Results 181 to 190 of about 30,315 (234)
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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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Unsteady flow through helicopter rotors
ZAMP Zeitschrift für Angewandte Mathematik und Physik, 1958Es wird ein Beitrag geliefert zur Stutzung der schon fruher geausserten Uberzeugung, dass nichtstationare Stromungsanteile das Schwingungsverhalten und die aeroelastische Stabilitat von Helikopter-Drehflugeln wesentlich beeinflussen konnen. Die Untersuchung betont besonders den Dampfungsverlust, welcher sich aus den entlang der Spannweite eines ...
Holt Ashley +2 more
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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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Modular Multi-Rotor Helicopter Platforms
Solid State Phenomena, 2015The results presented in this paper describe a practicable solution to multi-rotor platforms constructed and put together with standardized components to allow flexibility and customizability. The extensive utilization of universal parts supports an easy introduction of changes in case of necessary design alterations and speeds up the whole process ...
Kristjan Tiimus, Mart Tamre
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Low vibration helicopter rotor
The Journal of the Acoustical Society of America, 1990A low vibration helicopter rotor including a four-bar linkage arrangement which permits the straight line connecting the center of gravity of each pair of diametrically opposed rotor blades to intersect the rotor hub geometrical center at all cyclic conditions.
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Helicopter Rotor Spar Production
Aircraft Engineering and Aerospace Technology, 1964Helicopter rotor blades arc subject to a considerable degree of Hexing and vibration when in service, and since scratches and other surface defects can give rise to fatigue cracking it is of the utmost importance that blade members should be free from such faults.
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Electromagnetic Backscattering of Helicopter Rotor
Electromagnetics, 1996ABSTRACT The scattering problem of electromagnetic waves from a helicopter rotor is addressed in this work using the physical optics (PO) and physical theory of diffraction (PTD) equivalent currents techniques with quasi-stationary method. Experimental results indicated that, in the far zone, the field can be considered as harmonic and expressions for ...
Sheau-Shong Bor +4 more
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Damper means for helicopter rotors
The Journal of the Acoustical Society of America, 1981A helicopter rotor includes a rotor head having, for each of a plurality of rotor blades, an elastomeric bearing and a damper that is arranged to provide controlled restraint of rotor blade movement in both the flap and lead/lag planes. The damper can be arranged to exhibit either substantially equal stiffness in both operational planes or any desired ...
Alan Waldington, Alfred C. Martin
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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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Tandem Rotor Helicopter Control
2018In this chapter, we study the dynamic analysis and control design for the tandem rotor 3-DOF helicopter platform. We utilized the MATLAB/Simulink software to integrate with the Quarc software for the control system. The system mimics a Chinook helicopter, of which the build consists of a base to which an arm is mounted, two motor-driven propellers ...
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