• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 2
  • 1
  • 1
  • Tagged with
  • 12
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Design of a manual roll control for a trainer aircraft

Masefield, O. L. P. January 1990 (has links)
Turbo-prop trainer aircraft are designed to offer a cost effective alternative to military jet training aircraft. As a design objective of such aircraft, the Military Specifications of handling qualities applicable to jet trainer aircraft should be satisfied. However, in line with the philosophy of low purchase and maintenance costs, the added complexity of a hydraulic power boost system for the control surfaces cannot be accepted. The objective of this work was to optimise the roll control system so as to achieve an optimum of ergonomic design combined with the performance goals of the military specifications, using purely aerodynamic means of balance. Relevant British and American civilian and military specifications and simulator studies have been reviewed to select the detailed design objectives of the study. The American Mil. Specs. were selected as a baseline, with modifications derived from the results of simulator experiments. A Baseline Aircraft was selected on which to apply the optimisation. The highest performance turbo-prop trainer of the time was selected. A mathematical model of the roll response was derived for the extrapolation of flight test data and to allow an evaluation and optimisation of the critical aileron parameters. A description of the model and comparison to flight test results is given in the text. Literature was searched to examine the availability of information for the aerodynamicist to conduct such an optimisation. The results were disappointing, showing that very little work had been conducted on aileron design since the late 1940's and that the work of that time was not entirely relevant to today's requirements. Because the literature search was not conclusive, further flight tests had to be conducted on the Baseline Aircraft to investigate different forms of aerodynamic balance. The performance of the ailerons and some of the problems encountered in their usage are reported in this thesis and forms a data bank from which to conduct the optimisation. Finally, a selection process is conducted to size the aileron to satisfy the performance goals and to select the best aerodynamic balance to achieve the ergonomic goals. The achieved performance is summarised and compared with the original design goals. It is concluded that the optimised aileron is capable of achieving the design goals over the major portion of the design envelope. The design optimisation process is not limited to turbo-prop aircraft but can be applied to any high performance aircraft with reversible controls.

Enhancement of roll maneuverability using post-reversal design

Li, Wei-En. January 2009 (has links)
Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Hodges, Dewey; Committee Member: Bauchau, Olivier; Committee Member: Goldsman, David; Committee Member: Prasad, J.V.R.; Committee Member: Smith, Marilyn. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Nonlinear aeroelastic effects in damaged composite aileron-wing structures

Douxchamps, Benoit 12 1900 (has links)
No description available.

Modelling and testing smart aileron servo tabs : developing simulation tools for smart materials

Msomi, Velaphi January 2015 (has links)
Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015. / This dissertation addresses the development and the testing of a simulation tool to be used to predict the behaviour of smart material/structures. Along with the development of the simulation tool, a new form of the model describing the behaviour of shape-memory alloy was developed and implemented. The proposed model was developed based on the existing cosine model, conventionally used in literature, but it uses hyperbolic tangent functions. The hyperbolic tangent function was chosen so as to allow the simulation of any range of temperatures. Experiments were performed to obtain the parameters to be used in the simulation and to validate the numerical results. Two different simulations were performed: a one dimensional FEA analysis with a two dimensional orientation (NiTi SMA wire simulation) and a three dimensional FEA analysis (NiTi SMA plate) [Msomi and Oliver, 2015]. Alongside the FEA analysis, two experiments were performed with the purpose of obtaining the material parameters to be used in FEA analysis and to compare the FEA results to the experimental results. / Airbus Company

