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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 101 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 261)
Advances in Space Research     Full-text available via subscription   (Followers: 306)
Aeronautica     Open Access   (Followers: 20)
Aerospace     Open Access   (Followers: 37)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 179)
Aerospace Science and Technology     Hybrid Journal   (Followers: 282)
AIAA Journal     Full-text available via subscription   (Followers: 683)
Air Force Magazine     Full-text available via subscription   (Followers: 7)
Air Medical Journal     Hybrid Journal   (Followers: 2)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 132)
American Journal of Space Science     Open Access   (Followers: 100)
Annual of Navigation     Open Access   (Followers: 19)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 16)
ASTRA Proceedings     Open Access  
Aviation     Hybrid Journal   (Followers: 9)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 13)
Aviation Week     Full-text available via subscription   (Followers: 207)
Aviation, Space, and Environmental Medicine     Full-text available via subscription   (Followers: 7)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 25)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 26)
Chinese Journal of Aeronautics     Open Access   (Followers: 14)
Ciencia y Poder Aéreo     Open Access  
Control Systems     Hybrid Journal   (Followers: 86)
Cosmic Research     Hybrid Journal   (Followers: 2)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 6)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 19)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 2)
Fatigue of Aircraft Structures     Open Access   (Followers: 10)
Frontiers in Aerospace Engineering     Open Access   (Followers: 10)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 8)
Giroskopiya i Navigatsiya     Open Access  
Gyroscopy and Navigation     Hybrid Journal   (Followers: 179)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 121)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 21)
International Journal of Aeroacoustics     Full-text available via subscription   (Followers: 27)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 17)
International Journal of Aerospace Engineering     Open Access   (Followers: 63)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 17)
International Journal of Aerospace Sciences     Open Access   (Followers: 21)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 2)
International Journal of Aviation Management     Hybrid Journal   (Followers: 5)
International Journal of Aviation Psychology     Hybrid Journal   (Followers: 11)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 4)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 7)
International Journal of Flow Control     Full-text available via subscription   (Followers: 5)
International Journal of Hypersonics     Full-text available via subscription   (Followers: 4)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 7)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 6)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 4)
International Journal of Space Structures     Full-text available via subscription   (Followers: 6)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 5)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 1)
International Journal of Turbo & Jet-Engines     Hybrid Journal   (Followers: 3)
Journal of Aeronautical Materials     Open Access   (Followers: 2)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 9)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 54)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 8)
Journal of Aerospace Information Systems     Full-text available via subscription   (Followers: 1)
Journal of Aerospace Technology and Management     Open Access   (Followers: 2)
Journal of Aircraft     Full-text available via subscription   (Followers: 183)
Journal of Airline and Airport Management     Open Access   (Followers: 7)
Journal of Astrobiology & Outreach     Open Access   (Followers: 1)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 9)
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 110)
Journal of Konbin     Open Access  
Journal of Navigation     Hybrid Journal   (Followers: 173)
Journal of Propulsion and Power     Full-text available via subscription   (Followers: 334)
Journal of Space Weather and Space Climate     Open Access   (Followers: 19)
Journal of Spacecraft and Rockets     Full-text available via subscription   (Followers: 486)
Journal of Spatial Science     Hybrid Journal   (Followers: 2)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 3)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 3)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 5)
Life Sciences in Space Research     Hybrid Journal  
MAD - Magazine of Aviation Development     Open Access  
Microgravity Science and Technology     Hybrid Journal  
New Space     Hybrid Journal   (Followers: 2)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
npj Microgravity     Open Access  
Population Space and Place     Hybrid Journal   (Followers: 2)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access  
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 7)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 40)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 67)
Propulsion and Power Research     Open Access   (Followers: 22)
REACH - Reviews in Human Space Exploration     Full-text available via subscription  
Recent Patents on Space Technology     Full-text available via subscription   (Followers: 1)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 5)
RocketSTEM     Free  
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 23)
Space and Polity     Hybrid Journal   (Followers: 3)
Space Policy     Hybrid Journal   (Followers: 24)
Space Research Today     Full-text available via subscription   (Followers: 40)
Space Safety Magazine     Free   (Followers: 40)
Space Science Reviews     Hybrid Journal   (Followers: 95)
SpaceNews     Free   (Followers: 494)
Transport and Aerospace Engineering     Open Access   (Followers: 5)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 4)
Unmanned Systems     Hybrid Journal   (Followers: 1)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 1)
Вестник УГАТУ     Open Access  

