Topic
Helicopter rotor
About: Helicopter rotor is a research topic. Over the lifetime, 7201 publications have been published within this topic receiving 77045 citations. The topic is also known as: rotor blades & Rotor.
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Dissertation•
01 Jan 1975
TL;DR: In this article, the authors present an approach for the design of an unmanned aerial vehicle (UAV) based on the concept of a self-healing sensor network, which is a technique from aeronautics.
Abstract: Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
187 citations
01 Nov 1981
TL;DR: In this paper, a two dimensional section of a helicopter main rotor blade was tested in an acoustic wind tunnel at close to full-scale Reynolds numbers to obtain boundary layer data and acoustic data for use in developing an acoustic scaling law and testing a first principles trailing edge noise theory.
Abstract: A two dimensional section of a helicopter main rotor blade was tested in an acoustic wind tunnel at close to full-scale Reynolds numbers to obtain boundary layer data and acoustic data for use in developing an acoustic scaling law and testing a first principles trailing edge noise theory. Results were extended to the rotating frame coordinate system to develop a helicopter rotor trailing edge noise prediction. Comparisons of the calculated noise levels with helicopter flyover spectra demonstrate that trailing edge noise contributes significantly to the total helicopter noise spectrum at high frequencies. This noise mechanism is expected to control the minimum rotor noise. In the case of noise radiation from a local blade segment, the acoustic directivity pattern is predicted by the first principles trailing edge noise theory. Acoustic spectra are predicted by a scaling law which includes Mach number, boundary layer thickness and observer position. Spectrum shape and sound pressure level are also predicted by the first principles theory but the analysis does not predict the Strouhal value identifying the spectrum peak.
174 citations
TL;DR: In this paper, a finite element model of a geared rotor system on flexible bearings has been developed, which includes the rotary inertia of on shaft elements, the axial loading on shafts, flexibility and damping of bearings, material damping and the stiffness and the damping in gear mesh.
Abstract: A finite element model of a geared rotor system on flexible bearings has been developed. The model includes the rotary inertia of on shaft elements, the axial loading on shafts, flexibility and damping of bearings, material damping of shafts and the stiffness and the damping of gear mesh. The coupling between the torsional and transverse vibrations of gears were considered in the model. A constant mesh stiffness was assumed. The analysis procedure can be used for forced vibration analysis geared rotors by calculating the critical speeds and determining the response of any point on the shafts to mass unbalances, geometric eccentricities of gears, and displacement transmission error excitation at the mesh point. The dynamic mesh forces due to these excitations can also be calculated. The model has been applied to several systems for the demonstration of its accuracy and for studying the effect of bearing compliances on system dynamics.
171 citations
TL;DR: In this article, genetic programming is applied to the identification of the nonlinear structure of a dynamic model from experimental data, where the model structure may be described either by differential equations or by a block diagram.
169 citations
TL;DR: In this article, the density fields of the blade tip vortices from a helicopter in hover flight were visualized by a technique which does not require any installation on the helicopter or close to it.
Abstract: Density fields of the blade tip vortices from a helicopter in hover flight were visualized by a technique which does not require any installation on the helicopter or close to it. The results illustrate an encouraging prospect for the applicability of the technique. It offers the capability of at least qualitative investigations of unsteady density fields even in full-scale flight tests. The underlying principle is briefly described in this article and an extension to a three-dimensional quantitative technique by using multiple cameras is outlined.
169 citations