Enhancement of roll maneuverability using post-reversal design

Li, Wei-En 22 June 2009 (has links)
This dissertation consists of three main parts. The first part is to discuss aileron reversal problem for a typical section with linear aerodynamic and structural analysis. The result gives some insight and ideas for this aeroelastic problem. Although the aileron in its post-reversal state will work the opposite of its design, this type of phenomenon as a design root should not be ruled out on these grounds alone, as current active flight-control systems can compensate for this. Moreover, one can get considerably more (negative) lift for positive flap angle in this unusual regime than positive lift for positive flap angle in the more conventional setting. This may have important implications for development of highly maneuverable aircraft. The second part is to involve the nonlinear aerodynamic and structural analyses into the aileron reversal problem. Two models, a uniform cantilevered lifting surface and a rolling aircraft with rectangular wings, are investigated here. Both models have trailing-edge control surfaces attached to the main wings. A configuration that reverses at a relatively low dynamic pressure and flies with the enhanced controls at a higher level of effectiveness is demonstrated. To evaluate how reliable for the data from XFOIL, the data for the wing-aileron system from advanced CFD codes and experiment are used to compare with that from XFOIL. To enhance rolling maneuverability for an aircraft, the third part is to search for the optimal configuration during the post-reversal regime from a design point of view. Aspect ratio, hinge location, airfoil dimension, inner structure of wing section, composite skin, aeroelastic tailoring, and airfoil selection are investigated for cantilevered wing and rolling aircraft models, respectively. Based on these parametric structural designs as well as the aerodynamic characteristics of different airfoils, recommendations are given to expand AAW flight program.

Control surfaces in confined spaces : the optimisation of trailing edge tabs to reduce control surface hinge moments

Jaquet, Christopher Denis 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This thesis describes the first project relating to the Control Surfaces in Confined Spaces (CoSICS) project at Stellenbosch University. The aim of CoSICS project is to reduce the size of control surface actuators, and this thesis considers the aileron system of commercial aircraft such as the Airbus A320 and A330. Specifically the project aims to reduce the aileron hinge moment, as this will result in smaller actuators. Possible methods are discussed where aerodynamic forces are used to reduce the aileron hinge moment through the use of a wing-aileron-tab configuration. In order to examine the use of the configuration, first order aerodynamic modelling is performed using two-dimensional thin-aerofoil theory, which is also extended to a basic three-dimensional approximation. To determine the maximum reduction in hinge moment several optimisations are performed where only the tab chord length is varied, both tab and aileron chord lengths are varied, and finally the tab chord length and aileron span are varied. The optimisation methods used, namely the gradient-based sequential quadratic programming (SQP) and a real-encoded genetic algorithm (REGA) are discussed in detail and include general implementations which are then applied to the problem. The optimisations performed are dual-layered where optimal deflection angles are determined as well as the optimal geometry. The results of the optimisation are tested using a roll manoeuvre in a specially developed Simulink simulation environment for this purpose. The study produces results where new hinge moment values are an order of magnitude smaller than those of the old configuration, while maintaining suitable lift and rolling moment coefficients. The optimisation and simulation infrastructure developed in this thesis provides a platform for higher-fidelity models and components being developed in future work to provide higher fidelity results. / AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die eerste projek in die Control Surfaces in Confined Spaces-projek1 (CoSICS-projek) uitgevoer by die Universiteit Stellenbosch. Die doel van die COSICs-projek is om die grootte van beheervlak aktueerders te minimeer en hierdie tesis handel oor die aileron stelsel van kommersiële vliegtuie soos die Airbus A320 en A330. Die doel van hierdie tesisis om die skarnier draaimoment van die aileron te minimeer deur aërodinamiese kragte in te span in ’n vlerk-aileron-hulpvlak konfigurasie. Eerste-orde aërodinamiese modelle is afgelei met behulp van twee-dimensionele dunvlerkteorie en is gebruik om die konfigurasie te analiseer. ’n Eerste orde drie-dimensionele benadering is ook ontwikkel. Om die maksimum vermindering in die skarnier draaimoment te bepaal, is verskeie optimerings uitgevoer waar eers die hulpvlak se koordlengte gevarieer word, daarna beide die aileron en hulp-vlak se koordlengtes en laastens die hulp-vlak se koordlengte en wydte. Die twee optimerings metodes wat gebruik is, nl. ’n sekwensiële kwadratiese programmerings (SKP) tegniek, en ’n reële getal-geënkodeerde genetiese algoritme (RGGA), word bespreek en ontwikkel voor hulle toegepas word op die probleem. Twee-vlak optimerings word uitgevoer waar beide die optimale defleksiehoeke en die optimale geometrie bepaal word. Die resultate van die optimering word daarna getoets deur middel van ’n rol maneuver wat uitgevoer word in ’n Simulink simulasie omgewing wat daarvoor geskep is. Hierdie studie lei tot goeie resultate met skarnier draaimoment waardes ’n ordegrootte kleiner as dié van die vorige stelsel, terwyl goeie waardes van rol-moment en verheffingskrag koëffisiënte behou word. Die optimering en simulasie infrastruktuur wat hier ontwikkel word verskaf ’n platform vir meer akkurate modelle en komponente wat ontwikkel word in toekomstige projekte om meer akkurate resultate te lewer.