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Journal Cover CEAS Aeronautical Journal
  [SJR: 0.499]   [H-I: 6]   [26 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1869-5582
   Published by Springer-Verlag Homepage  [2336 journals]
  • Design methodology for trailing-edge high-lift mechanisms
    • Authors: David Zaccai; Francesco Bertels; Roelof Vos
      Pages: 521 - 534
      Abstract: Abstract A new methodology has been developed that integrates the preliminary wing design with trailing edge high-lift systems and accounts for three-dimensional flap kinematics. The high-lift system in the developed application includes the kinematic synthesis of four common mechanisms (dropped-hinge, four-bar, link-track and hooked-track) and a preliminary actuation architecture. The paper details how each of these mechanisms is synthesized based on a set of intuitive input requirements such as gap and overlap dimensions in landing and take-off configuration. A SimMechanics multi-body mechanism model is generated to obtain the internal loads of the mechanism and actuation torque. The mechanisms and actuating drive train are structurally sized, leading to a determination of system weight and power consumption. A weight measurement of the outboard hooked-track mechanism of a VFW-614 flap has been compared to a modeled hooked-track mechanism by using the proposed method. This resulted in a 13 % underestimation of the mechanism weight, which was attributed to modeling simplifications, sizing assumptions and a crude aerodynamic load estimation. A comparison study between the four different mechanism types to be applied on a Boeing 777 wing, shows that the method can give the designer valuable insight in the gap/overlap behavior of the flap during deployment as well as an initial estimation of the difference in required fairing size, mechanism weight, and actuation power between the four mechanisms.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0202-7
      Issue No: Vol. 7, No. 4 (2016)
       
  • Impact of pulsed jet actuators on aircraft mass and fuel consumption
    • Authors: Francesco G. A. Bertels; Reinier van Dijk; Reno Elmendorp; Roelof Vos
      Pages: 535 - 549
      Abstract: Abstract Pulsed jet actuators (PJAs) are one of the candidate technologies to be integrated in Fowler flaps to increase the maximum lift coefficient of transport aircraft in the landing configuration. The total system consists of the actuators plus sensors, a piping system to supply pressurized air and a (redundant) power and communication system to provide actuator control. In this paper, it is investigated what increase in the maximum lift coefficient is required to justify the added weight and power off-takes that accompany the integration of pulsed jet actuators. This is done by making an automated design process for the overall aircraft, the piping assembly system, and the electrical wiring interconnection system. These last two sub-systems rely on KBE techniques that automate dimensioning and performance evaluation. A test case is specified that encompasses the design of a typical single-aisle mid-range aircraft with and without the PJA system installed. It is concluded that the introduction of the PJA system requires at least an increase in maximum lift coefficient of 0.2 to justify the increase in system mass and power off-takes. Furthermore, it is shown that if the maximum lift coefficient increases with 0.4, only small reductions in maximum take-off weight (−0.3 %) and operating empty weight (−0.6 %) can be expected, while the total fuel burn remains virtually constant.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0201-8
      Issue No: Vol. 7, No. 4 (2016)
       
