Probabilistic Modelling of Aircraft Response to Non-Gaussian Continuous Turbulence

This paper presents progress in the development of a unified model for the prediction of limiting gust loads. The requirement for gust loads methodologies that combine both aspects of discrete and continuous features in the airworthiness regulations is discussed. The Efficient Threshold Upcrossing method is introduced, which enables very efficient derivation of the long-term statistics of aircraft response to continuous turbulence. The method is demonstrated upon a simple free-free aircraft model for which exceedance curves of linear response are calculated and the results are compared with both theoretical curves and those derived from Monte-Carlo simulation. It is shown that the Efficient Threshold Upcrossing method will lower the computational cost of probabilistic non-linear response calculations by 2 or 3 orders of magnitude, provided that further work can verify that there is a strong correlation between the extreme values of linear and non-linear response.