Ride comfort in commercial aircraft during formation flight using conventional flight control

Trollip, Evert Frederick (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Global market forecasts and rapid air transport growth are making the aeronautical industry become aware of the necessity to develop high capacity long-range and fuel-effi cient aircraft while maintaining high levels of passenger comfort. With the large interest in automated formation flight and improvements in automated flight control, it is the aim of this research to evaluate passenger ride comfort in commercial aircraft during formation flight. The main objective of this thesis is to take into account the aircraft dynamics, atmospheric turbulence and the effect of a flight control system when evaluating the ride comfort of passengers. To achieve this objective, a detailed literature study into current and past projects was performed, focusing on formation flight, passenger comfort evaluation and improvements in passenger comfort with e fficient control systems design. Following the literature study, a theoretical Boeing B747 aircraft model was built and tested in MATLAB and Simulink. Subsequently, a conventional model of the fly-by-wire architecture used in modern transport aircraft was designed, implemented, and verified in simulation. To model the formation flight effects, the induced forces and moments on the follower aircraft due to the trailing vortices of the leader were derived in a previous study by Bizinos at the University of Cape Town. These induced loads, expressed as aerodynamic coffe cients, were used in conjunction with the conventional aerodynamic model to produce an extended aerodynamic model for formation flight. The conventional fly-by-wire control architecture used by modern transport aircraft has been extended for formation flight of two or more aircraft, with the focus on two aircraft in right echelon formation. A full non-linear simulation with realistic turbulence was produced to verify the working of the extended controllers and to ensure the follower maintains its path behind the leader aircraft. In formation flight, the passenger comfort is in influenced by disturbance loads due to the turbulence, as well as by compensatory control inputs produced by the autopilot controllers. The accelerations of passengers in a seated position were determined by considering the passenger's seated position with respect to the mass centre, and the forces and moments at and around the mass centre respectively. These accelerations are weighted according to their frequency to determine the comfort levels in accordance with the International Organisation for Standardisation (ISO 2631-1). Simulation results of the accelerations experienced at different locations in the trailing aircraft of a formation showed that very little difference in comfort can be expected between the different formation flight aircraft under the same flight conditions. It was concluded for both aircraft that a seating location at the front of the aircraft is more comfortable than one at the back of the aircraft. During light and moderate turbulence, the overall acceleration magnitudes remained within the not uncomfortable region suggested by the ISO 2631-1 standard. The percentage of ill passengers in isolated and formation flight is very low, making motion sickness incidence during formation flight almost no different to motion sickness during isolated flight.

AFRIKAANS OPSOMMING: Wêreldwye markvooruitskattings en snelle lugvervoergroei maak tans die lugvaartbedryf bewus van die noodsaaklikheid van ho ekapasiteit-, brandstofdoeltre ende langafstandvliegtuie wat ook ho e vlakke van passasiersgemak handhaaf. Gegewe die groot belangstelling in geoutomatiseerde formasievlug en die verbeteringe in geoutomatiseerde vlugbeheer, is dit die doel van hierdie navorsing om passasiersgemak in burgerlugvaart in formasievlug te evalueer. Die hoofdoelstelling van hierdie tesis is om die vliegtuigdinamiek, turbulensie en die e ek van 'n vlugbeheerstelsel in ag te neem wanneer die evaluering van passasiersgemak gedoen word. Om hierdie doelstelling te bereik, is 'n gedetailleerde literatuurstudie oor huidige en vorige projekte onderneem, met die fokus op formasievlug, die evaluering van passasiersgemak, en verbeteringe in passasiersgemak deur doeltre ende beheerstelselontwerp. N a die literatuurstudie is 'n teoretiese Boeing B747-vliegtuigmodel gebou en in MATLAB en Simulink getoets. Vervolgens is 'n konvensionele model van die elektroniese ( y-by-wire) argitektuur wat in moderne vervoervliegtuie gebruik word, ontwerp, ge mplementeer, en in simulasie geveri eer. Om die e ek van formasievlug te modelleer, is die ge nduseerde kragte en momente op die volgervliegtuig wat aan die volgwerwels van die leiervliegtuig te wyte is, afgelei in 'n vorige studie deur Bizinos aan die Universiteit van Kaapstad. Hierdie ge nduseerde kragte, uitgedruk as a erodinamiese ko e si ente, is tesame met die konvensionele a erodinamiese model gebruik om 'n uitgebreide a erodinamiese model vir formasievlug te skep. Die konvensionele elektroniese (fly-by-wire) beheerargitektuur wat moderne vervoervliegtuie gebruik, is uitgebrei vir formasievlugte met twee of meer vliegtuie, met die fokus op twee vliegtuie in regter-echelon formasie. 'n Volle nie-line^ere simulasie met realistiese turbulensie is geskep om die werking van die uitgebreide beheerders te veri eer, en te verseker dat die volgervliegtuig sy roete agter die leiervliegtuig volhou. In formasievlug word passasiersgemak be nvloed deur steuringslaste as gevolg van turbulensie, asook deur kompensatoriese beheerinsette wat deur die outoloodsbeheerders geproduseer word. Die versnellings van die passasiers in 'n sittende posisie is bepaal deur te kyk na die passasier se sittende posisie met betrekking tot onderskeidelik die massamiddelpunt en die kragte en momente by en rondom die massamiddelpunt. Hierdie versnellings is geweeg volgens hul frekwensie om die gemaksvlakke ingevolge die Internasionale Standaardeorganisasie (ISO 2631-1) te bepaal. Die simulasieresultate van die versnellings wat by verskillende liggings in die volgervliegtuig van 'n formasie ervaar is, het getoon dat weinig gemaksverskil verwag kan word tussen die verskillende formasievliegtuie onder dieselfde vlugtoestande. Die gevolgtrekking vir albei vliegtuie was dat 'n sitplekligging voor in die vliegtuig meer gemaklik is as een agter in die vliegtuig. Tydens ligte en matige turbulensie het die algehele versnellingsgroottes gebly binne die nie ongemaklik nie-gebied (not uncomfortable) soos voorgestel deur die ISO 2631-1-standaard. Die persentasie siek passasiers in ge soleerde en formasievlug is baie laag, wat beteken die voorkoms van bewegingsiekte (motion sickness) tydens formasievlug verskil byna glad nie van die voorkoms daarvan tydens ge soleerde vlug nie.

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