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This thesis work is part of a design process which aims to develop a four-seathybrid-electric aircraft at Smartflyer (Grenchen, Switzerland). In that scope,various mechanisms of the plane had to be developed, including the systemactuating the control surfaces. The objective of this thesis work is to designthe primary flight controls which will be implemented in the first prototypebuilt at Smartflyer.Firstly, the work investigates the calculation of the aerodynamic loads appliedto the control surfaces through the use of three different methods which areanalytical calculations, VLM analysis and CFD simulation. Then, the workconsists in defining the kinematic mechanisms of the flight control to handlethe deflection of the horizontal stabiliser, the ailerons and the rudder. Lastly,the calculation of the forces to which are submitted the components of theflight control is conducted. This step allows to determine the pilot controlforces and ensures to take into account the ergonomic aspect during the designphase. The results of this work highlight the limits of the different methodsused and serves as a basis for a future sizing work and detailed conception. / Detta uppsatsarbete är en del av en designprocess som syftar till att utvecklaett fyrsitsigt hybridelektriskt flygplan vid Smartflyer (Grenchen, Schweiz). Idetta omfång måste olika mekanismer i planet utvecklas, inklusive systemetsom manövrerar kontrollytorna. Syftet med detta uppsatsarbete är att utformade primära flygkontrollerna som kommer att implementeras i den första prototypensom byggdes på Smartflyer.För det första undersöker arbetet beräkningen av de aerodynamiska belastningarnasom appliceras på kontrollytorna genom användning av tre olika metodersom är analytiska beräkningar, VLM-analys och CFD-simulering. Därefter bestårarbetet i att definiera de kinematiska mekanismerna för flygkontrollen föratt hantera avböjningen av den horisontella stabilisatorn, kranarna och rodret.Slutligen genomförs beräkningen av de krafter till vilka komponenterna i flygkontrollenöverförs. Detta steg gör det möjligt att bestämma pilotstyrkrafternaoch säkerställer att man tar hänsyn till den ergonomiska aspekten under designfasen.Resultaten av detta arbete belyser gränserna för de olika metodersom används och tjänar som grund för ett framtida storleksarbete och detaljeraduppfattning.

The interaction of an aircraft's structure and the flight dynamics can degrade the performance of a controller designed only considering the rigid body flight dynamics. These concerns are greater for the next generation adaptive controls. These interactions lead to an increase in the tracking error, instabilities in the control parameters, and significant structural excitations. To improve the understanding of these issues the interactions have been examined using simulation as well as flight testing of a subscale aircraft. The scaling required for such a subscale aircraft has also been examined. For the simulation a coordinate system where the non-linear flight dynamics are orthogonal to the linear structural dynamics was defined. The orthogonality allows the use of separates models for the aerodynamics. For the non-linear flight dynamics, preexisting table lookups with extended vortex lattice are used to determine the aerodynamic forces. Strip theory is then used to determine the smaller, but still important, unsteady aerodynamic forces due to the flexible motion. Because the orientation of the engines is dependent on the structural deformations, the propulsive force is modeled as a non-conservative follower force. The simulation of the integrated dynamics is then used to examine the effects of the aircraft flexibility and resultant ASE interactions on the performance of adaptive controls. For the scaling, the complete similitude of a flexible aircraft was examined. However, this complete similitude is unfeasible for an actual model, so partial similitude is investigated using two approaches. First, the classical approximations of the flight dynamic modes are used to reduce the order of the coupled model, and consequently the number of scaling parameters required to maintain the physics of the system. The second approach uses sensitivity of the response to errors in the aircraft's nondimensional parameters. Both methods give a consistent set of nondimensional parameters which do not have significant influence on the aeroservoelastic interaction. These parameters do not need to be scaled, thus leading to a viable scaled model. A subscale vehicle has been designed which shows significant coupling between the flight dynamics and structural dynamics. This vehicle was used to validate the results of the scaling theory. Output error system identification was used to identify a model from the flight test data. This identified model provides the frequency of the short-period mode, and the effects of the Froude number on the flexibility. / Ph. D.

