A reevaluaion of data on atmospheric turbulence and airplane gust loads for application in spectral calculations

The available information on the spectrum of atmospheric turbulence is first briefly reviewed. On the basis of these results, methods are developed for the conversion of available gust statistics normally given in terms of counts of gusts or acceleration peaks into a form appropriate for use in spectral calculations. The fundamental quantity for this purpose appears to be the probability distribution of the root-mean-square gust velocity. Estimates of this distribution are derived from data for a number of load histories of transport operations; also, estimates of the variation of this distribution with altitude and weather condition are derived from available data and the method of applying these results to the calculation of airplane gust-response histories in operations is also outlined. (author

NACA Technical Notes

From Introduction: "The results of analyses of V-G data given in references 1 to 5 have shown that the flight loads of airplanes operated in commercial transport service are influenced by operating speeds and by forecasting and dispatching practices as reflected in differences between operations during the prewar and wartime periods. The available data are summarized and the flight results are compared with the results of analyses made in references 1 to 5.

NACA Technical Reports

From Summary: "The available information on the spectrum of atmospheric turbulence is first briefly reviewed. On the basis of these results, methods are developed for the conversion of available gust statistics normally given in terms of counts of gusts or acceleration peaks into a form appropriate for use in spectral calculations. The fundamental quantity for this purpose appears to be the probability distribution of the root-mean-square gust velocity. Estimates of this distribution are derived from data for a number of load histories of transport operations; also, estimates of the variation of this distribution with altitude and weather condition are derived from available data and the method of applying these results to the calculation of airplane gust-response histories in operations is also outlined.

Estimates of probability distribution of root-mean-square gust velocity of atmospheric turbulence from operational gust-load data by random-process theory /

Airplanes.Uunder the assumpiton that the operational gust or gust-load history of an airplane is a Gaussian random process with a single parameter, the root-mean-square values, relations are derived between the probability distribution of the root-mean-square acceleration and the associated number of peak accelerations above given values. These relations are then used in the analysis of available operational gust-load data in the form of peak counts to derive estimates of the probability distributions of root-square-mean acceleration. These probability distributions are then transformed on the basis of airplane-gust-response theory in order to derive the associated probability distribution of root-mean-square gust velocity. The application of these results to the calculation of load histories is also considered briefly.Includes three errata sheets.NACA TN No. 3362.Includes bibliographical references.Airplanes.Uunder the assumpiton that the operational gust or gust-load history of an airplane is a Gaussian random process with a single parameter, the root-mean-square values, relations are derived between the probability distribution of the root-mean-square acceleration and the associated number of peak accelerations above given values. These relations are then used in the analysis of available operational gust-load data in the form of peak counts to derive estimates of the probability distributions of root-square-mean acceleration. These probability distributions are then transformed on the basis of airplane-gust-response theory in order to derive the associated probability distribution of root-mean-square gust velocity. The application of these results to the calculation of load histories is also considered briefly.Mode of access: Internet