  • Investigation of a simplified aerodynamic modelling technique for noise
           predictions using FW–H propagation
    • Authors: Jianping Yin; Berend G. van der Wall; Gunther A. Wilke
      Pages: 551 - 566
      Abstract: Abstract This paper addresses the influence of the elastic rotor blade deformation and the aerodynamic interference from the fuselage on the rotor aerodynamics, including rotor noise characteristics. A BO105 main rotor/fuselage configuration is chosen for the numerical simulations. An unsteady aerodynamic code based on free wake three-dimensional panel method (UPM) is used to account for nonlinear effects associated with the mutual interference between main rotor and fuselage. Airbus Helicopters’ (formerly: Eurocopter) rotor code (HOST) is coupled with this aerodynamic code (UPM) to account for the effect of elastic blade deformation. The effect of the fuselage is simulated using two fuselage models in aerodynamic code, (1) potential theory in the form of a panelized fuselage and (2) an analytic fuselage influence formulation derived from isolated fuselage simulation. The advantage of (2) is in its computational efficiency. The aerodynamic modelling is then coupled with an aero-acoustic post-processing tool based on the Ffowcs-Williams–Hawkings (FW–H) approach for evaluating the noise propagation to the far-field. This toolchain is then evaluated in different flight conditions to assess the usability of this approach in the design process. In descending flight, the acoustic prediction is completed at a very mature level, as the blade vortex interaction is well captured. In climb, the major noise peak is underpredicted, while the overall directivity agreement is well matched. In forward flight, due to a phase shift in the airloads prediction, parts of the loading noise directivity are not well captured. The onset of transonic effects further degrades the results obtained at the front of the rotor. For the investigated flight cases, the analytical fuselage formulation brought very similar results to the panelized fuselage model, therefore proving its worthiness for further accelerating the simulation in these flight conditions.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0208-1
      Issue No: Vol. 7, No. 4 (2016)
       
  • Fiber-reinforced polymers with integrated shape memory alloy actuation: an
           innovative actuation method for aerodynamic applications
    • Authors: M. Hübler; S. Nissle; M. Gurka; U. Breuer
      Pages: 567 - 576
      Abstract: Abstract This contribution focuses on the application potential of active fiber-reinforced polymer (FRP) structures with integrated shape memory alloy (SMA) elements for new aerodynamic functions. The advantages of hybrid SMA FRP structures are highlighted, and promising application concepts are discussed. To illustrate the applicability of the technology, the developed manufacturing, design, and control approaches are presented. Main focus is the development of a new concept for an active aerodynamic airfoil and the realization of a hardware demonstrator. Beginning with the idea of an adaptive airfoil, able to bear an application relevant down force at a relatively high deflection, the design process starts with an evaluation of different actuation concepts. An SMA-powered cantilever is a part of the profile itself. Applying the finite-element method with a suitable model for the active hybrid material, an effective selection of material and design is possible. After manufacturing and assembling of the active hybrid airfoil, a comparison of experimental results and simulation is the first proof of success. Finally, the installation of an integrated hardware setup with power source, control, and the active hybrid structure, demonstrating actuation on demand, verifies the potential and the distinct advantages of the new approach using SMA FRP structures.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0209-0
      Issue No: Vol. 7, No. 4 (2016)
       
  • Analysis of dry-spot behavior in the pressure field of a liquid composite
           molding process
    • Authors: D. Bertling; R. Kaps; E. Mulugeta
      Pages: 577 - 585
      Abstract: Abstract Due to industrial automation of liquid composite molding processes and increasing geometrical complexity of composite components, dry-spots from flow front junctions have become increasingly difficult to avoid. The impact and behavior of voids (microscopic or small macroscopic gas entrapments) during preform impregnation is well known, but no attention is given to dry-spots (large macroscopic gas entrapments). Experiments show that formation of a dry-spot in an early stage of an injection process does not necessarily lead to scrap parts. Therefore, simulation-based predictions of dry-spots are no sufficient condition for identification of unsuitable injection strategies. In this paper, the resolution mechanisms of dry-spots under controlled process conditions are investigated and the resulting findings of fundamental formation- and dispersion-mechanisms are presented.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0207-2
      Issue No: Vol. 7, No. 4 (2016)
       
