Results 131 to 140 of about 1,267 (185)
Some of the next articles are maybe not open access.
Technology, Law and Insurance, 2000
The vital part of a helicopter is no doubt the main rotor. If the rotor fails, the helicopter will fall. Therefore rotor blades are checked very carefully and replaced or repaired if they show any indication of damage which might lead to failure. A case is reported where a rotor blade failed after a long service time without any prior indications of ...
Rolf Kieselbach, Georg Soyka
openaire +1 more source
The vital part of a helicopter is no doubt the main rotor. If the rotor fails, the helicopter will fall. Therefore rotor blades are checked very carefully and replaced or repaired if they show any indication of damage which might lead to failure. A case is reported where a rotor blade failed after a long service time without any prior indications of ...
Rolf Kieselbach, Georg Soyka
openaire +1 more source
Parallel computing for helicopter rotor design
[1993] Proceedings The 2nd International Symposium on High Performance Distributed Computing, 2002The high-speed computing (HSC) program was established in 1986 within Boeing Computer Services (BCS) to provide a prototypical environment which could be used to study the problem of integrating new computing technologies into Boeing. This paper summarizes work within the HSC program on parallel computing and concentrates on one application area ...
Joseph W. Manke +2 more
openaire +1 more source
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
openaire +1 more source
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
openaire +1 more source
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.
openaire +2 more sources
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
openaire +1 more source
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
openaire +1 more source
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:
openaire +3 more sources
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 ...
openaire +1 more source
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 ...
openaire +1 more source
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 ...
openaire +1 more source
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 ...
openaire +1 more source
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.
openaire +1 more source