Evaluation Of Airfoil Dynamic Stall Characteristics For Maneuverability
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Evaluation Of Airfoil Dynamic Stall Characteristics For Maneuverability
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Author :
language : en
Publisher:
Release Date : 2000
Evaluation Of Airfoil Dynamic Stall Characteristics For Maneuverability written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to many parameters that influence rotors in flight. For single-element airfoils it appears that there is little that can be done to improve rotorcraft maneuverability except to provide good static clmax characteristics and the chord or blade number that is required to provide the necessary rotor thrust. The loading on a helicopter blade during a severe maneuver is examined and it is shown that the blade's dynamic stall function is similar to that obtained in two-dimensional wind tunnel testing. An evaluation of three-dimensional effects for flight and an oscillating wing in a wind tunnel suggests that the two problems are not proper analogues. The utility of the dynamic stall function is demonstrated by evaluating sample theoretical predictions based on semi-empirical stall models and CFD computations. The approach is also shown to be useful in evaluating multi-element airfoil data obtained from dynamic stall tests.
Airfoil Dynamic Stall And Rotorcraft Maneuverability
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Author :
language : en
Publisher:
Release Date : 2000
Airfoil Dynamic Stall And Rotorcraft Maneuverability written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to effects such as the airfoil section profile and Mach number, and appears to be independent of such parameters as Reynolds number, reduced frequency, and blade sweep. For single-element airfoils there is little that can be done to improve rotorcraft maneuverability except to provide good static clmax characteristics and the chord or blade number that is required to provide the necessary rotor thrust. However, multi-element airfoils or airfoils with variable geometry features can provide augmented lift in some cases that exceeds that available from a single-element airfoil. The dynamic stall function is shown to be a useful tool for the evaluation of both measured and calculated dynamic stall characteristics of singleelement, multi-element, and variable geometry airfoils.
Rotorcraft Aeromechanics
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Author : Wayne Johnson
language : en
Publisher: Cambridge University Press
Release Date : 2013-04-29
Rotorcraft Aeromechanics written by Wayne Johnson and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-04-29 with Mathematics categories.
A rotorcraft is a class of aircraft that uses large-diameter rotating wings to accomplish efficient vertical take-off and landing. The class encompasses helicopters of numerous configurations (single main rotor and tail rotor, tandem rotors, coaxial rotors), tilting proprotor aircraft, compound helicopters, and many other innovative configuration concepts. Aeromechanics covers much of what the rotorcraft engineer needs: performance, loads, vibration, stability, flight dynamics, and noise. These topics include many of the key performance attributes and the often-encountered problems in rotorcraft designs. This comprehensive book presents, in depth, what engineers need to know about modelling rotorcraft aeromechanics. The focus is on analysis, and calculated results are presented to illustrate analysis characteristics and rotor behaviour. The first third of the book is an introduction to rotorcraft aerodynamics, blade motion, and performance. The remainder of the book covers advanced topics in rotary wing aerodynamics and dynamics.
Journal Of The American Helicopter Society
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Author : American Helicopter Society
language : en
Publisher:
Release Date : 2001
Journal Of The American Helicopter Society written by American Helicopter Society and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Helicopters categories.
Airfoil Dynamic Stall And Rotorcraft Maneuverability
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Author : William G. Bousman
language : en
Publisher: BiblioGov
Release Date : 2013-08
Airfoil Dynamic Stall And Rotorcraft Maneuverability written by William G. Bousman and has been published by BiblioGov this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-08 with categories.
The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to effects such as the airfoil section profile and Mach number, and appears to be independent of such parameters as Reynolds number, reduced frequency, and blade sweep. For single-element airfoils there is little that can be done to improve rotorcraft maneuverability except to provide good static C(l(max)) characteristics and the chord or blade number that is required to provide the necessary rotor thrust. However, multi-element airfoils or airfoils with variable geometry features can provide augmented lift in some cases that exceeds that available from a single-element airfoil. The dynamic stall function is shown to be a useful tool for the evaluation of both measured and calculated dynamic stall characteristics of single element, multi-element, and variable geometry airfoils.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Airfoil Dynamic Stall And Rotorcraft Maneuverability
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-05-29
Airfoil Dynamic Stall And Rotorcraft Maneuverability written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-29 with categories.
The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to effects such as the airfoil section profile and Mach number, and appears to be independent of such parameters as Reynolds number, reduced frequency, and blade sweep. For single-element airfoils there is little that can be done to improve rotorcraft maneuverability except to provide good static C(l(max)) characteristics and the chord or blade number that is required to provide the necessary rotor thrust. However, multi-element airfoils or airfoils with variable geometry features can provide augmented lift in some cases that exceeds that available from a single-element airfoil. The dynamic stall function is shown to be a useful tool for the evaluation of both measured and calculated dynamic stall characteristics of single element, multi-element, and variable geometry airfoils.Bousman, William G.Ames Research CenterAERODYNAMIC STALLING; ROTARY WING AIRCRAFT; MANEUVERABILITY; VORTICES; AIRFOIL PROFILES; THRUST; LEADING EDGES; MACH NUMBER; PITCHING MOMENTS; REYNOLDS NUMBER; DRAG; AERODYNAMIC LOADS
Nasa Scientific And Technical Publications
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Author :
language : en
Publisher:
Release Date : 1987
Nasa Scientific And Technical Publications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Aeronautics categories.
Flugmechanik Der Hubschrauber
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Author : Walter Bittner
language : de
Publisher: Springer Science & Business Media
Release Date : 2009-03-03
Flugmechanik Der Hubschrauber written by Walter Bittner and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-03-03 with Science categories.
Als integrierter Bestandteil des Transport- und Luftfahrtsystems ist der Hubschrauber heute weder im zivilen noch im militärischen Bereich zu entbehren. Die Flugmechanik, die seinen flugtechnischen Eigenschaften zugrunde liegt, beschreibt der Autor in diesem Buch ausführlich. Seine praktischen Erfahrungen aus der Entwicklung und Herstellung von Hubschraubern stellt er Ingenieuren und all denjenigen zur Verfügung, die mit der Beschaffung und Nutzung von Hubschraubern befasst sind. Die 3. Auflage wurde aktualisiert und verbessert.
Wind Tunnel Evaluation Of A Model Helicopter Main Rotor Blade With Slotted Airfoils At The Tip
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Author :
language : en
Publisher:
Release Date : 2001
Wind Tunnel Evaluation Of A Model Helicopter Main Rotor Blade With Slotted Airfoils At The Tip written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and loads. Four rotor configurations were tested in forward flight at advance ratios from 0.15 to 0.45 and in hover in-ground effect. The hover tip Mach number was 0.627, which is representative of a design point of 4000-ft geometric altitude and a temperature of 95 degrees F. The baseline rotor configuration had a conventional single element airfoil in the tip region. A second rotor configuration had a forward-slotted airfoil with a -6 degrees slat, a third configuration had a forward-slotted airfoil with a -10 degrees slat, and a fourth configuration had an aft-slotted airfoil with a 3 degrees flap (trailing edge down). The results of this investigation indicate that the -6 degrees slat configuration offers some performance and loads benefits over the other three configurations.