Full-scale wind-tunnel pressure measurements of an F/A-18 tail during buffet

Pettit, Chris L.; Brown, Dansen; Banford, Michael; Pendleton, Ed

doi:10.2514/3.47069

Cited by 15 publications

(7 citation statements)

References 6 publications

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“…Since the results reported for this test are not being compared to other model or aircraft data, the dimensional form is used. In depth studies on buffet pressure characteristics and vertical tail buffeting have been performed on full-scale and model-scale F-18 vertical tails [1][2][3][5][6][7][8][9][10][11][12][13].…”

Section: General Buffet and Buffeting Characteristics Of The Wind-tunmentioning

confidence: 99%

“…For the purpose of understanding the buffeting problem, several programs have focused on quantifying the buffet loads by acquiring response measurements and surface pressures on the vertical tails of scaled models in a wind-tunnel and on an actual aircraft during flight [1][2][3][5][6][7][8][9][10][11][12][13]. In general, the results of these studies are published as spectra and pressure coefficients for the inboard and outboard surface of the tail.…”

Section: Introductionmentioning

confidence: 99%

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Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program

Robert

1997

SPIE Proceedings

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A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASALangley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. Buffeting alleviation results when using the rudder are presented for comparison. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

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Section: General Buffet and Buffeting Characteristics Of The Wind-tunmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program

Robert

1997

SPIE Proceedings

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“…Another approach is to alleviate buffet loads by altering the flow field. Fo r example, fences have been attached to the leading edge extensions (LEX) of the F/A-18, where the vortices are generated, in an attempt to reduce buffet loading 3,4 However, these passive modifications have only limited success since they are only effective at specific flight conditions. A better approach is to combine a number of these passive techniques to increase the fatigue life of components subject to buffeting.…”

Section: Introductionmentioning

confidence: 99%

Next Generation Active Buffet Suppression System

Galea¹,

Ryall

Henderson

et al. 2003

AIAA International Air and Space Symposium and Exposition: The Next 100 Years

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Buffeting is an aeroelastic phenomenon that is common to high performance aircraft, especially those with twin vertical tails like the F/A-18, at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. This paper describes an international collaborative research activity among Australia, Canada and the United States involving the use of active structural control to alleviate the damaging structural response to these loads. The research program is being coordinated by the Air Force Research Laboratory (AFRL) and is being conducted under the auspices of The Technical Cooperative Program (TTCP). This truly unique collaborative program has been developed to enable each participating country to contribute resources toward a program that coalesces a broad range of technical knowledge and expertise into a single investigation. This collaborative program is directed toward a fullscale test of an F/A-18 empennage, which is a n extension of an earlier initial test. The current program aims at applying advanced directional piezoactuators, the aircraft rudder, switch mode amplifiers and advanced control strategies on a fullscale structure to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration.

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“…Vortex control has included blowing and sucking flow from various ports on the aircraft and at various rates [9][10][11] , attaching different size and shape leading edge extensions (LEX) 12 , and attaching fences 3,4 to these LEX. These changes have had limited success since they are effective only at specific flight conditions.…”

Section: Past Alleviation Techniquesmentioning

confidence: 99%

“…These tests were designed to characterize the flow mechanism and to quantify the unsteady differential pressures acting on the vertical tails during high-angle-of-attack maneuvers [1][2][3][4][5][6][7] . The major findings of these tests were: 1) that the buffet pressures vary with flight conditions; 2) that the buffeting (response of the tail) varies with flight conditions; and 3) that the frequency spectra scale with Strouhal number.…”

Section: Introduction the Problemmentioning

confidence: 99%

Contributions to active buffeting alleviation programs by the NASA Langley Research Center

Moses

1999

40th Structures, Structural Dynamics, and Materials Conference and Exhibit

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Buffeting is an aeroelastic phenomenon which plagues high performance aircraft, especially those with twin vertical tails like the F/A-18, at high angles of attack. This buffeting is a concern from fatigue and inspection points of view. By means of wind-tunnel and flight tests, this phenomenon is well studied to the point that buffet loads can be estimated and fatigue life can be increased by structural enhancements to the airframe.

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Full-scale wind-tunnel pressure measurements of an F/A-18 tail during buffet

Cited by 15 publications

References 6 publications

Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program

Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program

Next Generation Active Buffet Suppression System

Contributions to active buffeting alleviation programs by the NASA Langley Research Center

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