Results 181 to 190 of about 30,707 (232)
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2001
This effort was directed toward demonstration of the efficacy of a concept for mitigation of the rotor blade modulation problem in helicopter communications. An antenna is envisioned with radiating elements mounted on the rotor and rotating with it. The rf signals are coupled to the radio stationary with respect to the airframe via a coupler of unique ...
Vaughn P. Cable, Ronald J. Pogorzelski
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This effort was directed toward demonstration of the efficacy of a concept for mitigation of the rotor blade modulation problem in helicopter communications. An antenna is envisioned with radiating elements mounted on the rotor and rotating with it. The rf signals are coupled to the radio stationary with respect to the airframe via a coupler of unique ...
Vaughn P. Cable, Ronald J. Pogorzelski
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2017
The theory discussed in previous chapters is now applied to a helicopter rotor. The results are matched with published literature. A MATLAB code is given along with this book which can be used to generate results given in this chapter.
Ranjan Ganguli, Vijay Panchore
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The theory discussed in previous chapters is now applied to a helicopter rotor. The results are matched with published literature. A MATLAB code is given along with this book which can be used to generate results given in this chapter.
Ranjan Ganguli, Vijay Panchore
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Modeling and Stabilization of a Multi-Rotor Helicopter
Journal of Intelligent & Robotic Systems, 2012In this paper, a nonlinear control augmented system for a novel eight rotor helicopter is developed, in order to achieve hover flight. Simulation results underline the good performance of the proposed control strategy. Experimental tests have been performed showing the reliability of the proposed approach.
Alejandro Sámano +3 more
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Aerodynamics and aeroacoustics of helicopter main-rotor/tail-rotor interaction
5th AIAA/CEAS Aeroacoustics Conference and Exhibit, 1999Preliminary results from an ongoing effort to model the interaction aerodynamics and aeroacoustics of main- and tail rotor of a helicopter in subsonic flow are presented. The configurations studied are a) a two-blade main- and tail rotor in hover, and b) a four-blade main- and a two-blade tail rotor in climb flight.
Ahmed, S.R., Yin, J.
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A theoretical study of helicopter rotor noise
Journal of Sound and Vibration, 1969Abstract A comprehensive theoretical study of the problem of helicopter rotor noise radiation is presented. The theory includes blade slap, rotation noise and vortex noise effects. Peak spectral levels over the “vortex noise” region are shown to be due to the higher harmonics of the rotational noise.
M. V. Lowson, J. B. Ollerhead
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10th Aeroacoustics Conference, 1986
A study was made of helicopter tail rotor noise, particularly that due to interactions with the main rotor tip vortices, and with the fuselage separation mean wake. The tail rotor blade-main rotor tip vortex interaction is modelled as an airfoil of infinite span cutting through a moving vortex.
S.-T. CHOU, A. GEORGE
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A study was made of helicopter tail rotor noise, particularly that due to interactions with the main rotor tip vortices, and with the fuselage separation mean wake. The tail rotor blade-main rotor tip vortex interaction is modelled as an airfoil of infinite span cutting through a moving vortex.
S.-T. CHOU, A. GEORGE
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Actuator disc modelling for helicopter rotors
Aerospace Science and Technology, 2004Summary: The helicopter project CHANCE contains, among other developments, the quasi-steady approximation to modelling rotors with actuator discs. This reduces the cost of an unsteady simulation down to a stationary one. In testing existing approaches in the literature, the source term implementation proved to perform best, especially in forward flight:
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1973
The development of fiber reinforced resin-bonded structural composite materials has created a new degree of design flexibility for the helicopter engineer. The development and commercial availability of glass fibers, carbon or graphite fibers, and boron fibers, with their attendant widely varying stiffness properties and material densities, enable the ...
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The development of fiber reinforced resin-bonded structural composite materials has created a new degree of design flexibility for the helicopter engineer. The development and commercial availability of glass fibers, carbon or graphite fibers, and boron fibers, with their attendant widely varying stiffness properties and material densities, enable the ...
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Rotational Noise of Helicopter Rotors
The Journal of the Acoustical Society of America, 1965An analysis procedure has been developed to predict propeller rotational noise during nonuniform, as well as uniform, inflow conditions. Although many studies have been conducted since the development of Gutin's equations (NACA TM I195), none have been developed that adequately describe the near and far rotational-noise fields of a helicopter rotor ...
Robert King, Ronald G. Schlegel
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Modern helicopter rotor aerodynamics
Progress in Aerospace Sciences, 2001Abstract The helicopter rotor wake is among the most complex fluid dynamic structures being three dimensional and in many cases unsteady. The wake begins at the blade(s) where the flow can be transonic near the blade tip and undergo compressible dynamic stall. Farther down in the wake, the flow is essentially incompressible.
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