  • The promised future of multi-core processors in avionics systems
    • Abstract: Abstract Modern airplanes need to satisfy rising requirements in terms of functionality and fuel efficiency per passenger. Therefore, an ever-increasing amount of electronics is being integrated in the airplanes either by adding new functionalities or by exchanging mechanical systems by more complex and highly integrated mechatronic ones, optimizing the space, weight and energy used by the airplane infrastructure. Embedded computers are the base of this development and have to perform more and more tasks with at least the same safety characteristics as before. In the last 15 years, different functions traditionally realized in separated devices must be grouped together in one device to limit the ever-increasing number of computers in new airplanes. For safety reasons, this has only been done based on single-core processors up to now: the multi-core technology cannot insure the same level of confidence as single-core controllers—it was mainly invented to gain performance. But the performance of the current single-core processors adequate for embedded and safety–critical applications is limited and, therefore, restricts the grouping of applications. The automotive industry is confronted with similar but still stronger increasing performance challenges. In this sector, the multi-core processors are already considered as the only known solution to fulfill the rising requirements and are, therefore, expected to completely replace single-core processors in a few years. Specific multi-core processor architectures and functionalities improving safety capabilities have recently been developed. The goal of this contribution is to show how the avionics might benefit from using these safety-oriented automotive multi-core processors.
      PubDate: 2016-12-02
      DOI: 10.1007/s13272-016-0228-x
       
  • Multi-scale analysis and optimisation of three-dimensional woven composite
           structures combining response surface method and genetic algorithms
    • Authors: Xinwei Fu; Sergio Ricci; Chiara Bisagni
      Abstract: Abstract The paper proposes an optimisation strategy for the design of structures made of three-dimensional woven composites. The knowledge of the weaving architecture is essential to properly optimise the design of the structural components subjected to specific load conditions. Owing to the hierarchy and periodicity of the textile composite materials, a multi-scale parameterisation modelling strategy combining the adoption of a representative volume element and periodic boundary conditions is employed to estimate the behaviour of stiffened panels. In order to minimise the expensive computational cost, response surface method techniques are used to generate the approximated structural responses in an efficient and applicable way. The approach here proposed consists of a multi-scale parameterization analysis strategy and an optimisation framework based on the response surface technique and genetic algorithms. The optimal design results are verified by finite element analysis proving that the response surface method integrated with genetic algorithms allows to easily investigate the influence of the fabrics constitutive parameters on the structural behaviour.
      PubDate: 2016-11-24
      DOI: 10.1007/s13272-016-0227-y
       
  • An estimation of the UV radiation inside the cockpits of large commercial
           jets
    • Authors: Ralf Meerkötter
      Abstract: Abstract UV irradiances and UV doses inside the cockpit of large commercial jets are estimated. Results are based on radiative transfer calculations taking into account the spectral transmittances and the limited fields of view of large commercial jet windscreens. In a first step, vertical profiles of UV irradiances for a cloud free atmosphere over snow free and snow covered surfaces and for an atmosphere containing a water cloud layer are simulated. It turns out that the windscreens block the UV-B radiation and transmit parts of the UV-A radiation. Comparing UV irradiances inside and outside the cockpit show that the intensity of UV radiation inside strongly depends on whether the direct sun is entering the cabin or not. Without direct sun the diffuse UV radiation inside the cockpit amounts to about 5% the ambient UV irradiance outside the aircraft. In cases of low sun when direct radiation can reach the pilot, percentages grow from 50 to 100% with increasing solar zenith angle. A water cloud layer between 2 and 4 km increases the UV irradiances inside a cockpit by about 7% at 10 km altitude when compared to the cloud free atmosphere. A snow covered surface causes a similar increase. Finally, and by the aid of MOZAIC waypoint data UV doses were estimated for selected long-distance flights between Europe and the overseas continents North and South America, South Africa, and East Asia. UV doses are affected by takeoff and landing time, by the sun position relative to the aircraft heading during flight, and by the day of the year. UV doses inside the cockpit amount to maximum 60% the UV doses outside at the same altitude, however, in most cases percentages are between about 10 and 40%.
      PubDate: 2016-11-19
      DOI: 10.1007/s13272-016-0225-0
       
