Download or read book Effects of Blade Stall on Helicopter Rotor Blade Bending and Torsional Loads written by S. V. LaForge and published by . This book was released on 1965 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: The highest blade dynamic loads tend to occur under conditions of retreating blade stall. An investigation is made to compare measured and calculated blade bending loads under such conditions. The analysis is based on the use of normal modes and the numerical solution of the differential equations of motion (which eliminates the limitations caused by using harmonics of airloads). It also permits more accurate allowance for aerodynamic nonlinearities in the stalled region. The analysis also includes negative aerodynamic torsional damping when blade stall occurs, as well as the effects of blade bending and torsional deformations on airloads. Finally, the analysis includes an investigation of the effect of hysteresis of the lift coefficient/angle of at8tack relationship in stall. It is concluded that, in order to accurately calculate blade loads under conditions of retreating blade stall, the effects of lift hysteresis and negative aerodynamic torsional damping must be included, in addition to the usual nonlinearities in lift and moment coefficients. It is further concluded that a numerical integration of the differential equation (as opposed to a solution utilizing harmonics of airload) and inclusion of the effects of blade deformation are essential to achieve accurate definition of the airloads. (Author).
Download or read book Flight Investigation of Effects of Retreating blade Stall on Bending and Torsional Moments Encountered by a Helicopter Rotor Blade written by LeRoy H. Ludi and published by . This book was released on 1958 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flight tests have been conducted with a medium-size single-rotor helicopter, one blade of which was equipped with strain gages, to determine the effects of retreating-blade stall on the rotor blade bending and torsional moments during high-speed flight and pull-up maneuvers.
Download or read book Analysis of Helicopter Rotor Blade Torsional Oscillations Due to Stall written by Peter Crimi and published by . This book was released on 1975 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comparison of Three Methods for Calculation of Helicopter Rotor Blade Loading and Stresses Due to Stall written by Wayne Johnson and published by . This book was released on 1974 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Investigation of Effects of Selected Operatings Conditions on the Bending and Torsional Moments Encountered by a Helicopter Rotor Blade written by LeRoy H. Ludi and published by . This book was released on 1961 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Helicopter Blade Dynamic Loads Measured During Performance Testing of Two Scaled Rotors written by John D. Berry and published by . This book was released on 1987 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: A test to determine the performance differences between the 27-percent-scale models of two rotors for the U.S. Army AH-64 helicopter was conducted in the Langley 14- by 22-Foot Subsonic Tunnel. One rotor, referred to as the baseline rotor, simulated the geometry and dynamic characteristics of the production baseline rotor, and the other rotor, referred to as the advanced rotor, was designed to have improved hover performance. During the performance test, the dynamic pitch-link forces and blade bending and torsion moments were also measured. Dynamic data from the forward flight investigation have been reduced and are presented herein. The advanced blade set was designed to have dynamic characteristics similar to those of the baseline rotor so that test conditions would not be limited by potential rotor instability and blade resonances and so that the measured performance increments could be considered to be due purely to aerodynamic causes. Data show consistent trends with advance ratio for both blade sets with generally higher oscillatory loads occurring for the advanced blade set when compared with the baseline blade set.
Download or read book Flight Investigation of Effects of Selected Operating Conditions on the Bending and Torsional Moments Encountered by a Helicopter Rotor Blade written by LeRoy H. Ludi and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Helicopter Theory written by Wayne Johnson and published by Courier Corporation. This book was released on 2012-03-07 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Monumental engineering text covers vertical flight, forward flight, performance, mathematics of rotating systems, rotary wing dynamics and aerodynamics, aeroelasticity, stability and control, stall, noise, and more. 189 illustrations. 1980 edition.
Download or read book Flight Measurements of the Effects of Simulated Leading edge Erosion on Helicopter Blade Stall Torsional Loads and Performance written by P. Brotherhood and published by . This book was released on 1976 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Note National Advisory Committee for Aeronautics written by United States. National Advisory Committee for Aeronautics and published by . This book was released on 1958 with total page 966 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Measurements of the effects of simulated leading edge erosion on helicopter blade stall torsional loads and performance written by P. Brotherhood and published by . This book was released on 1978 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Stall Flutter of a Helicopter Rotor Blade written by Peter Crimi and published by . This book was released on 1973 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of rotor blade aeroelastic stability was carried out, using an analytic model of a two-dimensional airfoil undergoing dynamic stall and an elastomechanical representation including flapping, flapwise bending and torsional degrees of freedom. Results for a hovering rotor demonstrated that the models used are capable of reproducing both classical and stall flutter. The minimum rotor speed for the occurrence of stall flutter in hover, was found to be determined from coupling between torsion and flapping. Instabilities analogous to both classical and stall flutter were found to occur in forward flight. However, the large stall-related torsional oscillations which commonly limit aircraft forward speed appear to be the response to rapid changes in aerodynamic moment which accompany stall and unstall, rather than the result of an aeroelastic instability. The severity of stall-related instabilities and response was found to depend to some extent on linear stability. Increasing linear stability lessens the susceptibility to stall flutter and reduced the magnitude of the torsional response to stall and unstall.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Helicopter Rotor Blade Flutter and Flapwise Bending Response in Hovering written by Frank A. DuWaldt and published by . This book was released on 1959 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Note written by and published by . This book was released on 1958 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Helicopter Main Rotor Blade Phasing and Spacing on Performance Blade Loads and Acoustics written by Santu T. Gangwani and published by . This book was released on 1976 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Investigation of Effects of Selected Operatings Conditions on the Bending and Torsional Moments Encountered by a Helicopter Rotor Blade written by LeRoy H. Ludi and published by . This book was released on 1961 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:
