The Ground Effect on Lifting Propellers

The Ground Effect on Lifting Propellers
Title The Ground Effect on Lifting Propellers PDF eBook
Author Albert Betz
Publisher
Pages 544
Release 1937
Genre Ground-cushion phenomenon
ISBN

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In what follows an estimate will be made of the magnitude of the ground effect. For the two cases where the distance a of the propeller from the ground is very small, and very large, respectively, in comparison with the propeller radius r(sub o) the relations may be simply expressed. We consider first the effect of the ground, assuming that the thrust is held constant, as may be done by a suitable change in the propeller speed.

Wakes of Lifting Propellers (rotors) in Ground Effect

Wakes of Lifting Propellers (rotors) in Ground Effect
Title Wakes of Lifting Propellers (rotors) in Ground Effect PDF eBook
Author F. A. DuWaldt
Publisher
Pages 110
Release 1966
Genre Rotors (Helicopters)
ISBN

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The report presents the development of a wake model for a lifting propeller (rotor) in ground effect and the computational procedure used to determine the spacial distribution of wake vorticity and the induced velocity field accompanying that vorticity distribution. Sample calculations for a two-bladed rotor were carried out on an IBM 7044 computer. Locations of wake vortical elements and the associated induced velocities at selected field points are presented for advance ratios of 0, 0.02, 0.05, and 0.10 for an H/R (ratio of rotor height above ground to rotor radius) of 1.0. Also, a few results for a hovering case with H/R = 0.5 are presented. A calculated root-mean-square velocity map is compared with measured hovering data (time averaged) and good agreement is obtained in the outer half of the slipstream. The implications of computed results with respect to the flow field at a horizontal stabilizer or tail rotor are noted as examples of the use of the model. The wake vortex model used for these calculations is a distorted continuous helix emanating from each blade tip. (Author).

Principles of Helicopter Aerodynamics with CD Extra

Principles of Helicopter Aerodynamics with CD Extra
Title Principles of Helicopter Aerodynamics with CD Extra PDF eBook
Author Gordon J. Leishman
Publisher Cambridge University Press
Pages 860
Release 2006-04-24
Genre Science
ISBN 9780521858601

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Written by an internationally recognized teacher and researcher, this book provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft such as tilt rotors and autogiros. The text begins with a unique technical history of helicopter flight, and then covers basic methods of rotor aerodynamic analysis, and related issues associated with the performance of the helicopter and its aerodynamic design. It goes on to cover more advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, and rotor wakes, and rotor-airframe aerodynamic interactions, with final chapters on autogiros and advanced methods of helicopter aerodynamic analysis. Extensively illustrated throughout, each chapter includes a set of homework problems. Advanced undergraduate and graduate students, practising engineers, and researchers will welcome this thoroughly revised and updated text on rotating-wing aerodynamics.

A Selected Listing of NASA Scientific and Technical Reports for ...

A Selected Listing of NASA Scientific and Technical Reports for ...
Title A Selected Listing of NASA Scientific and Technical Reports for ... PDF eBook
Author
Publisher
Pages 664
Release 1949
Genre Aeronautics
ISBN

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Index of NACA Technical Publications

Index of NACA Technical Publications
Title Index of NACA Technical Publications PDF eBook
Author United States. National Advisory Committee for Aeronautics
Publisher
Pages 616
Release 1949
Genre Aeronautics
ISBN

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Performance

Performance
Title Performance PDF eBook
Author Daniel O. Dommasch
Publisher Elsevier
Pages 480
Release 2014-06-05
Genre Technology & Engineering
ISBN 1483222322

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Performance

Effect of Ground And/or Ceiling Planes on Thrust of Rotors in Hover

Effect of Ground And/or Ceiling Planes on Thrust of Rotors in Hover
Title Effect of Ground And/or Ceiling Planes on Thrust of Rotors in Hover PDF eBook
Author
Publisher
Pages 46
Release 1985
Genre
ISBN

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