Download or read book Non Steady Velocity Measuremeht of the Wake of a Helicopter Rotor at Low Advanced Ratios written by H. R. Velkoff and published by . This book was released on 1981 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A system was developed which could measure the instantaneous velocities in the wake of a model helicopter rotor operating at low advance ratios. A three-wire hot film probe was mounted on a traverse and placed at many positions in the wake. The output of the probe was fed into an on-line computer operating in an interactive mode. Computer generated vector plots were made of both time averaged velocities and instantaneous velocities for the case of mu = 0.06. (Author).

Download or read book Nonsteady Velocity Measurement of the Wake of a Helicoptor Rotor at Low Advance Ratios written by Hanan Terkel and published by . This book was released on 1980 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Evaluation of a Flat Wake Theory for Predicting Rotor Inflow wake Velocities written by John C. Wilson and published by . This book was released on 1992 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Environment Study Near the Empennage of a 15 Percent Scale Helicopter Model written by Susan Althoff Gorton and published by . This book was released on 2000 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of advanced rotorcraft configurations has highlighted a need for high-quality experimental data to support the development of flexible and accurate analytical design tools. To provide this type of data, a test program was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to measure the flow near the empennage of a 15-percent scale powered helicopter model with an operating tail fan. Three-component velocity profiles were measured with laser velocimetry (LV) one chord forward of the horizontal tail for four advance ratios to evaluate the effect of the rotor wake impingement on the horizontal tail angle of attack. These velocity data indicate the horizontal tail can experience unsteady angle of attack variations of over 30 degress due to the rotor wake influence. The horizontal tail is most affected by the rotor wake above advance ratios of 0.10. Velocity measurements of the flow on the inlet side of the tail fan were made for a low-speed flight condition using conventional LV techniques. The velocity data show an accelerated flow near the tail fan duct, and vorticity calculations track the passage of main rotor wake vortices through the measurement plane.

Download or read book Rotor Flow Research in Low Speed Helicopter Flight written by Henry R. Velkoff and published by . This book was released on 1981 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of helicopter rotor wake flow were made at low advance ratio. Both steady and non-steady data were taken in the wake using 3-D hot-film anemometry. Emphasis was placed on the presentation of the data. Motion pictures were obtained from the computer plots of the experimental velocity data. (Author).

Download or read book Measurements of the Time averaged and Instantaneous Induced Velocities in the Wake of a Helicopter Rotor Hovering at High Tip Speeds written by Harry H. Heyson and published by . This book was released on 1960 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1982 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Environment Study Near the Empennage of a 15 Percent Scale Helicopter Model written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-15 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of advanced rotorcraft configurations has highlighted a need for high-quality experimental data to support the development of flexible and accurate analytical design tools. To provide this type of data, a test program was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to measure the flow near the empennage of a 15-percent scale powered helicopter model with an operating tail fan. Three-component velocity profiles were measured with laser velocimetry (LV) one chord forward of the horizontal tail for four advance ratios to evaluate the effect of the rotor wake impingement on the horizontal tail angle of attack. These velocity data indicate the horizontal tail can experience unsteady angle of attack variations of over 30 degrees due to the rotor wake influence. The horizontal tail is most affected by the rotor wake above advance ratios of 0.10. Velocity measurements of the flow on the inlet side of the tail fan were made for a low-speed flight condition using conventional LV techniques. The velocity data show an accelerated flow near the tail fan duct, and vorticity calculations track the passage of main rotor wake vortices through the measurement plane.Gorton, Susan Althoff and Berry, John D. and Hodges, W. Todd and Reis, Deane G.Langley Research CenterHELICOPTERS; DESIGN ANALYSIS; HORIZONTAL TAIL SURFACES; ROTARY WING AIRCRAFT; SCALE MODELS; ANGLE OF ATTACK; VORTICITY; WAKES; VELOCITY MEASUREMENT; VELOCITY DISTRIBUTION

Download or read book A Full Potential Flow Analysis with Realistic Wake Influence for Helicopter Rotor Airload Prediction written by T. Alan Egolf and published by . This book was released on 1987 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Helicopter Aerodynamics with CD Extra written by Gordon J. Leishman and published by Cambridge University Press. This book was released on 2006-04-24 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Steady and Periodic Pressure Measurements on a Generic Helicopter Fuselage Model in the Presence of a Rotor written by Raymond E. Mineck and published by . This book was released on 2000 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: A wind tunnel test of a generic helicopter fuselage model with an independently mounted rotor has been conducted to obtain steady and periodic pressure data on the helicopter body. The model was tested at four advance ratios and three thrust coefficients. The periodic unsteady pressure coefficients are marked by four peaks associated with the passage of the four rotor blades. Blade passage effects are largest on the nose and tail boom of the model. The magnitude of the pulse increases with rotor thrust coefficient. Tabular listings of the unsteady pressure data are included to permit independent analysis. A CDrom containing the steady and unsteady pressure data presented in the report is available from the authors.

Download or read book Study of Rotor Wakes at Very Low Advance Ratios written by Henry R. Velkoff and published by . This book was released on 1979 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the recognition of the importance of operation of military helicopters at very low altitudes and very low velocities, the need for data on airflow under these conditions became apparent. Work was initiated to obtain data at very low advance ratios typical of such low speed helicopter flight. The original goals of the research were to try to obtain a description of the flow field both time averaged and instantaneous. Because of prior experience with hot wire anemometry the effort was directed towards using a hot wire probe to get all three components of velocity. The effort resulted in an operational rotor drive and measuring system, a probe calibration and positioning system, frequency response determination, and acquisition of average value data. The low speed flow fields found demonstrated a squirting affect that could be seen on both sides of the rotor at very low advance ratios. Two non-steady data acquisition systems were considered, one developed to the point of use but was found awkward to use, and a second interactive system which progressed to the point that initial tests using it in a time average mode illustrated the interactive capability. (Author).

Download or read book Theoretical Prediction of the Flow in the Wake of a Helicopter Rotor written by Peter Crimi and published by . This book was released on 1966 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addendum reports the results of an extension to the study to determine the time varying flow in the vicinity of a helicopter rotor in hovering and forward flight and having a fuselage immersed in the rotor wake. The purpose of the extension was to compare two models representing the fuselage. The first fuselage model (AD-629 782 and AD-629 783), was based upon the assumption that the fuselage was immersed in a constant and uniform flow; the second model was based upon the assumption that the fuselage was immersed in a constant but nonuniform flow. Comparisons between the two models are presented. Program listings and operational information related to the programs are given. (Author).

Download or read book Unsteady Velocity Measurements Taken Behind a Model Helicopter Rotor Hub in Forward Flight written by and published by DIANE Publishing. This book was released on with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1968 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of the American Helicopter Society written by American Helicopter Society and published by . This book was released on 1999 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: