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Loeve, W. (author), van den Dam, R.F. (author)
The NLR in the Netherlands renders scientific support and technical assistance for the design and operation of aircraft and spacecraft. The approach of NLR can be characterized by integration of experimental and theoretical investigations. For this an integrated computer and terminal network has been developed that links both NLR laboratory...
report 1983
document
Noback, R. (author)
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...
report 1975
document
Arendsen, P. (author), van Dalen, F. (author), Bill, C. (author), Rothwell, A. (author)
In a joint research project between the National Aerospace Laboratory (NLR) and the Faculty of Aerospace Engineering of Delft University of Technology (TUD) a multi-level system for the preliminary design of aircraft structures has been developed. The present system is essentially an extension of the existing Aircraft Design and Analysis System ...
report 1995
document
van den Dam, R.F. (author)
An interactive computer program system has been developed which provides induced-drag analysis, optimization and configuration-design capabilities. The program system employs subsonic far-field (Trefftzplane) analysis, and novel mathematical formulations of the constrained optimization problems which are based on calculus of variations. The...
report 1982
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van der Vooren, J. (author), van der Kolk, J.T. (author), Slooff, J.W. (author)
A description will be presented of a computer program system that is being used for the prediction of aircraft steady aerodynamic characteristics. Properties of the system are described from two different viewpoints. One is that of the aerodynamic designer, who needs an information system to predict lift, moment and drag characteristics and to...
report 1982
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van den Dam, R.F. (author)
The central issue discussed in this paper is how a designer may profit from the use of mathematical simulation and optimization techniques. These techniques can be useful tools to support the designer in solving his design problem. The place and the potential of these techniques in the design process, as well as their use by the designer, are...
report 1985
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Noback, R. (author)
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...
report 1978
document
Vink, W.J. (author), de Jonge, J.B. (author)
The present report is part of a "Manual" on aircraft loads, that is being prepared by NLR. It contains a computer program, to be used in combination with "MATLAB4 for Windows" (Student Edition) software, to study aircraft loading due to turbulence. It includes a simple aircraft response model with two rigid and three flexible symmetric degrees...
report 1997
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Noback, R. (author)
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...
report 1976
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de Jonge, J.B. (author)
Fail-safety or damage tolerance i s generally considered as a highly desirable and in some countries as anobligatory property of transport aircraft structures. Recently the USAP issued a detailed requirement on damage tolerance. In the present report various aspects of damage tolerance are discussed with specific reference to the USAP...
report 1976
document
Noback, R. (author)
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.
report 1993
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Loeve, W. (author), van den Dam, R.F. (author)
NLR has developed an infrastructure of hardware and software for support of aerodynamic design of aircraft. Organizational and technical aspects of this development are described.
report 1983
document
Noback, R. (author)
The Deterministic Power-Spectral-Density method can be derived from the Design Envelope Analysis of the continuous P.S.D.-method. It provides a method to determine a deterministic function that gives a maximum response equal to the P.S.D.-design load for linear systems. The P.S.D.-design load is undefined for nonlinear systems. In this report a ...
report 1992
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van den Dam, R.F. (author)
The use of numerical simulation and optimization techniques is rapidly expanding in all fields of engineering design. The place and the potential of these techniques in the design process, as well as their use by the designer, are discussed. The principles underlying these techniques are outlined and an overall view is given of the various...
report 1985
document
Noback, R. (author)
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...
report 1976
document
Noback, R. (author), Blaauboer, C. (author)
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...
report 1980
document
Boerstoel, J.W. (author)
A survey of numerical methods for the calculation of inviscid Euler flows is presented. This survey has been prepared for AGAKD FDP WGOT: "Test cases for steady inviscid transonic or supersonic flows". The survey is augmented by a short assessment of the usefulness of the methods. For aerodynamic applications, the existing methods are in a...
report 1983
document
Slooff, J.W. (author)
Examples are discussed of the application of computational methods in aerodynamic design problems involving interference. Amongst these are: subsonic wing-body, sting support, pylon-nacelle and pylon-store interference, high-lift devices, induced drag minimization through constrained optimization in the Treftz-plane and transonic wing-fuselage...
report 1983
document
Noback, R. (author)
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...
report 1989
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Noback, R. (author)
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.
report 1993
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