Rotor failure compensation in a biplane quadrotor based on virtual deflection

A biplane quadrotor is a hybrid type of UAV that has wide applications such as payload pickup and delivery, surveillance, etc. This simulation study mainly focuses on handling the total rotor failure, and for that, we propose a control architecture that does not only handle rotor failure but is also able to navigate the biplane quadrotor to a safe place for landing. In this structure, after the detection of total rotor failure, the biplane quadrotor will imitate reallocating control signals and then perform the transition maneuver and switch to the fixed-wing mode; control signals are also reallocated. A synthetic jet actuator (SJA) is used as the redundancy that generates the desired virtual deflection to control the pitch angle, while other states are taken care of by the three rotors. The SJA has parametric nonlinearity, and to handle it, an inverse adaptive compensation scheme is applied and a closed-loop stability analysis is performed based on the Lyapunov method for the pitch subsystem. The effectiveness of the proposed control structure is validated using numerical simulation carried out in the MATLAB Simulink.Web of Science67art. no. 17

Effectiveness of synthetic jet actuators for separation control on an airfoil

The aerodynamic performance of an airfoil could be improved by controlling flow separation using active flow control techniques. In this study, a synthetic jet actuator (SJA) based on piezoelectric diaphragm has been developed. The selection of the SJA was due to their advantages in being lightweight, no external air supply required, simple system assembly, fast time response, low power consumption, easy installation, low cost and relatively small in size. Basically, the performance of the SJA depends on the specification and configuration of jet orifice, cavity, and oscillating membrane. The parameters studied include waveform signal, frequency, voltage, cavity and orifice physical characteristics. Final design and geometry of the SJA were determined based on these parameters. The SJA design with the best performance has been developed to generate sufficient air jet velocity to control flow separation. The experimental results measured by a hot-wire anemometer show that the maximum jet velocity obtained by the SJA with circular and slot orifice were 41.71 m/s and 35.3 m/s at an applied frequency of 900 Hz and 1570 Hz respectively. Next, the selected SJA was embedded into the wing with NACA 0015 airfoil and placed at 12.5% chord from the leading edge. Wind tunnel testing was conducted for stationary and oscillating airfoil conditions, with and without the SJA. The unsteady aerodynamic loads were calculated from the surface pressure measurements of 30 ports along the wing chord for both upper and lower surfaces. The airfoil was tested at various angles of attack at a free-stream velocity of up to 35 m/s corresponding to a Reynolds number of 1.006 x 106. Specifically for an oscillating airfoil, the reduced frequency, k, was varied from 0.02 to 0.18. The results of an airfoil with SJA showed that the CLmax and stall angle increased up to 13.94% and 29% respectively. Based on the results obtained, the SJA has an excellent capability to control the flow separation with delaying the stall angle, increasing the maximum lift, reducing the drag and delaying the intense nose down pitching moment

The Edge supersonic transport

As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars)

Characterizing Wake Roll-Up and Vortex Structure for Delta Wing Configuations Featuring Flow Control Devices at Low Reynolds Number

Various configurations of a cropped delta wing featuring a NACA 0012 wing-section were evaluated experimentally at a Reynolds number of 5.0 x 105 in the Air Force Institute of Technology Low-Speed Wind Tunnel facility. The effects of active flow control (AFC) and passive boundary-layer fences (BLF) were shown to improve high angle of attack delta wing performance. The AFC BLFs were shown to replicate the performance enhancements found in passive BLFs without incurring a drag penalty. An experimental characterization of the wake region is presented to compare the wake roll-up and leading edge vortices for these baseline, passive BLF, and AFC BLF delta wing configurations. Using a tuft mesh and a constant temperature anemometry triple wire probe, the wake was characterized at several discrete planes of interest aft of the trailing edge. This wake data was used to elucidate causes for AFC BLF configuration increasing the maximum lift coefficient by 60.3%. The present study shows this aerodynamic improvement is largely attributed to: 1) strengthening the leading edge vortex (LEV), which delays vortex breakdown, and 2) truncating spanwise flow

CHARACTERIZATION AND FLOW PHYSICS OF PLASMA SYNTHETIC JET ACTUATORS

Plasma synthetic jet actuators are investigated experimentally, in which the geometrical design of single dielectric barrier discharge (SDBD) plasma actuators is modified to produce zero-mass flux jets similar to those created by mechanical devices. The SDBD plasma actuator consists of two rectangular electrodes oriented asymmetrically and separated by a layer of dielectric material. Under an input of high voltage, high frequency AC or pulsed DC, a region of plasma is created in the interfacial air gap on account of electrical breakdown of the ambient air. A coupling between the electric field in the plasma and the neutral air near the actuator is introduced, such that the latter experiences a net force which results in a horizontal wall jet. This effect of the actuator has been demonstrated to be useful in mitigating boundary layer separation in aerodynamic flows. To increase the impact that a plasma actuator may have on the flow field, this research investigates the development and characterization of a novel flow control device, the plasma synthetic jet actuator, which tailors the residual air in the form of a vertical jet resembling conventional continuous and synthetic jets. This jet can be either three dimensional using annular electrode arrays, or nearly two dimensional using two rectangular strip exposed electrodes and one embedded electrode. Detailed measurements on the isolated plasma synthetic jet reveal that pulsed operation of the actuator results in the formation of multiple counterrotating vortical structures in the flow field. The output jet velocity and momentum are found to be higher for unsteady pulsing as compared to steady operation. In the case of flow over a flat plate, the actuator is observed to create a localized interaction region within which the baseline flow direction and boundary layer characteristics are modified. The efficiency of the actuator in coupling momentum to the neutral air is found to be related to the plasma morphology, pulsing frequency, actuator dimension, and input power. An analytical scaling model is proposed to describe the effects of varying the above variables on the output jet characteristics and actuator efficiency, and the experimental data is used for model validation

Proposal and preliminary design for a high speed civil transport aircraft. Swift: A high speed civil transport for the year 2000

To meet the needs of the growing passenger traffic market in light of an aging subsonic fleet, a new breed of aircraft must be developed. The Swift is an aircraft that will economically meet these needs by the year 2000. Swift is a 246 passenger, Mach 2.5, luxury airliner. It has been designed to provide the benefit of comfortable, high speed transportation in a safe manner with minimal environmental impact. This report will discuss the features of the Swift aircraft and establish a solid, foundation for this supersonic transport of tomorrow

Recent Progress in Some Aircraft Technologies

The book describes the recent progress in some engine technologies and active flow control and morphing technologies and in topics related to aeroacoustics and aircraft controllers. Both the researchers and students should find the material useful in their work

Lentokoulutussimulaattoreiden validoidun lentoarvoalueen arviointi epätavallisten lentotilojen koulutusta varten

Loss of control in-flight has been the most significant contributor fatal accidents in commercial air transport over the last decade. The mitigation of this accident type has been raised as one of the top safety priorities in commercial civil aviation. As a reaction to the circumstances, the European Aviation Safety Agency and the Federal Aviation Administration of the United States have issued new provisions in effort to ensure that flight training provides pilots with the necessary knowledge and skill-set required to detect, avoid and, when needed, recover from aeroplane upset situations. Consequently, the qualification requirements for flight training simulators have been adapted to match this renewed type of training. Until recently, previously qualified simulators have not been required to demonstrate realistic fidelity outside of the normal training envelope. The objectives of this master’s thesis are to examine the status of the current and foreseeable regulatory framework related to upset prevention and recovery training, and to study how previously qualified simulators may be demonstrated compliant with the novel provisions. This thesis is conducted by means of a literature study and two case studies. In the first case study an aerodynamic data package of a large transport aeroplane is examined in order to assess the ranges of aerodynamic data typically available for a simulator flight model, and to underline the essential aerodynamic stability derivatives that are required to evaluate the fidelity of a simulator flight model. The second case study focuses on determining a validated training envelope for a previously qualified simulator, currently in use in flight training organisation environment. The range of the aerodynamic data encompassed within the simulator flight model was uncovered by examining the source code and software documentation of the simulator. Finally, a flight validated envelope was constituted by means of experimental testing and matching the response of the simulator with available flight test data. The problematics of this case study correspond to the typical challenging case in the industry, where support from the manufacturer is no longer available for an older device.Lennonaikainen hallinnanmenetys on aiheuttanut kaupallisessa ilmakuljetuksessa enemmän kuolonuhreja kuin mikään muu onnettomuustyyppi kuluneen vuosikymmenen aikana. Kyseisen onnettomuustyypin ennaltaehkäisy on noussut yhdeksi tärkeimmistä lentoturvallisuuden kehityskohteista. Euroopan lentoturvallisuusvirasto EASA ja Yhdysvaltain ilmailuhallinto FAA ovat reagoineet tilanteeseen uusilla vaatimuksilla, tarkoituksenaan varmistaa lentokoulutuksen antavan lentäjille valmiuksia välttää epätavallisia lentotiloja ja tarvittaessa suorittaa oikaisu. Tässä yhteydessä myös lentokoulutuksessa käytettäviä simulaattoreita koskeviin vaatimuksiin on tehty merkittäviä muutoksia. Aikaisemmin hyväksytyiltä simulaattoreilta ei ole vaadittu samaa realismin tasoa lentokoulutuksessa tavallisesti saavutetun lentoarvoalueen ulkopuolella. Tämän diplomityön tavoitteena on selvittää epätavallisten lentotilojen koulutusta koskevien viranomaisvaatimusten nykytila ja lähitulevaisuuden näkymät, sekä tutkia kuinka vaatimustenmukaisuus voidaan osoittaa jo koulutuskäyttöön hyväksyttyjen simulaattoreiden kohdalla – tarkoittaen käytännössä simulaattorin lentomallin validointia oikeasta lentokoneesta mitattua koelentodataa vasten. Diplomityö koostuu kirjallisuusselvityksestä, sekä kahdesta tapaustutkimuksesta. Ensimmäinen tapaustutkimus toteutettiin aineistoanalyysinä julkisesti saatavilla olevasta liikennelentokoneen koelentodatapaketista, tavoitteena tutkia miltä lentoarvoalueelta on tyypillisesti käytettävissä aerodynaamista dataa simulaattorin mallinnusta varten, sekä tutkia mitkä aerodynaamiset stabiliteettiderivaatat ovat oleellisimpia simulaattorin lentomallin vaatimustenmukaisuuden arvioinnin kannalta. Toisessa tapaustutkimuksessa määritettiin lentokoulutusorganisaatioympäristössä käytössä olevalle simulaattorille epätavallisten lentotilojen koulutuksessa vaadittu validoitu lentoarvoalue. Tutkimuksessa selvitettiin simulaattorin lähdekoodista ja ohjelmistokuvauksista lentomallin sisältämän aerodynaamisen datan kattama arvoalue. Validoitu lentoarvoalue selvitettiin kokeellisella testauksella, verraten simulaattorin vastetta saatavilla olevaan koelentodataan. Tapaustutkimuksen asetelma vastaa tyypillistä hankalaa tapausta, jossa valmistajan tuotetukea ei ole enää saatavilla

Unmanned Aerial Vehicle for Flow Control Experiments with Dielectric Barrier Discharge Plasma Actuators

Dielectric Barrier Discharge (DBD) plasma actuators are a relatively novel type of actuators for active flow control. They offer several benefits, such as fast reaction times due to the absence of mechanical parts. On the other hand there are several difficulties which must be overcome before they reach a stage of maturity suitable for application on aircraft. In the present study the design, construction and commissioning of an Unmanned Aerial Vehicle (UAV) for flow control experiments with plasma actuators under realistic flight conditions is presented. The UAV has a wingspan of 2.38 m and a flight mass of approximately 10 kg. It is equipped with a flight control system to autonomously conduct the experiments and record measurement data. The fault-free operation of all systems, despite electromagnetic emissions from the high-voltage system of the actuators, and the suitability of the UAV as a flight-test platform have been demonstrated. Two sections of the modular wing are used for flow control, different airfoil and actuator configurations can thus be interchanged. The attainable Reynolds numbers are in the range of 300, 000 to 600, 000. Validation of the entire system with several configurations has been performed in the wind tunnel prior to free-flight experiments