Tip Vortex Conservation on a Helicopter Main Rotor Using Vortex-Adapted Chimera Grids

AIAA Journal ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 2062-2074 ◽  
Author(s):  
Markus Dietz ◽  
Manuel Keßler ◽  
Ewald Krämer ◽  
Siegfried Wagner
Keyword(s):  
Tip Vortex ◽  
Main Rotor ◽  
Helicopter Main Rotor

scholarly journals MATHEMATICAL MODELS OF THE RADAR SIGNAL REFLECTED FROM A HELICOPTER MAIN ROTOR IN APPLICATION TO INVERSE SYNTHESIS OF ANTENNA APERTURE

2019 ◽  
Vol 22 (3) ◽  
pp. 74-87 ◽  
Author(s):  
Sergey R. Heister ◽  
Thai T. Nguyn
Keyword(s):  
Mathematical Models ◽  
Vertical Plane ◽  
Rotor Blades ◽  
Radar Signal ◽  
Main Rotor ◽  
Antenna Aperture ◽  
Radar Images ◽  
Aerial Vehicles ◽  
Propeller Blades ◽  
Helicopter Main Rotor

Introduction. The basis for solving the problem of aircraft recognition is the formation of radar portraits, reflecting the constructive features of aerial vehicles. Portraits, which are radar images of the propellers of aerial vehicles, have high informativeness. These images allow us to distinguish the number and relative position of the propeller blades, as well as the direction of its rotation. The basis for obtaining such images are mathematical models of reflected signals. Objective. The aim of this paper is to develop mathematical models of the radar signal reflected from the helicopter main rotor applied to inverse synthetic aperture radar (ISAR). Methods and materials. ISAR processing is used to produce a radar image of a propeller in a radar with a monochromatic probing signal. The propeller blades in the models are approximated by different geometric shapes. The models used to describe the reflection from the propellers of helicopters and fixed-wing aircraft have significant differences. In the process of moving each blade of the helicopter main rotor makes characteristic movements (flapping, dragging, feathering), as well as bends in a vertical plane. Such movements and bendings of the blades are influence the phase of the signal reflected from the main rotor. It is necessary to take the phase change of the reflected signal into account as accurately as possible when developing an ISAR algorithm for imaging the main rotor. Results. We found that in the centimeter wavelength range the mathematical model of the signal reflected from the helicopter main rotor as a system of blades is most accurately described by representing each blade with a set of isotropic reflectors located on the main rotor’s blade leading and trailing edges. Taking into account the flapping movements and curved shapes of the blades in the model allows you to get as close as possible to the features of the real signal. Conclusion. The developed model which takes into account the flapping movements and bends of the helicopter main rotor blades can be used to improve the ISAR algorithms providing the radar imaging of aerial vehicles.

Failures of bolts in helicopter main rotor drive plate assembly due to improper application of lubricant

2003 ◽  
Vol 10 (4) ◽  
pp. 443-451 ◽  
Author(s):  
N. Eliaz ◽  
G. Gheorghiu ◽  
H. Sheinkopf ◽  
O. Levi ◽  
G. Shemesh ◽  
...  
Keyword(s):  
Main Rotor ◽  
Rotor Drive ◽  
Helicopter Main Rotor ◽  
Plate Assembly

scholarly journals Design and Physical Prototyping of a Novel Braking System for a Helicopter Rotor

Designs ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 40
Author(s):  
Julian D. Booker ◽  
Richard J. Lock ◽  
David Drury
Keyword(s):  
Position Control ◽  
Control Strategies ◽  
Main Rotor ◽  
Technology Readiness Level ◽  
Readiness Level ◽  
Electromechanical Device ◽  
And Performance ◽  
Helicopter Main Rotor ◽  
And Control ◽  
And Storage

The aim of this paper was to demonstrate the improved functionality and performance of an electromechanical brake for a helicopter main rotor, which to date has been hydraulically actuated using a disc brake and caliper arrangement. Increasingly, designers seek higher performing solutions to traditional problems through the integration of modern actuation and control strategies. This electromechanical device is required to constrain the helicopter tail rotor shaft protruding from the main rotor gearbox to allow safe taxiing and storage of the helicopter. A systematic and rigorous design methodology was used to converge on an effective solution which satisfied a very demanding specification. The design was further detailed and optimized, leading to the development of a prototype at a high technology readiness level that was tested within a bespoke rig, simulating the torque requirements found on a helicopter main rotor using the torque and position control. The design was shown to meet the required holding torque whilst providing additional functionality of continuous holding capability and meeting the challenging volumetric constraints.

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