Buffet-induced structural/flight-control system interaction of the X-29A aircraft

Voracek, David F.; Clarke, R.J.

doi:10.2514/3.46505

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…13), the stiffness variation can be viewed as the variation of the resonant frequency of the whole servoelastic system (! se ), equation (16) 5 ! se % ffiffiffiffiffiffiffiffi ffi K a j j m eq s ð16Þ…”

Section: Actuator Stiffness and Fcs Dynamic Characteristicsmentioning

confidence: 99%

“…The study and the characterization of this actuator performance, essentially depending on the load frequency and the closed-loop control architecture and parameters, plays a key role in the design of flyby-wire flight control systems (FBW/FCS), since harmful effects can result from the interactions between actuator, structural dynamics, and unsteady aerodynamic loads [1][2][3]. Actually, FBW aircraft envelopes are typically characterized by high speed and high angle-of-attack [4], and aeroservoelastic concerns derived from flutter, gusts, or buffeting must be predicted, compensated, and controlled to avoid performance degradation or even instability [5]. The typical approach for compensating these adverse interactions is to implement notch filters on the feedback path of the FCS inertial sensors (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Experimental assessment of the dynamic stiffness of a fault-tolerant fly-by-wire hydraulic actuator

Rito

Galatolo

2012

Proceedings of the Institution of Mechanical Engineers, Part G:

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The stiffness of an actuator depends on the closed-loop position control (architecture and parameters), on the load frequency, and, for fault-tolerant actuators, on the operative mode. The stiffness response is of basic importance for the design of actuators for primary flight controls, especially for high-performance aircrafts. Actually, during flight conditions characterized by high speed and high angle-of-attack, the dynamic interactions between aircraft structure, actuator, and aerodynamic loads can induce aeroservoelastic effects, which, if not controlled, can imply performance degradation and even instability. The study and the compensation of such concerns require the assessment of the resonant frequencies of the aeroservoelastic system, which can be performed only by characterizing the dynamic stiffness of the actuator. This article reports the experimental activities carried out for the characterization of the stiffness response of a fault-tolerant fly-by-wire actuator for the primary flight controls of a modern jet trainer, starting from the feasibility studies of the experiments up to the execution of the vibration tests. The actuator stiffness performance is evaluated in different fail-operative modes by artificially injecting hydraulic and electrical failures, and the experimental data are interpreted by means of an LTI model of the flight actuator, highlighting and discussing the effects that the failures induce on the stiffness performance.

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Section: Actuator Stiffness and Fcs Dynamic Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental assessment of the dynamic stiffness of a fault-tolerant fly-by-wire hydraulic actuator

Rito

Galatolo

2012

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The problem was rectified by reducing the pitch loop gain. Buffet induced structure control coupling was experienced in the X-29A aircraft (Voraceck and Clarke 1991). Another instance is given in Wray (1999), for F-22 aircraft, at certain flight conditions corresponding to a specific speed, altitude and AOA, higher response was recorded at feed-back sensors which could be attributed to impact of separated flow and buffeting.…”

Section: Introductionmentioning

confidence: 97%

Model updation using multiple parameters influencing servoelastic response of a flexible aircraft

Srinivasan¹,

Joshi²

2017

Advances in aircraft and spacecraft science

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In a flexible airvehicle, an assessment of the structural coupling levels through analysis and experiments provides structural data for the design of notch filters which are generally utilized in the flight control system to attenuate the flexible response pickup. This is necessitated as during flight, closed loop control actuation driven with flexible response inputs could lead to stability and performance related problems. In the present work, critical parameters influencing servoelastic response have been identified. A sensitivity study has been carried out to assess the extent of influence of each parameter. A multi-parameter tuning approach has been implemented to achieve an enhanced analytical model for improved predictions of aircraft servoelastic response. To illustrate the model updation approach, initial and improved test analysis correlation of lateral servoelastic responses for a generic flexible airvehicle are presented.

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Integrated Aeroservoelastic Optimization: Status and Direction

Livne

1999

Journal of Aircraft

107

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Buffet-induced structural/flight-control system interaction of the X-29A aircraft

Cited by 4 publications

References 3 publications

Experimental assessment of the dynamic stiffness of a fault-tolerant fly-by-wire hydraulic actuator

Experimental assessment of the dynamic stiffness of a fault-tolerant fly-by-wire hydraulic actuator

Model updation using multiple parameters influencing servoelastic response of a flexible aircraft

Integrated Aeroservoelastic Optimization: Status and Direction

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