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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722136291 Category : Languages : en Pages : 100
Book Description
This document presents an approach for modeling and simulating landing gear systems. Specifically, a nonlinear model of an A-6 Intruder Main Gear is developed, simulated, and validated against static and dynamic test data. This model includes nonlinear effects such as a polytropic gas model, velocity squared damping, a geometry governed model for the discharge coefficients, stick-slip friction effects and a nonlinear tire spring and damping model. An Adams-Moulton predictor corrector was used to integrate the equations of motion until a discontinuity caused by a stick-slip friction model was reached, at which point, a Runga-Kutta routine integrated past the discontinuity and returned the problem solution back to the predictor corrector. Run times of this software are around 2 mins. per 1 sec. of simulation under dynamic circumstances. To validate the model, engineers at the Aircraft Landing Dynamics facilities at NASA Langley Research Center installed one A-6 main gear on a drop carriage and used a hydraulic shaker table to provide simulated runway inputs to the gear. Model parameters were tuned to produce excellent agreement for many cases. Daniels, James N. Langley Research Center...
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722136291 Category : Languages : en Pages : 100
Book Description
This document presents an approach for modeling and simulating landing gear systems. Specifically, a nonlinear model of an A-6 Intruder Main Gear is developed, simulated, and validated against static and dynamic test data. This model includes nonlinear effects such as a polytropic gas model, velocity squared damping, a geometry governed model for the discharge coefficients, stick-slip friction effects and a nonlinear tire spring and damping model. An Adams-Moulton predictor corrector was used to integrate the equations of motion until a discontinuity caused by a stick-slip friction model was reached, at which point, a Runga-Kutta routine integrated past the discontinuity and returned the problem solution back to the predictor corrector. Run times of this software are around 2 mins. per 1 sec. of simulation under dynamic circumstances. To validate the model, engineers at the Aircraft Landing Dynamics facilities at NASA Langley Research Center installed one A-6 main gear on a drop carriage and used a hydraulic shaker table to provide simulated runway inputs to the gear. Model parameters were tuned to produce excellent agreement for many cases. Daniels, James N. Langley Research Center...
Author: Jocelyn I. Pritchard Publisher: ISBN: Category : Aerodynamics Languages : en Pages : 22
Book Description
On of the problems facing the aircraft community is landing gear dynamics, especially shimmy and brake-induced vibration. Shimmy and brake-induced vibrations can lead to accidents due to excessive wear and shortened life of gear parts and contribute to pilot and passenger discomfort. To increase understanding of these problems, a literature survey was performed. The major focus is on work from the last ten years. Some older publications are included to understand the longevity of the problem and the background from earlier researchers. The literature survey includes analyses, testing, modeling, and simulation of aircraft landing gear; and experimental validation and characterization of shimmy and brake-induced vibration of aircraft landing gear. The paper presents an overview of the problem, background information, and a history of landing gear dynamics problems and solutions. Based on the survey an assessment and recommendations of the most critically needed enhancements to the state of the art will be presented. The status of Langley work contributing to this activity will be given.
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721181285 Category : Languages : en Pages : 34
Book Description
One of the problems facing the aircraft community is landing gear dynamics, especially shimmy and brake-induced vibration. Shimmy and brake-induced vibrations can lead to accidents due to excessive wear and shortened life of gear parts and contribute to pilot and passenger discomfort. To increase understanding of these problems, a literature survey was performed. The major focus is on work from the last ten years. Some older publications are included to understand the longevity of the problem and the background from earlier researchers. The literature survey includes analyses, testing, modeling, and simulation of aircraft landing gear; and experimental validation and characterization of shimmy and brake-induced vibration of aircraft landing gear. The paper presents an overview of the problem, background information, and a history of landing gear dynamics problems and solutions. Based on the survey an assessment and recommendations of the most critically needed enhancements to the state of the art will be presented. The status of Langley work contributing to this activity will be given. Pritchard, Jocelyn I. Langley Research Center NASA/TM-1999-209143, NAS 1.15:209143, ARL-TR-1976, L-17840
Author: Lucas G. Horta Publisher: ISBN: Category : Airplanes Languages : en Pages : 36
Book Description
Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground-induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads by using actively controlled landing gear. A facility has been developed to test various active landing gear control concepts and their performance. The facility uses a Navy A6 Intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented, including modifications to actuate the gear externally, and test data are used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.
Author: Kamran Behdinan Publisher: John Wiley & Sons ISBN: 1119756723 Category : Technology & Engineering Languages : en Pages : 256
Book Description
Offers a review of the newest methodologies for the characterization and modelling of lightweight materials and structures Advances in Multifunctional Lightweight Structures offers a text that provides and in-depth analyses of the thermal, electrical and mechanical responses of multi-functional lightweight structures. The authors, noted experts on the topic, address the most recent and innovative methodologies for the characterization and modelling of lightweight materials and discuss various shell and plate theories. They present multifunctional materials and structures and offer detailed descriptions of the complex modelling of these structures. The text is divided into three sections that demonstrate a keen understanding and awareness for multi-functional lightweight structures by taking a unique approach. The authors explore multi-disciplinary modelling and characterization alongside benchmark problems and applications, topics that are rarely approached in this field. This important book: • Offers an analyses of the thermal, electrical and mechanical responses of multi-functional lightweight structures • Covers innovative methodologies for the characterization and modelling of lightweight materials and structures • Presents a characterization of a wide variety of novel materials • Considers multifunctional novel structures with potential applications in different high-tech industries • Includes efficient and highly accurate methodologies Written for professionals, engineers and researchers in industrial and other specialized research institutions, Advances in Multifunctional Lightweight Structures offers a much needed text to the design practices of existing engineering building services and how these methods combine with recent developments.
Author: Publisher: ISBN: Category : Aircraft Languages : en Pages : 86
Book Description
The ability to accurately predict the dynamic response of an aircraft while it is operating in the taxi mode depends, in part on the correct modeling of the dynamic characteristics of the landing gear system. Traditionally, landing gear have been designed to absorb landing impact ('shock absorber') and their characteristics during periodic, oscillatory response ('spring') have been considered as secondary. With the increased emphasis on the rough or damaged field taxi operation, there is a requirement to determine the best methods for modeling the gear system. This report documents a brief review of the state of the art of gear modeling. A study was then conducted to evaluate important model parameters, using a simple cantilevered gear computer simulation. Also included is the development of a technique for the experimental determination of important gear system parameters. (Author).
Author: SanoopKumar Ambalaparambil Publisher: ISBN: Category : Airplanes Languages : en Pages : 450
Book Description
"The focus of this work is the development of a Multi-degree Of Freedom (MOF) model for simulation and control of the landing performances of the SAE Heavy Lift Airplane model built by the Aerodynamics design team of RIT. From dynamic considerations, the landing gear performance has two areas of interest: a) behavior during touchdown impact, and b) response to excitation induced by track roughness during taxi, take-off and later part of the landing runs. As the problem at hand is highly nonlinear and complex, initially a simplified 1-dof model of the same aircraft is derived and analyzed using Lagrange's equations and energy methods. After understanding the basic dynamics of the system, a more complex 3-dof model is derived considering the dynamics of the wheels of the landing gear. Analyses with and without the runway profile are carried out to study the effects of the input signals on the derived model. In order to achieve a controlled landing behavior of the aircraft, a linear damper or shock absorber is incorporated into the analysis and simulation, even though it is not available in the original prototype. The nonlinear models are linearized in Simulink and control system designs are performed on the linearized models using Root Locus techniques, Pole Placement methods, LQR approach, and Error Space approach. The designed controllers are then applied on the original nonlinear 3-dof model of the landing gear and a study of the effects of changing landing gear parameters is performed. Open loop and Closed loop simulations are carried out to come up with an effective controller type, which will ensure optimum landing performance in a normal landing situation."--Abstract.
Author: National Aeronautics and Space Administration (NASA)
Author: James Nathan Daniels
Author: National Aeronautics and Space Administration (NASA)
Author: Jocelyn I. Pritchard
Author: National Aeronautics and Space Administration (NASA)
Author: Lucas G. Horta
Author: Kamran Behdinan
Author: 
Author: Daniel Armstrong
Author: SanoopKumar Ambalaparambil
Author: