perishable skills. Specifically this thesis will address the task of helicopter low-level land navigation. The ChrAVE was developed to substantiate the viability of having embedded trainers in helicopters. The ChrAVE is comprised of commercial off the shelf (COTS) equipment on a transportable cart. In determining whether a system such as the ChrAVE is viable as a laboratory for continued training in virtual environment, the opinion of actual pilots that were tasked with realistic workloads was used. Additionally, empirical data was collected and evaluated according to the subject pool's thresholds for acceptable low-level navigation performance.; Captain...

A case study of the Avenger : Integrated Logistics Support (ILS) of a Non-developmental Item (NDI); NA

Slaughter, Darrell A.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 107 p.;28 cm.
Português
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The Avenger System is a lightweight, highly mobile, and transportable surface-to-air missile, operated by a two man crew for defense against helicopters and fixed wing aircraft at low altitude in day or night operations that take place in clear or limited adverse weather conditions. The Avenger system includes eight ready-to-fire Stinger missiles and a .50 caliber machine gun integrated with sensors and target acquisition devices. Boeing's Avenger was selected in August 1987 as the Non-developmental Item (NDI) candidate to perform the Line-of-Sight-Rear (LOS-R) role of FAADS. This thesis examines the Integrated Logistics Support Plan (ILSP) for Avenger that provided essential information for the successful performance of the Avenger Integrated Logistics Support (FLS) activities early in the life cycle of the system. The ILSP provided support requirements for the acquisition of the Avenger. The ILSP addressed the general ILS planning and management functions performed during the production and fielding phases of the life cycle. This thesis also examines Avenger Integrated Logistics Support concepts as a Non- developmental Item. A significant lesson learned is that in order for logistics support to be effective, it must be included in the acquisition planning process and considered in formulation of the acquisition strategy.; NA; NA; U.S. Army (U.S.A.) author.

Technological innovation roles and implications in Army Aviation Special Operations

Polen, Richard A.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: x, 47 p. ;
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The Global War on Terror and recent shift of focus from conventional warfare to unconventional warfare reflects a need to replace Cold War era helicopters. Case studies including the development of the AH-56 Cheyenne, OH-13 Sioux, and the MH-60 Direct Action Penetrator provide reference points to develop a general premise of the aviation community's ability to capitalize on technological innovations. Examining the process of innovation throughout the history of Army Aviation will provide a framework to apply the concepts of innovation to the present and future operations of Army Aviation Special Operations. The diffusion of innovation theory identifies that 2.5% of the whole represents the true innovators. The size of the 160th Special Operations Aviation Regiment (SOAR), representing approximately 5% of the entire Army aircraft inventory, is analogous with the concept of true innovators. The 160th SOAR is a great option for the integration of an advanced commercial aircraft, meeting the requirement for a specialized aircraft in Special Operations and the advancement of aircraft for the conventional Army.; US Army (USA) author.

An analysis of the integrated mechanical diagnostics health and usage management system on rotor track and balance

Revor, Mark S.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xx, 80 p.
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Approved for public release, distribution is unlimited; This thesis is concerned with the operational benefit of the Integrated Mechanical Diagnostics Health and Usage Management Systems (IMD HUMS) rotor track and balance (RTB) functionality. The questions addressed are whether there is a savings in flight hours expended on functional check flights (FCF's) when compared to present practices, if there will there be a reduction in directed maintenance man-hours (DMMH) spent on maintenance related to the rotor system, and the impact on Operational Availability. Experiments were conducted using a discrete event simulation model of squadron flight operations and organizational level maintenance. The simulation is generic and can be used in the analysis of other helicopters. Input parameters governing the distributions of maintenance action inter-arrival times were estimated from Naval Aviation Logistics Data Analysis (NALDA) databases and squadron experiences on such systems. The analysis suggests that flight hours spent in FCF are dependent upon vibration growth rate, an unknown quantity, and the maintenance policy for rotor smoothing. Directed maintenance man-hours decrease with increasing numbers of IMD HUMS configured aircraft and further gains are achieved with a maintenance policy suited to a continuous monitoring system.; Captain...

Control loads reduction through control system architecture optimization – application to a conventional rotor on compound helicopters

PARIS, Manuel; EGLIN, Paul; MALBURET, François; CARMONA, Jean-Claude
Fonte: AHS Publicador: AHS
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A kinematic study of a helicopter main rotor control system is carried out to investigate loads in servo actuators and non-rotating scissors during high speed and high load factors maneuvers. The kinematic model is then used to optimize the servo-actuators placement and pre-inclination in order to minimize static and dynamic loads in the three servo-actuators and in the non-rotating scissors. The inputs for the model (blade pitch link loads and pilot input to trim the aircraft) are taken from flight tests measurements, current rotor computations being unable to predict blade root torsion moments vs azimuth with enough accuracy. The analysis is based on X3 demonstrator flight tests, which showed high control system loads that used to reduce flight envelope during the first flight test campaign. Flight tests measurements are used to validate the kinematic model used for the optimization. Computations made for X3 case at 220kts showed a reduction of 40% of maximum static load and 45% of maximum dynamic load on servo-actuators compared to the initial placement of the servo actuators. With appropriate servo actuators pre-inclination, dynamic loads in the non-rotating scissors are decreased by 95% at high speed trim flight. This paper shows how it is possible to keep a conventional rotor control system for compound helicopters. The optimization algorithm presented in this paper can be used for conventional helicopters to reduce loads in the control system and then limit command reinjection because of control system flexibility...

Hybrid 3-D Formation Control for Unmanned Helicopters

Karimoddini, A.; Lin, H.; Chen, B. M.; Lee, T. H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/08/2011 Português
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Teams of Unmanned Aerial Vehicles (UAVs) form typical networked cyber-physical systems that involve the interaction of discrete logic and continuous dynamics. This paper presents a hybrid supervisory control framework for the three-dimensional leader follower formation control of unmanned helicopters. The proposed hybrid control framework captures internal interactions between the decision making unit and the path planner continuous dynamics of the system, and hence improves the system's overall reliability. To design such a hybrid controller, a spherical abstraction of the state space is proposed as a new method of abstraction. Utilizing the properties of multi-affine functions over the partitioned space leads to a finite state Discrete Event System (DES) model, which is shown to be bisimilar to the original continuous-variable dynamical system. Then, in the discrete domain, a logic supervisor is modularly designed for the abstracted model. Due to the bisimilarity between the abstracted DES model and the original UAV dynamics, the designed logic supervisor can be implemented as a hybrid controller through an interface layer. This supervisor drives the UAV dynamics to satisfy the design requirements. In other words, the hybrid controller is able to bring the UAVs to the desired formation starting from any initial state inside the control horizon and then...

3-D Reciprocal Collision Avoidance on Physical Quadrotor Helicopters with On-Board Sensing for Relative Positioning

Conroy, Parker; Bareiss, Daman; Beall, Matt; Berg, Jur van den
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/11/2014 Português
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In this paper, we present an implementation of 3-D reciprocal collision avoidance on real quadrotor helicopters where each quadrotor senses the relative position and velocity of other quadrotors using an on-board camera. We show that using our approach, quadrotors are able to successfully avoid pairwise collisions in GPS and motion-capture denied environments, without communication between the quadrotors, and even when human operators deliberately attempt to induce collisions. To our knowledge, this is the first time that reciprocal collision avoidance has been successfully implemented on real robots where each agent independently observes the others using on-board sensors. We theoretically analyze the response of the collision-avoidance algorithm to the violated assumptions by the use of real robots. We quantitatively analyze our experimental results. A particularly striking observation is that at times the quadrotors exhibit "reciprocal dance" behavior, which is also observed when humans move past each other in constrained environments. This seems to be the result of sensing uncertainty, which causes both robots involved to have a different belief about the relative positions and velocities and, as a result, choose the same side on which to pass.; Comment: 8 pages...

Recent European Developments in Helicopters

von Kármán, Th.
Fonte: National Advisory Committee on Aeronautics Publicador: National Advisory Committee on Aeronautics
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em /04/1921 Português
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Descriptions are given of two captured helicopters, one driven by electric power, the other by a gasoline engine. An account is given of flight tests of the gasoline powered vehicle. After 15 successful flight tests, the gasoline powered vehicle crashed due to the insufficient thrust. Also discussed here are the applications of helicopters for military observations, for meteorological work, and for carrying radio antennas.

Of hummingbirds and helicopters: Hovering costs, competitive ability, and foraging strategies

Altshuler, Douglas L.; Stiles, F. Gary; Dudley, Robert
Fonte: Umiversity of Chicago Press Publicador: Umiversity of Chicago Press
Tipo: Article; PeerReviewed Formato: application/pdf; text/plain; text/plain
Publicado em /01/2004 Português
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Wing morphology and flight kinematics profoundly influence foraging costs and the overall behavioral ecology of hummingbirds. By analogy with helicopters, previous energetic studies have applied the momentum theory of aircraft propellers to estimate hovering costs from wing disc loading (WDL), a parameter incorporating wingspan (or length) and body mass. Variation in WDL has been used to elucidate differences either among hummingbird species in nectar-foraging strategies (e.g., territoriality, traplining) and dominance relations or among gender-age categories within species. We first demonstrate that WDL, as typically calculated, is an unreliable predictor of hovering (induced power) costs; predictive power is increased when calculations use wing length instead of wingspan and when actual wing stroke amplitudes are incorporated. We next evaluate the hypotheses that foraging strategy and competitive ability are functions of WDL, using our data in combination with those of published sources. Variation in hummingbird behavior cannot be easily classified using WDL and instead is correlated with a diversity of morphological and physiological traits. Evaluating selection pressures on hummingbird wings will require moving beyond wing and body mass measurements to include the assessment of the aerodynamic forces...

Minimum Power Requirements and Optimal Rotor Design for Conventional, Compound, and Coaxial Helicopters Using Higher Harmonic Control

Giovanetti, Eli Battista
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Tese de Doutorado
Publicado em //2013 Português
Relevância na Pesquisa
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This thesis presents a method for computing the optimal aerodynamic performance of conventional, compound, and coaxial helicopters in trimmed forward flight with a limited set of design variables, including the blade's radial twist and chord distributions and conventional and higher harmonic blade pitch control. The optimal design problem, which is cast as a variational statement, minimizes the sum of the induced and viscous power required to develop a prescribed lift and/or thrust. The variational statement is discretized and solved efficiently using a vortex-lattice technique. We present two variants of the analysis. In the first, the sectional blade aerodynamics are modeled using a linear lift curve and a quadratic drag polar, and flow angles are assumed to be small. The result is a quadratic programming problem that yields a linear set of equations to solve for the unknown optimal design variables. In the second approach, the problem is cast as a constrained nonlinear optimization problem, which is solved using Newton iteration. This approach, which accounts for realistic lift and drag coefficients including the effects of stall and the attendant increase in drag at high angles of attack, is capable of optimizing the blade planform in addition to the radial twist distribution and conventional and higher harmonic blade pitch control. We show that for conventional rotors...