Some aspects of aircraft response to atmospheric turbulence

Aspects of the requirements for and the calculation of design loads due to atmospheric disturbances are discussed. Special attention has been paid to the relation between discrete gusts and continuous turbulence. It is recommended that a worst case gust model, as described in this report, be further developed.

The generation of a random process with a spectrum with fractional power

A method is described to generate a random Gaussian process with a power spectrum with fractional power, for example the von Karman spectrum for atmospheric turbulence. The method uses digital filtering of a white noise process and it is based on the use of fractional derivatives. An algorithm to generate the process is presented.

Aircraft design loads due to non-stationary atmospheric turbulence patches

In this report it is assumed that atmospheric turbulence appears in patches and that within the patches the turbulence can be described.as a modulated Gaussian process. The patch lengths have a certain probability density function. Load exceedance curves and design loads for various aircraft models for this turbulence model are compared with...

A non-stationary model for atmospheric turbulence patches, for the prediction of aircraft design loads

In this report a model for atmospheric turbulence is proposed. It is assumed that atmospheric turbulence appears in patches and that within the patches the turbulence can be described as a modulated Gaussian process. Statistical properties of this model and of atmospheric turbulence are compared. Using data from various sources a probability...

Equations for the response of an airplane to non-stationary atmospheric turbulence patches

In this report a method is described to calculate the load exceedance curve for a linear system having a finite, modulated Gaussian process as input. The derivation is based on the use of ensemble averages, defined as the expected values at a certain point of time. The equations can be used for any airplane-transfer function for which the Power...

Comparison between the statistical discrete gust method and the power spectral density method

The Power Spectral Density method and the Statistical Discrete Gust Method to calculate aircraft design loads due to atmospheric turbulence are compared qualitatively and quantitatively on the basis of the load exceedance curves for certain aircraft models. It is shown that both methods are related to each other, giving the same results for...