Wind Tunnel and Flight Testing of Active Flow Control on a UAV

Babbar, Yogesh 2010 May 1900 (has links)
Active flow control has been extensively explored in wind tunnel studies but successful in-flight implementation of an active flow control technology still remains a challenge. This thesis presents implementation of active flow control technology onboard a 33% scale Extra 330S ARF aircraft, wind tunnel studies and flight testing of fluidic actuators. The design and construction of the pulsed blowing system for stall suppression (LE actuator) and continuous blowing system for roll control (TE actuator) and pitch control have been presented. Full scale wind tunnel testing in 7̕ X 10 Oran W. Nicks low speed wind tunnel shows that the TE actuators are about 50% effective as the conventional ailerons. The LE actuator is found to be capable of suppressing stall from 12° to about 22°. Comparison of characteristics of Active elevator and conventional elevator in 3' X 4' low speed wind tunnel show that, the active elevator is as effective as of conventional elevator deflected at 5°. Flight tests show that TE actuators are able to control the aircraft in flight in banked turns. The measured roll rates in-flight support the wind tunnel test findings.

Modelagem e simulação de um sistema de comando de aileron.

Cássio Henrique Mendonça 26 March 2004 (has links)
O estudo de sistemas mecânicos e hidráulicos foi desenvolvido para a execução da modelagem dinâmica de um servo-atuador hidromecânico de comando da superfície de controle de rolagem, aileron, da aeronave CJ1 desenvolvida durante a fase prática do Mestrado Profissionalizante da EMBRAER. Este trabalho aborda a modelagem e simulação de todos componentes internos do servo-atuador hidromecânico. Com esta modelagem podem-se fazer verificações de comportamento normal e comportamento anormal após a inserção de falhas nos componentes. Para tanto, fez-se uso de software compatível com os padrões EMBRAER, os quais são MatLab e Simulink. As simulações são quase todas não lineares e foram feitas utilizando tanto linguagem de programação quanto diagrama de blocos.

