Download or read book Experimental Investigation of the Effects of Helicopter Rotor Design Parameters on Forward Flight Stall Characteristics written by Elton Dean Bellinger and published by . This book was released on 1974 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to determine the effects of number of blades, twist, aspect ratio, camber, taper ratio, and torsional frequency on helicopter rotor stall characteristics in forward flight. The tests were conducted in the low-speed UARL 4- x 6-ft wind tunnel with 4.7-ft-diameter model rotors having flapping articulation. Stall conditions were approached by means of increasing rotor shaft angle at fixed collective pitch. Torsional frequency was varied by using a special blade root flexure which would produce the required rigid blade torsional frequencies. Rotor performance, blade response, and boundary layer separation data were acquired to determine the occurrence and extent of blade stall. (Modified author abstract).
Download or read book An Experimental Investigation of Stall Flutter of a Model Helicopter Rotor in Forward Flight written by NORMAN D. HAM and published by . This book was released on 1960 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stalling of Helicopter Blades written by F. B. Gustafson and published by . This book was released on 1946 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical studies have predicted that operation of a helicopter rotor beyond certain combinations of thrust, forward speed, and rotational speed might be prevented by rapidly increasing stalling of the retreating blade. The same studies also indicate that the efficiency of the rotor will increase unitl these limits are reached or closely approached, so that it is desirable to design helicopter rotors for operation close to the limits imposed by blade stalling. Inasmuch as the theoretical predictions of blade stalling involve numerous approximations and assuptions of blade stalling, an experimental investigation was needed to determine whether, in actual practice, the stall did occur and spread as predicted and to establish the amount of stalling that could be present without severe vibration or control difficulties being introduced.
Download or read book Experimental Investigation of Model Variable geometry and Ogee Tip Rotors written by Anton J. Landgrebe and published by . This book was released on 1974 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to systematically explore the effects of inter-blade spatial relationships and pitch variations on rotor performance and wake geometry. Variable-geometry rotors consisting of various combinations of blade length, axial spacing, azimuth spacing, and collective pitch were tested at model scale in hover and forward flight. In addition, a hover test of a model rotor with an ogee blade tip design was conducted to determine its performance and wake characteristics. The results of this investigation indicate that properly selected variable geometry rotor configurations can offer substantial improvements in hover performance without adversely affecting forward flight performance. Axial spacing of alternate blades was found to provide the greatest performance benefit, and further improvements were achieved by combining azimuth spacing with axial spacing. The performance benefit appears to be related to the relief of local adverse aerodynamic phenomena produced by vortex interference. The ogee tip design was found to substantially reduce the concentrated core intensity of the tip vortex, and could thus prove beneficial for the relief of blade-vortex interaction problems. However, the ogee tip was found to reduce hover performance at model scale.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Helicopter Rotor Blade Element Airloads on a Model Rotor in the Blade Stall Regime written by and published by . This book was released on 1971 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of the Effects of Blade Structural Design Parameters on Helicopter Stall Boundaries written by R. H. Blackwell and published by . This book was released on 1974 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and analytical study was conducted to determine the effects of blade structural design parameters on the stall-related operating boundaries of helicopter main rotors. Emphasis was placed on the effects of blade torsional properties on the buildup of vibratory control loads in stall. The analytical methods used in the study were evaluated through correlation with data for two full-scale rotors and data obtained on a two-dimensional airfoil system whose torsional dynamics simulated those of a rotor blade. (Modified author abstract).
Download or read book An Experimental Investigation of the Effect of Wind Tunnel Walls on the Aerodynamic Performance of a Helicopter Rotor written by Victor M. Ganzer 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 Dynamic Stall of Small Wind Systems written by Richard B. Noll and published by . This book was released on 1983 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Effect of Various Parameters Including Tip Mach Number on the Flutter of Some Model Helicopter Rotor Blades written by George W. Brooks and published by . This book was released on 1958 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental studies were made to evaluate some of the effects of parameters such as Mach number, blade angle, and structural damping on the flutter of model helicopter rotor blades in the hovering condition. The model blades had NACA 23012 and 25018 airfoil sections and each was tested at chordwise center-of-gravity locations of approximately 27.5 and 37 percent chord. Data were obtained at test-medium densities ranging from 0.0012 to 0.0050 slug per cubic foot and at various pitch angles up into the stall. Mixtures of air and Freon-12 were used for the test medium in order to extend the tip Mach number range of the tests to slightly above unity.
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1975 with total page 2834 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications Cumulative Index written by United States. Superintendent of Documents and published by . This book was released on 1976 with total page 1408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of a Bearingless Helicopter Rotor Concept Having a Composite Primary Structure written by Richard L. Bielawa and published by . This book was released on 1976 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of the Near Wake Structure of a Helicopter Rotor in Forward Flight written by G. Briassulis and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Flow Through a Helicopter Rotor in Forward Flight written by P. Brotherhood and published by . This book was released on 1949 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements written by and published by . This book was released on 1974 with total page 1048 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Flow Through a Helicopter Rotor in Forward Flight written by Aeronautical Research Council (Great Britain) and published by . This book was released on 1952 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