The nonlinear simulation model of an unmanned aerial vehicle (UAV) in MATLAB&reg / /Simulink&reg / environment is developed by taking into consideration all the possible major system components such as actuators, gravity, engine, atmosphere, wind-turbulence models, as well as the aerodynamics components in the 6 DOF equations of motion. Trim and linearization of the developed nonlinear model are accomplished and various related analyses are carried out. The model is validated by comparing with a similar UAV data in terms of open loop dynamic stability characteristics. Using two main approaches / namely, classical and optimal, linear controllers are designed. For the classical approach, Simulink Response Optimization (SRO) tool of MATLAB&reg / /Simulink&reg / is utilized, whereas for the optimal controller approach, linear quadratic (LQ) controller design method is implemented, again by the help of the tools put forth by MATLAB&reg / . The controllers are designed for control of roll, heading, coordinated turn, flight path, pitch, altitude, and airspeed, i.e., for the achievement of all low-level control functions. These linear controllers are integrated into the nonlinear model, by carrying out gain scheduling with respect to airspeed and altitude, controller input linearization regarding the perturbed states and control inputs, and anti integral wind-up scheme regarding the possible wind-up of the integrators in the controller structures. The responses of the nonlinear model controlled with the two controllers are compared based on the military flight control requirements. The advantages and disadvantages of these two frequently used controllers in industry are investigated and discussed. These results are to be evaluated by the designers themselves based on the design criteria of a project that is worked on.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The air-to-air refuelling of large aircraft presents challenges such as a long fuel transfer time, slow aircraft responses and a large distance between the aircraft CG and the receptacle position. This project addresses some of these issues by adding a control system to keep the receiver aircraft in the correct position relative to the tanker to enable fuel transfer. This project investigates different control strategies which are designed to control the A330-300 during refuelling at one trim condition. The controllers are based on a mathematical aircraft model which was derived from a simulation model received from Airbus. The first set of controllers uses the aircraft actuators directly. Controllers that are based on the CG dynamics and the receptacle dynamics are compared. Due to the large distance between the CG and the receptacle it was found to be essential to control the receptacle position, and not only the CG position. Also, a controller that is based on a model of the receptacle dynamics performs better. The second set of controllers uses the aircraft manual control laws as an inner loop controller. This set of controllers and the last direct actuator controller use the same axial controller that uses the engine thrust to control axial position. It was found that both the direct actuator controller and the manual control laws controller are able to keep the receptacle within the disconnect envelope in moderate turbulence. In both sets of controllers the axial controller fails to keep the receptacle reliably within the disconnect envelope in light turbulence. From the results it is concluded that both the direct actuator control and manual control laws can be used to successfully control the receptacle position in the normal and lateral positions as long as the receptacle kinematics are included in the control design. Using only the engine thrust for axial control is insufficient. Several recommendations are made to improve the axial control and also how these results can be used in future work. / AFRIKAANSE OPSOMMING: Die lug-tot-lug brandstof hervulling van groot vliegtuie het uitdagings soos ’n lang hervullingstyd, stadige vliegtuig dinamika en ’n groot afstand tussen die hervullingspoort en die vliegtuig massamiddelpunt. Hierdie projek spreek sommige van hierdie uitdagings aan deur ’n beheerstelsel by te voeg wat die vliegtuig in die korrekte posisie relatief tot die tenker hou vir brandstofoordrag om plaas te vind. Hierdie projek ondersoek verskillende beheerstrategieë wat ontwerp is om die A330- 300 te beheer by ’n enkele gestadigde toestand. Die beheerders is gebaseer op ’n wiskundige vliegtuigmodel wat vanaf ’n simulasiemodel afgelei is. Die simulasiemodel is vanaf Airbus verkry. Die eerste stel beheerders beheer direk die vliegtuig se beheeroppervlakke. Beheerders wat onderskeidelik die massamiddelpunt en die hervullingspoort beheer word vergelyk. Daar is gevind dat dit essensieel is om die hervullingspoort te beheer en nie slegs die massamiddelpunt nie, as gevolg van die groot afstand tussen hierdie twee punte. Die tweede stel beheerders gebruik die vliegtuig se eie beheerwette as ’n binnelusbeheerder en vorm self die buitelus. Albei stelle beheerders gebruik dieselfde aksiale beheerder wat enjin stukrag gebruik om die aksiale posisie te beheer. Daar is gevind dat beide stelle beheerders die hervullingspoort binne die ontkoppelingsbestek kan hou in die normale en laterale rigtings tydens matige turbulensie. In beide stelle beheerders is dit die aksiale beheerder wat faal om die hervullingspoort betroubaar in posisie te hou, selfs in ligte turbulensie. Vanaf die resultate word afgelei dat beide die direkte beheerder en die buitelusbeheerder gepas is om die laterale en normale posisiebeheer toe te pas mits die dinamika van die hervullingspoort in ag geneem word. Om slegs stukrag te gebruik vir aksiale beheer is nie voldoende nie, en verskeie voorstelle word gemaak om die aksiale beheer te verbeter in toekomstige navorsing.