Control of surfaces in confined spaces : Tab-aileron control system development

Rupert, Francois Johannes 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: This thesis forms part of the Control Surfaces in Confined Spaces (CoSICS) project conducted at Stellenbosch University. The aim of this project is reduction of control surface actuator footprints on the existing wing structures of commercial airliners such as the Airbus A320 and A330. This is achieved by reducing control surface hinge moments through the application of trailing edge tabs. This results in smaller actuator requirements. The first tier of the project focussed on the geometric optimisation of the tab applied to an aileron. This thesis focusses on the development of dynamic control of the aileron through either tab-only or concurrent tab and aileron actuation. In the effort to develop dynamic control, a fully coupled generalised dynamic model of the tab and aileron is derived and presented. Through linearisation of this model, linear controllers are developed. Two distinctly different controllers are presented; the first controller makes use of classical methods for control of the tab-only actuated aileron and the second controller makes use of modern control techniques such as full state feedback to facilitate controlled concurrent tab and aileron actuation. Each proposed controller is evaluated in terms of dynamic performance, robustness, disturbance rejection and noise immunity. Based on the controller development, a summary of dynamic actuator requirements is given. Practical verification of the model and the controller performance is then undertaken. The development of the necessary hardware and software is also presented. The concept of aileron control through tab-only actuation and concurrent tab and aileron actuation is then validated. Conclusion are then drawn about the accuracy of the theoretical model and the practical performance of the controllers. The thesis is concluded with recommendations for future work to increase the fidelity of the model. Important aspects about the practical implementation of the concept on commercial jetliners are also summarised. / AFRIKAANSE OPSOMMING: Hierdie tesis is deel van die Control Surfaces in Confined Spaces1 projek by Stellenbosch Universiteit. Die doel van hierdie projek behels die verkleining van die aktueerder spasie en ondersteunings struktuur vereistes, op die bestaande vlerk struktuur van kommersiële vliegtuie soos die Airbus A320 en Airbus A330. Dit is bereik deur die vermindering van die beheeroppervlak skarnier se draaimoment met behulp van aerodinamiese hulpvlakke. Kleiner aktueerders word dus benodig. Die eerste stadium van die projek fokus op die geometriese optimisering van die hulpvlak op ’n aileron. Hierdie tesis fokus op die ontwikkeling van dinamiese beheer van die aileron deur middel van hulpvlak aktueering alleenlik of met die gelyktydige aktueering van die hulpvlak en aileron. In die proses van onwikkeling is ’n volgekoppelde veralgemeende dinamiese model van die hulpvlak en aileron afgelei en voorgelê. Deur middel van linearisasie van die model is linieêre beheerders ontwikkel. Tans is twee verskillende beheerders ontwikkel. Die eerste beheerder is gebaseer op die klassieke metodes en maak staat op die aktueering van die hulpvlak alleenlik. Die tweede beheerder maak gebruik van moderne beheer tegnieke soos vol toestand terugvoer om gelyktydige hulpvlak en aileron aktueering te realiseer. Die beheerders is elk geëvalueer in terme van dinamiese gedrag, robuustheid, versteurings verwerping en ruis verwerping. Die beheerstelsel ontwikkeling lei tot ’n opsomming van die dinamiese aktueerder vereistes. Dit word gevolg deur praktiese verifikasie van die model en die beheerstelsel gedrag. ’n Opsomming van die ontwikkeling van nodige hardeware en sagteware word voorgelê. In hierdie proses is die konsep van beide hulpvlak alleenlike aktueering en gelyktydige hulpvlak en aileron aktueering bewys. Gevolgtrekkings word gemaak oor die akkuraatheid van die model en die praktiese gedrag van die beheerders. Die tesis word afgerond met voorstelle vir toekomstige werk wat die model se betroubaarheid kan verbeter. Verder word belangrike punte oor die praktiese aspekte van konsep implementering op kommersiële vliegtuie ook uitgelig.

Hydraulic actuator failure prognostics.

João Pedro Pinheiro Malère 13 April 2007 (has links)
This work presents an application of failure prognosis in the system command actuator of a commercial aircraft. An efficient failure prognostic algorithm provides a reduction in the number of unscheduled events and consequently generates a significant reduction in the maintenance costs. Although this is a simulation-based work, it presents a pre validation with bench tests data. The method starts by computational mathematical modeling of the system and this further validation by laboratory results. The sensitivity study of the variables is necessary in order to understand which parameters affect the system. The estimation of a confidence interval to determine the nominal behavior failure allows detection and isolation. Parity state techniques will be used for the residue signals design which will be the of the degradation measurement. A simulation of the failure behavior over the time to forecast when the system will reach a determined threshold is also presented.

Page generated in 0.0889 seconds