  • Experimental investigation and design of a shape-variable compressor
           cascade
    • Authors: J. H. Krone; O. Huxdorf; J. Riemenschneider; H. P. Monner; F. Schur; J. Friedrichs; M. Wiedemann
      Abstract: Abstract The design of jet engine compressor blading always implies a compromise between design and off-design operation. The reason for this is a fixed blade geometry which has to be operated over a wide range of operating conditions. Consequently, maximum achievable efficiencies at design operation are limited by off-design requirements, e.g., a certain stall margin. This paper describes an approach using shape-variable blades equipped with integrated piezoceramic-based macro fiber composite (MFC) Actuators on the blade’s suction and pressure sides. By applying a voltage to these actuators, it is possible to increase and to decrease the blade stagger angle and therefore the blade turning. Compared to a conventional fixed blade profile, the actuated design is thus adaptable within a certain range regarding ambient conditions. The first part of the paper describes the geometry and structure of the shape-variable blades for use in a compressor cascade experiment. In the next part, the three-dimensional deformation behavior of all manufactured blades at different shape conditions is characterized with a photogrammetric measurement system called ATOS. The first results without aerodynamic loads show an average displacement at the trailing edge of approximately Δz ≈ 0.9 mm compared to the non-actuated condition. This corresponds to an average outlet angle variation of approximately ∆κ2 ≈ ± 1°. The third part of the paper presents the results of the low speed cascade experiment using a fully actuated cascade. On the one hand, the objective is to determine the influence of blade actuation on aerodynamic characteristics such as flow outlet angle, total pressure loss and pressure distributions. On the other hand, optical blade displacement measurements are used to investigate combined 2D- and 3D-deformation effects of blade actuation in conjunction with aerodynamic loads. For these measurements, the ATOS system is also used. The wake evaluations show that maximum blade actuation leads to flow outlet angle deviations up to ± 1° which can be described by an almost linear shift of the cascade performance without changing the loss distribution significantly. Furthermore, for the chosen profile this margin is approximately constant over the operating range.
      PubDate: 2016-11-19
      DOI: 10.1007/s13272-016-0224-1
       
  • A two-element high-lift airfoil in disturbed flow conditions
    • Authors: S. Klein; P. Scholz; R. Radespiel
      Abstract: Abstract This contribution presents experimental results of a two-element high-lift airfoil in a disturbed inflow. Permanent disturbances are generated by the wakes of two static airfoils located upstream of the research airfoil, one of which is a planar wake by an infinite airfoil and the other is a longitudinal vortex emanating from a finite wing. The disturbances induce spanwise gradients into the flow. The disturbed flow field is measured by Particle Image Velocimetry. The interaction of the disturbed flow field with the high-lift airfoil is investigated by means of static surface pressure close to the airfoil’s leading- and trailing-edge, as well as surface hotfilm measurements and oil flow visualizations on the high-lift flap. For small and moderate incidences the airfoil is mainly influenced by the circulation induced by the disturbances, which affect the effective flow angles. Local effects that result from the turbulence in the airfoil-wake and the induced transverse velocity of the disturbances are likewise considered. At high angle of attack, the prevailing stall conditions with strong variations in spanwise direction are discussed.
      PubDate: 2016-11-18
      DOI: 10.1007/s13272-016-0221-4
       
  • Design and sizing of a parametric structural model for a UCAV
           configuration for loads and aeroelastic analysis
    • Authors: Arne Voss; Thomas Klimmek
      Abstract: Abstract The authors present the setup of a parametric structural finite element model for the loads and aeroelastic analysis of an unmanned combat air vehicle (UCAV). The DLR-F19 is a “flying wing” configuration with a geometry based on previous research conducted in the scope of the “Mephisto” project and its predecessors “FaUSST” and “UCAV2010”. While a considerable body of knowledge exists regarding conventional configurations, unconventional configurations lack that same level of experience, and data for comparison is rarely available. Using an adequate structural model, the conceptual design stage becomes more sophisticated and already allows for the investigation of physical effects at an early stage of the design process. Strategies for structural modeling and proper condensation, aero-structural coupling, loads integration, control surface attachment, and the use of composite materials are addressed in this paper. The resulting model is sized for minimum structural weight, taking into account 216 load cases. In addition, a comprehensive loads analysis campaign is conducted and the resulting loads are evaluated at defined monitoring stations. In addition to maneuver loads, quasi-static gust loads are calculated using the Pratt formula and compared to results obtained from a dynamic 1-cosine gust simulation. The reasons for higher loads of the Pratt formula based method are discussed. The conclusion is that the Pratt formula is suitable for the preliminary sizing of “flying wing” configurations.
      PubDate: 2016-11-16
      DOI: 10.1007/s13272-016-0223-2
       
