Results 181 to 190 of about 15,084 (235)

Helicopter Rotor Blades

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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Helicopter Rotor Blade Flapping and Bending

Aircraft Engineering and Aerospace Technology, 1957
THE problem of calculating the motion of a helicopter blade presents many difficulties. Probably the most serious is the lack of knowledge of the aerodynamic forces acting on a blade, but a second major difficulty arises when the equations of motion have to be solved.
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The phenomenon of helicopter rotor blade sailing

Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 1999
Blade sailing is an aeroelastic phenomenon affecting helicopter rotors when rotating at low speeds in high wind conditions. This is a potentially dangerous blade motion and the excessive flapwise tip deflections generated endanger the airframe, the flight crew and any personnel working close to the aircraft.
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Unsteady Air Loads on Helicopter Rotor Blades

The Journal of the Royal Aeronautical Society, 1964
An appropriate introduction to the topic of this lecture is the following comment taken from Cierva's third and last lecture presented before this Society in 1935:“Perhaps the most irritating of the secondary difficulties met with in the Autogiro development have been those of a dynamical nature.
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Boundary Layer Control on Helicopter Rotor Blades

Aircraft Engineering and Aerospace Technology, 1967
THE possibility of applying boundary layer control by suction at the trailing edge to reduce the profile drag of a helicopter rotor blade using centrifugal forces to provide the suction was investigated. It was shown theoretically that it is possible to use this method of suction, and that it is advantageous to suck at the trailing edge if the drag ...
Albert N. Debono, Maurice G. Pollard
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Orthogonal Blade-Vortex Interaction on a Helicopter Tail Rotor

AIAA Journal, 2008
The orthogonal blade-vortex interaction has been simulated using unsteady Reynolds-averaged Navier-Stokes equations with turbulence closure equations. The cases investigated are relative to an interaction between a lifting blade at a high angle of attack and an orthogonal vortex that travels either head-on or at 45 deg to the leading edge.
Filippone, Antonio, Afgan, Imran
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Subsonic and Transonic Potential Flow over Helicopter Rotor Blades

AIAA Journal, 1972
Compressible potential flows over nonlifting, hovering helicopter blades are described by suitable linear and nonlinear equations of motion for subsonic and transonic cases, respectively. Analytical and numerical results are presented for the linearized subsonic three-dimensional flow in the tip region.
F. CARADONNA, M. ISOM
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Crack Propagation in Helicopter Rotor Blades

1971
Design criteria are presented for the residual strength and life of fatigue loaded helicopter structures. The crack propagation rate methods and data are reviewed, and a bilinear semilog method is shown to be most accurate for predicting residual life. The methods developed are compared with full scale rotor blade fatigue data.
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Analysis of Helicopter Rotor Blade Stall Flutter

Journal of Aircraft, 1974
A study of rotor blade aeroelastic stability is carried out, using an analytic model of a two-dimensional airfoil undergoing dynamic stall and an elastomechanical representation including flapping, flapwise bending, and torsional degrees of freedom. Results for a hovering rotor demonstrate that the models are capable of reproducing both classical and ...
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Micro-Doppler Signatures of Helicopter Rotor Blades

2014
The work presented in this chapter has shown how to take advantage of the microDoppler features of the rotary parts of a helicopter. Traditionally, analysis of the amplitude variations of the target echo returns have been used in order to separate fixed wing and rotary wing aircraft.
Karl Erik Olsen, Terje Johnsen, Øystein Lie-Svendsen, Børge Torvik   +3 more
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