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L. B. Schiff

Bio: L. B. Schiff is an academic researcher. The author has contributed to research in topics: Aerodynamics & Flight dynamics. The author has an hindex of 1, co-authored 1 publications receiving 58 citations.

Papers
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01 Jan 1984
TL;DR: The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of non linear functional expansions.
Abstract: Basic concepts involved in the mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers are reviewed. The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of nonlinear functional expansions. Extensions of the analysis through its natural connection with ideas from bifurcation theory are indicated.

58 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors present a review of reduced-order aerodynamic models for aircraft stability and control analysis, including linear and nonlinear indicial response methods, Volterra theory, radial basis functions, and a surrogate-based recurrence framework.

109 citations

Journal ArticleDOI
TL;DR: An approach for the generation of aerodynamic tables using computational fluid dynamics is discussed, and a method to efficiently reduce the number of high-fidelity analyses is reviewed, using a kriging-based surrogate model.

106 citations

Journal ArticleDOI
TL;DR: The results show that the ROMs can accurately model the unsteady loads in response to slow and fast pitch and plunge motions by comparison of the model output with time-accurate CFD simulations.
Abstract: The generation of reduced-order models (ROM) for the evaluation of unsteady and nonlinear aerodynamic loads are investigated. The ROM considered is an indicial theory based on the convolution of step functions with the derivative of the input signal. The step functions are directly calculated using the results of RANS simulations and a grid movement tool. Results are reported for a two dimensional airfoil and a UCAV configuration. Wind tunnel data are first used to validate the prediction of static and unsteady coefficients at both low and high angles of attack, with good agreement obtained for all cases. The generation of the aerodynamic models is described. The focus of the paper shifts to assess the validity of studied ROMs with respect to new maneuvres. This is accomplished by comparison of the model output with time-accurate CFD simulations. The results show that the ROMs can accurately model the unsteady loads in response to slow and fast pitch and plunge motions.

81 citations

Journal ArticleDOI
TL;DR: In this paper, a 65-deg swept delta wing was tested in both the Institute for Aerospace Research 2 X 3 m low-speed wind tunnel and the 7 X 10 ft Subsonic Aerodynamic Research Laboratory facility at Wright-Patter son Air Force Base.
Abstract: Dynamic wind-tunnel test results of a 65-deg swept delta wing are reviewed. These tests involved bodyaxis rolling motions at moderate (15- to 35-deg) angles of attack in both the Institute for Aerospace Research 2 X 3 m low-speed wind tunnel and the 7 X 10 ft Subsonic Aerodynamic Research Laboratory facility at Wright-Patter son Air Force Base. They included static, forced oscillation, and free-to-roll experiments with flow visualization. Multiple trim points (attractors) for body-axis rolling motions and other unusual dynamic behavior were observed. These data are examined in light of the nonlinear indicial response theory. The analysis confirms the existence of critical states with respect to roll angle. When these singularities are encountered in a dynamic situation, large and persistent transients are induced. Conventional means of representing the nonlinear forces and moments hi the aircraft equations of motion, notably the locally linear model, are shown to be inadequate for these cases. Finally, the impact of these findings on dynamic testing techniques is discussed.

75 citations

01 Mar 1985
TL;DR: In this article, a mathematical model of the aerodynamic contribution to the aircraft's equations of motion is amended to accommodate aerodynamic bifurcations such as, the onset of large-scale vortex shedding.
Abstract: Aerodynamic bifurcation is defined as the replacement of an unstable equilibrium flow by a new stable equilibrium flow at a critical value of a parameter A mathematical model of the aerodynamic contribution to the aircraft's equations of motion is amended to accommodate aerodynamic bifurcations Important bifurcations such as, the onset of large-scale vortex-shedding are defined The amended mathematical model is capable of incorporating various forms of aerodynamic responses, including those associated with dynamic stall of airfoils

74 citations