  • Sizing of the energy storage system of hybrid-electric aircraft in general
           aviation
    • Authors: I. Geiß; R. Voit-Nitschmann
      Abstract: Abstract The advantages of electric drives and conventional combustion engines can be combined in series hybrid-electric aircraft through appropriate aircraft design. As a consequence, energy-efficient aircraft with sufficient range can be realised in general aviation. The sizing of the energy storage system has a significant impact on the range, the energy consumption, and the related energy cost of the aircraft. In this paper, the boundary conditions for the sizing of the energy storage are analysed. Based upon this, a design for an energy-optimized aircraft will be suggested. The energy consumption of this aircraft will then be compared to modern conventional aircraft.
      PubDate: 2016-11-11
      DOI: 10.1007/s13272-016-0220-5
       
  • Adaptive internal model control research in autonomous landing phase for a
           fixed-wing UAV
    • Authors: Jiu-zhou Gao; Hong-guang Jia
      Abstract: Abstract Autonomous landing is a very complex phase of flight for unmanned aerial vehicle (UAV). Adaptive internal model control (AIMC) is proposed and applied on autonomous landing control system in this paper. Controllers are designed based on the decoupled and linearized models of a sample UAV. Estimation of process model is carried out to enhance system robustness, and filter parameter adjustment is proposed to achieve a good dynamic performance. Control effects are compared and analyzed between IMC and AIMC in different wind conditions which demonstrate that AIMC has better performances than IMC. At last, Monte Carlo simulations prove the system stability.
      PubDate: 2016-10-12
      DOI: 10.1007/s13272-016-0216-1
       
  • Influences of voltage variations on electric power architectures for
           hybrid electric aircraft
    • Authors: Patrick C. Vratny; Holger Kuhn; Mirko Hornung
      Abstract: Abstract Hybrid electric and universally electric aircraft seem to be one possible option to fulfil ambitious future emission and noise reduction targets forced by the European Commission with the Strategic Research and Innovation Agenda and the NASA with the NASA N+3 goals. The overall vehicular efficiency of such concepts can be considerably improved. A key element is the design of the electric power train system with regard to efficiency and also mass. Based on a battery-powered direct current (DC) system architecture, the efficiency impact of different design voltages has been investigated in this paper. The main components within a DC electric architecture are power electronics such as converters and inverters, transmission cables, protection devices and cooling systems. Especially, the power electronics show the highest sensitivity when choosing a design system voltage. Two main losses occur within those components, conduction losses and switching losses. While conduction losses decrease with an increase in the design voltage, switching losses normally increase. Therefore, for a required design power there will be a trade-off between conduction and switching losses. For that purpose, two different architecture design philosophies were investigated to compare the system efficiencies at different design voltages. The first architecture is the constant system voltage (CSV) architecture, which compensates a decreasing output voltage of a battery, and a variable system voltage (VSV) architecture, which does not compensate this voltage drop. It has been identified that for an electric power train system delivering a constant power of 6000 kW, the VSV shows the best efficiency. The optimum system voltage of the VSV architecture is near the operating voltage of the electric motor, while the optimum system voltage of the CSV architecture was identified at higher voltages. These results will serve as baseline for the identification of the best voltage level for a mass- and efficiency-optimized system.
      PubDate: 2016-10-11
      DOI: 10.1007/s13272-016-0218-z
       
  • Multidisciplinary design and aerodynamic assessment of an agile and highly
           swept aircraft configuration
    • Authors: C. M. Liersch; K. C. Huber; A. Schütte; D. Zimper; M. Siggel
      Abstract: Abstract The characteristics of highly swept aircraft configurations have been studied in a series of consecutive research projects in DLR for more than 15 years. Currently, the investigations focus on the generic SACCON UCAV configuration, which was specified in a common effort together with the NATO STO/AVT-161 task group. This paper is the first one in a series of articles presenting the SACCON-related research work within DLR. First, the article describes the conceptual design studies being performed for this aircraft configuration. At this point the question is raised, whether the simple aerodynamic methods used within conceptual design can be applied to such type of aircraft configurations with sufficient accuracy. Thus, the second part of this article provides a comparison of the aerodynamic characteristics of the SACCON configuration predicted by low- and high-fidelity aerodynamic methods, as well as some results from wind tunnel experiments.
      PubDate: 2016-10-01
      DOI: 10.1007/s13272-016-0213-4
       
