4.7% F-15 Bending

This data was also taken from WL-TM-97-3084.  The bending RMS response of the tails in Figure 5 shows an increase with angle of attack increase.  This type of response does not show any signs of a tuned response due to the flow.  Random fluctuation intensities due to the turbulent wake of the fuselage and wake-like vortex show this type of increase with angle of attack. The 1st bending mode frequency is 48 Hz and the 2nd bending mode frequency is 229 Hz.  The flow spectral peak frequency needs to be found to determine what is forcing the observed tail responses.    Empirical Prediction vs. Test Data

 F-15 Tail Buffet Alleviation Results
F-15 Velocity Spectra    Frequency vs. Velocity    Reduced Frequency
4.7% F-15 Torsion    4.7% F-15 Bending    Empirical Prediction vs. Test Data