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 Theory Test Correlation of Helicopter Rotor Blade Element Airloads in the Blade Stall Regime written by Christopher J. Bobo and published by . This book was released on 1972 with total page 102 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 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 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 Wind Tunnel Evaluation of a Model Helicopter Main Rotor Blade With Slotted Airfoils at the Tip written by and published by . This book was released on 2001 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Special Opportunities in Helicopter Aerodynamics written by W. J. McCroskey and published by . This book was released on 1983 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic research relating to modern helicopters includes the study of three-dimensional, unsteady, nonlinear flow fields. A selective review is made of some of the phenomenon that hamper the development of satisfactory engineering prediction techniques, but which provides a rich source of research opportunities: flow separations, compressibility effects, complex vortical wakes, and aerodynamic interference between components. Several examples of work in progress are given, including dynamic stall alleviation, the development of computational methods for transonic flow, rotor-wake predictions, and blade-vortex interactions. (Author).
Download or read book The Response and Airloading of Helicopter Rotor Blades Due to Dynamic Stall written by Wayne Robert Johnson and published by . This book was released on 1970 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: An aerodynamic model is constructed for the application of the properties of dynamic stall of airfoils to the calculation of the airloads and blade motion of helicopter rotor blades. Dynamic stall occurs on an airfoil undergoing pitching motion at high angle of attack, and is characterized by peak section lift and moment much larger than the corresponding static stall loads. A method is developed for the solution of the equations of motion of a rotor blade by means of harmonic analysis. The effect of dynamic stall on the blade torsional motion at high advance ratio is examined, and comparison is made with the limited experimental data available. An increase in the dynamic stall angle is shown to significantly decrease the amplitude of the pitch motions. (Author).
Download or read book Correlation of Airloads on a Two bladed Helicopter Rotor written by Francisco J. Fernandez and published by . This book was released on 1993 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Technical Information Indexes written by United States. Naval Air Systems Command and published by . This book was released on 1976 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotating Shake Test and Modal Analysis of a Model Helicopter Rotor Blade written by W. Keats Wilkie and published by . This book was released on 1997 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1989 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Rotor Harmonic Airloads Including the Effects of Rotor rotor Interference and Blade Flexibility written by Norman D. HAM and published by . This book was released on 1965 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental airload harmonics from the first to the tenth at various blade spanwise stations are presented for single and rear tandem rotor configurations for various rotor angles of attack, tip-speed ratios, and thrust loadings. The results include the effect of blade bending motion on airload harmonics for selected test cases. Evaluation of the experimental results indicates several general conclusions of importance with regard to vibration levels of compound helicopters, tandem helicopters, and three- and four-bladed rotors. (Author).
Download or read book An Experimental Study of the Sensitivity of Helicopter Rotor Blade Tracking to Root Pitch Adjustment in Hover written by and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1991 with total page 538 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 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
