Results 191 to 200 of about 30,707 (232)

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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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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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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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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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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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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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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Advances in Helicopter Rotor Technology

2004
Since the beginning of the helicopter development (see “First Helicopters and Rotor Systems”) there was a need to place hinges and bearings as close to the rotor center as possible to guarantee low rotor stiffness and hence good control characteristics at low cabin vibrations.
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Development and dynamics of a 2SPU+UPU+SP parallel rotor of helicopter

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

Stability Derivatives of Helicopter Rotors

1938
At present there are only three published papers dealing with the stability of helicopters, all based on helicopters with rigid rotors. Since all rotors are, in practice, constructed with the blades free to "flap", these analyses are not sufficiently general.
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