Results 191 to 200 of about 7,948 (233)

Failure of a Helicopter Rotor

2019
Abstract Helicopter rotor blade components that included the horizontal hinge pin, the associated nut, and the locking washer were examined. Visual examination of the submitted parts revealed that the hinge pin, fabricated from 4340 steel, was broken and that the fracture face showed a flat beach mark pattern indicative of a preexisting ...
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Modern helicopter rotor aerodynamics

Progress in Aerospace Sciences, 2001
Abstract 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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Rotational Noise of Helicopter Rotors

The Journal of the Acoustical Society of America, 1965
An 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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The Control of Helicopter Rotor Vibration

The Journal of the Helicopter Association of Great Britain, 1956
The Chairman said the subject was of paramount importance to all helicopter designers, manufacturers and operators The Association had not previously had a lecture which dealt specifically with the problem and the importance of the subject meant that such a lecture was long overdue They knew that, in spite of the claims made from time to time by sundry
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The Stiff‐hinged Helicopter Rotor

Aircraft Engineering and Aerospace Technology, 1955
THE continual development of helicopter rotor systems has so far resulted in the use of about six main types, and it will be of value briefly to recapitulate their advantages and disadvantages in order to obtain a balanced picture against which the stiff‐hinged rotor can be judged.
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First Helicopters and Rotor Systems

2004
Until 1936 when the first helicopter Fw 61 of Focke Wulf came to fly, many inventers and designers tried to develop a practicable helicopter. But the designers failed due to the lack of scientific and technological knowledge so that their devices showed a very unstable flight behaviour and could hardly leave the vicinity of the airport.
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Transonic Aerodynamics and the Helicopter Rotor

1976
The fact that helicopter rotors encounter transonic aerodynamic flow problems has been recognised for several years, and with this realisation there has been considerable activity in recent years in the study of ways of improving rotor performance through blade section and tip design [1–12].
P. G. Wilby, J. Grant
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Rotor Dynamics and Helicopter Stability

Aircraft Engineering and Aerospace Technology, 1963
The component of velocity, μ0ΩR, along the x‐axis is specified, and also X, the angle of inclination of the flight path. The concept of the ‘internal’ and ‘external’ parameters of the motion is introduced, the ‘internal’ parameters consisting of certain combinations of the control and flapping angles θ0, θ1, θ2, β0, β1, β2 and the ‘external ...
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Development and dynamics of a 2SPU+UPU+SP parallel rotor of helicopter

Aerospace Science and Technology, 2021
Zefeng Chang, Nijia Ye
exaly  

Research on Helicopter Rotor Noise

1978
Abstract : Research was conducted on aspect of noise generation by helicopters. A general review of helicopter noise was prepared and published as one part of the work. Methods were developed for the analysis of high frequency broadband noise from rotors.
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