Airborne and Ground Resonance of Hingeless Rotors

Lytwyn, R. T.; Miao, Wuxia; Woitsch, W.

doi:10.4050/jahs.16.2.2

Cited by 26 publications

(4 citation statements)

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“…It is important to highlight that in the literature there are different models to study the GR, such as including the stiffness of the blades, additional DOFs of fuselage and dynamics of shock absorbers mounted on the landing gears (Lytwyn et al., 1971; Janowski and Tongue, 1988; Jang and Chopra, 1998; Bielawa, 2006; Lee and Kim, 2010). However, the model used herein is also widely used for studying the GR (e.g., Coleman and Feingold, 1956; Gandhi and Malovrh, 1999; Bielawa 2006; Sanches et al., 2014; Bergeot et al., 2017), and it is employed in this work to introduce the idea of stabilizing a range of rotor speed using a single controller.…”

Section: Gr Dynamic Modelmentioning

confidence: 99%

“…This phenomenon typically occurs in hinged (articulated) rotors. However, helicopters using the soft-inplane hingeless (Lytwyn et al., 1971) and bearingless rotors (Jang and Chopra, 1998) are also susceptible to this problem. A classical analysis of this phenomenon was developed by Coleman and Feingold (1956) using a simple linear mechanical model.…”

Section: Introductionmentioning

confidence: 99%

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On the controllers' design to stabilize ground resonance helicopter

Silva

Bueno

Abreu

2019

Journal of Vibration and Control

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Ground resonance (GR) in helicopters is a potentially catastrophic instability commonly caused by coalescence of the regressive cyclic blade lag mode with the fuselage motion in certain rotor speed ranges. It can limit the helicopter operational envelope and the design of this type of vehicle can become a difficult task. Although a broad class of actuators allows the use of active and semi-active techniques to design feedback-based control systems, a limited number of works in the literature introduce formulations to compute the controller gain to suppress this phenomenon. Also, commonly, a control approach defines a feedback, particularly to a specific rotor speed. In this context, this work introduces an alternative methodology to design an active control system to stabilize GR of a helicopter. The proposed approach can suppress this instability in all rotor speed ranges by using only one control gain. Two strategies are proposed based on linear matrix inequalities (LMIs). The Lyapunov stability criteria are used and the unstable rotor speed is considered as an uncertain parameter to define an associated convex space. Using convex optimization, a robust control gain is computed until all the unstable rotor speed range is stabilized. Numerical simulations are carried out to demonstrate the effectiveness of this methodology. The results confirm the viability of the proposed approach to design active and semi-active controllers.

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Section: Gr Dynamic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the controllers' design to stabilize ground resonance helicopter

Silva

Bueno

Abreu

2019

Journal of Vibration and Control

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“…Ground and air resonance of hingeless rotors was studied by Donham et a/' 26 ', Lytwyn et a/' 27 ', Young et a/ 28 ', Green' 29 ', and Ellis' 30 " 31 ' who developed the general theory of the ground and air resonance of hingeless rotor helicopters. Some other investigators studied air resonance as a separate problem' 3235 '.…”

Section: Review Of Existing Analysesmentioning

confidence: 99%

Helicopter ground resonance — a spatial model analysis

Nahas¹

1984

Aeronaut. j.

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Classic theory of helicopter ground resonance studies the phenomenon on a planar model obtained by reducing the dynamic parameters of the full helicopter into the plane of rotation. In this paper the phenomenon is studied on a spatial helicopter model of six degrees of body freedom. It is found that in general there exist six regions of instability, whereas the planar theory of Coleman determines only one region. The theoretical results obtained here are verified by experiments conducted on a dynamic model of helicopter. In addition, this paper reviews all the existing analyses which have studied the problem.

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“…Numerous investigations of the ground resonance phenomenon of a helicopter have been made (Bojanowski, 1989; Bramwell, 1976; Coleman and Feingold, 1958; Dymitruk and Zerek, 1984, 1985; Dz˙ygadło and Kowaleczko, 2000; Kuras and Zerek, 1966; Lytwin et al , 1970; Mil et al , 1967; Ormison, 1991; Szabelski, 1995; Szrajer, 1989; Zerek, 1989). Usually a classical theory of the ground resonance has been applied in those papers.…”

Section: Introductionmentioning

confidence: 99%

Effect of free play in rotor blades hinges on the non‐linear ground resonance of a helicopter

Kowaleczko

Dżygadło

2002

Aircraft Engineering and Aerospace Technology

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In this paper results of numerical analysis of the ground resonance are shown. This analysis is performed making use of the complete model of the one‐main rotor helicopter. This model is adopted from flight mechanics. For the basic analysis it is assumed that the helicopter fuselage is a rigid body and the main rotor consists of four rigid blades. Each blade performs motions about its horizontal flapping hinge and vertical lagging hinge. The tail rotor is treated as a hingeless and weightless source of thrust, which equilibrates the drag moment and ensures directional control of the helicopter. For analysis of the ground resonance phenomenon, forces and moments produced by the landing gear are taken into account – their rigidity and damping are included into consideration.

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Airborne and Ground Resonance of Hingeless Rotors

Cited by 26 publications

References 0 publications

On the controllers' design to stabilize ground resonance helicopter

On the controllers' design to stabilize ground resonance helicopter

Helicopter ground resonance — a spatial model analysis

Effect of free play in rotor blades hinges on the non‐linear ground resonance of a helicopter

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