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Analysis of F/A-18 Tail Buffet Data Acquired in the 80- by 120-Foot Wind TunnelTail buffet studies were conducted on a full-scale, production, F/A-18 fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center at Moffett Field, California. Tail buffet data were acquired over an angle-of-attack range of +20 deg to +40 deg, a side-slip range of -16 deg to + 16 deg, and at wind speeds up to 100 knots. The maximum speed corresponds to a Reynolds number of l2.3 x l0(exp 6) based on mean aerodynamic chord and a Mach number of 0. 15. The port, vertical tail fin was instrumented with ninety-six surface-pressure transducers, arranged in six by eight arrays, on each side of the fin. ne aircraft was also equipped with a removable Leading-Edge Extension (LEX) fence whose purpose is to reduce tail-buffet loads. Current analysis methods for the unsteady aerodynamic pressures and loads are described. Only results for the zero side-slip condition are to be presented, both with and without the LEX fence. Results of the time-averaged, power-spectral analysis are presented for the tail fin bending moments which are derived from the integrated pressure field. Local wave velocities on the tail surfaces are calculated from pressure correlations. It was found that the LEX fence significantly reduces the magnitude of the root-mean-square pressures and bending moments. Scaling and repeatability issues are addressed by comparing the present full scale results for pressures at the 60%-span and 45%-chord location with previous full-scale F/A-18 tail-buffet test in the 80- by 120- Foot Wind Tunnel, and with several small-scale tests. The comparisons show that the tail buffet frequency scales very well with tail chord and free-stream velocity, and that there is good agreement with the previous full-scale test. Root-mean-square pressures and power spectra do not scale as well as the frequency results. Addition of a LEX fence caused tail-buffet loads to be reduced at all model scales.
Document ID
20010051288
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
James, Kevin D.
(Sterling Federal Systems, Inc. Moffett Field, CA United States)
Meyn, Larry A.
(NASA Ames Research Center Moffett Field, CA United States)
Schmitz, Fredric H.
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Aerodynamics
Meeting Information
Meeting: SAE Aerospace Atlantic Conference
Location: Dayton, OH
Country: United States
Start Date: April 18, 1994
End Date: April 22, 1994
Sponsors: Society of Automotive Engineers, Inc.
Funding Number(s)
PROJECT: RTOP 505-59-30
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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