Derivation and Analysis of Loading Spectra for USAF Aircraft.
Final rept. Jun 73-Mar 74,
AERONAUTICAL SYSTEMS DIV WRIGHT-PATTERSON AFB OHIO
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The report details a methodology for deriving a random flight-by-flight spectrum for a close air support type aircraft. In developing this spectrum it was necessary to first determine the stresses and their occurrences by using an all points in the sky type loads analysis. The developed random spectrum was compared with a low-high-low block type spectrum using crack growth analysis and was found to give more conservative results. The baseline spectrum was regenerated with different random sequences to determine the effect of stress and flight ordering. Another study was made to determine if omitting the ground loads affected the life. Both of these studies indicated crack growth life was minimally affected.