Worst case gust shapes for atmospheric turbulence with known spectrum

A worst case gust shape has been derived for turbulence or gust patches, assuming only that the average spectrum of such patches is known. The maximum value of the response can be calculated quite easily. The result differs from the PSD-method. Some examples of worst case inputs and outputs are given, also for nonlinear systems.

Definition of P.S.D.-design loads for nonlinear aircraft

The Power Spectral Density (P.S.D.)-method is used to define design loads due to atmospheric turbulence. The design loads are calculated using linear transfer functions. These methods can not be used if the equations describing the behaviour of the aircraft are nonlinear. One method to define design loads for a nonlinear aircraft is by means of...

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.

Estimation of load exceedances of an aircraft undercarriage with nonlinear properties excitated by random runway unevenness

In this report various methods to describe a landing gear with nonlinear properties and excitated by random runway unevenness during taxying have been investigated. The results of calculations have been compared to measured results from an analog computer simulation. The mean behaviour, standard deviations and power spectra, can be described...

The determination of gustloads on nonlinear aircraft using a Power Spectral Density approach

Design loads for nonlinear aircraft, i.e. aircraft with gust alleviation system or yaw dampler, cannot be established with the Power Spectral Density method. The only method available is by means of computer simvilation. Methods to approximate load exceedance curves of nonlinear aircraft are proposed in this report. For the derivation of the...

Some methods for the derivation of taxying loads for undercarriages with linear or nonlinear properties.

Methods that are used or probably could be used for the establishment of taxying loads are presented and discussed. The methods are straightforward for undercarriages with linear properties. For undercarriages with nonlinear properties methods based on the use of equivalent gains are promising, but still have to be verified.

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...

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...