Open Access
Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades
John C. Houbolt,George W Brooks +1 more
TLDR
In this article, the differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper.Abstract:
The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper. Special attention is given the terms which are not included in previous theories. These terms are largely coupling-type terms associated with the centrifugal forces. Methods of solution of the equations of motion are indicated by selected examples.read more
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Rotor performance enhancement via localized pitch control and its effects on hub vibrations and pitch link loads
TL;DR: In this paper, localized pitch control (LPC) is proposed to enhance rotor performance and reduce vibration levels at the rotor hub by introducing local blade pitch variations at specific azimuthal locations.
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An Analytical Investigation of the Trapeze Effect Acting on a Thin Flexible Ribbon
Jérôme Sicard,Jayant Sirohi +1 more
TL;DR: In this article, the extensional-torsional coupling due to the trapeze effect acting on a thin flexible ribbon subjected to combined tension and torsion is analyzed.
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On the dynamic response of a hingeless helicopter rotor blade
TL;DR: In this paper, the coupled, steady-state dynamic response of the Bo 105 hingeless helicopter rotor blade is investigated at forward flight for different advance ratios without small-angle assumption, and the velocity distributions are generalized and the torsional deformation is introduced to modify the total blade twist for deriving the corresponding angle of attack.
Aeromechanical Evaluation of Smart-Twisting Active Rotor
Joon W. Lim,D. Douglas Boyd,Frauke Hoffman,Berend G. van der Wall,Do-Hyung Kim,Sung N. Jung,Young H. You,Yasutada Tanabe,Joëlle Bailly,Caroline Lienard,Yves Delrieux +10 more
TL;DR: In this paper, the Smart-Twisting Active Rotor (STAR) was evaluated for performance improvement, vibration reduction, and noise alleviation in various flight conditions including hover, descent, moderate to high speed level flights, and slowed rotor high advance ratio.
References
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Book
Theory of elasticity
TL;DR: The theory of the slipline field is used in this article to solve the problem of stable and non-stressed problems in plane strains in a plane-strain scenario.
Simplified Procedures and Charts for the Rapid Estimation of Bending Frequencies of Rotating Beams
TL;DR: In this paper, a Rayleigh energy approach utilizing the bending mode of the nonrotating beam in the determination of the bending frequency of the rotating beam was presented, which is evaluated and is found to give good practical results for helicopter blades.