  • Decision-making for unmanned aerial vehicle operation in icing conditions
    • Authors: S. F. Armanini; M. Polak; J. E. Gautrey; A. Lucas; J. F. Whidborne
      Abstract: Abstract With the increased use of unmanned aerial systems (UAS) for civil and commercial applications, there is a strong demand for new regulations and technology that will eventually permit for the integration of UAS in unsegregated airspace. This requires new technology to ensure sufficient safety and a smooth integration process. The absence of a pilot on board a vehicle introduces new problems that do not arise in manned flight. One challenging and safety-critical issue is flight in known icing conditions. Whereas in manned flight, dealing with icing is left to the pilot and his appraisal of the situation at hand; in unmanned flight, this is no longer an option and new solutions are required. To address this, an icing-related decision-making system (IRDMS) is proposed. The system quantifies in-flight icing based on changes in aircraft performance and measurements of environmental properties, and evaluates what the effects on the aircraft are. Based on this, it determines whether the aircraft can proceed, and whether and which available icing protection systems should be activated. In this way, advice on an appropriate response is given to the operator on the ground, to ensure safe continuation of the flight and avoid possible accidents.
      PubDate: 2016-10-01
      DOI: 10.1007/s13272-016-0215-2
       
  • An innovative route from wind tunnel experiments to flight dynamics
           analysis for a highly swept flying wing
    • Authors: J. Schwithal; D. Rohlf; G. Looye; C. M. Liersch
      Abstract: Abstract A flying wing configuration with highly swept leading edges and low aspect ratio such as the generic UCAV configuration DLR-F19 is very attractive for military applications due to its very favorable stealth capabilities as well as its high agility. To assure good flying qualities, however, is a critical aspect for such a configuration. It should thus be considered early in the design process. This paper presents an innovative way to derive a flight dynamics model from wind tunnel experiments by applying a system identification approach, normally employed for flight tests. This allows the modelling of nonlinear aerodynamic effects and provides a model which can be integrated directly into flight dynamics simulations. New wind tunnel maneuvers are applied, which significantly reduce the time of the wind tunnel experiments and improve the quality of the aerodynamic dataset generation. The aerodynamic model is then integrated into a 6-degrees-of-freedom simulation environment to perform a flight dynamics analysis of the UCAV configuration. The purpose of this analysis is to compare the flying qualities as derived from wind tunnel data with the numerical results determined on the basis of potential flow methods used in preliminary aircraft design.
      PubDate: 2016-09-24
      DOI: 10.1007/s13272-016-0214-3
       
  • Characteristic flight speeds in bats
    • Abstract: Abstract We present empirical data on flight speed for 30 species of Australian bats representing seven families. These data show five characteristic level flight speeds: ‘minimum’ (V min), ‘best efficiency’ (V eff), ‘most common’ (V mode), ‘maximum cruise’ (V mcr) and ‘maximum spurt’ (V msp). Next, we calculate V min, V eff, ‘maximum aerobic’ (V ae), ‘sustainable anaerobic’ (V san ) and ‘maximum anaerobic’ (V man) flight speeds using a published quasi-steady model. Model predictions were within 0.5 m s−1 of the empirical values for all five characteristic speeds given adequate samples. Model fidelity was cross-checked using flight speed data published for other Old and New World species.
      PubDate: 2016-09-19
      DOI: 10.1007/s13272-016-0212-5
       
  • Multiscale virtual testing: the roadmap to efficient design of composites
           for damage resistance and tolerance
    • Authors: C. S. Lopes; C. González; O. Falcó; F. Naya; J. LLorca; B. Tijs
      Abstract: Abstract This paper proposes a novel approach to the determination of the mechanical behaviour of composite materials up to failure using numerical and experimental techniques in parallel. A bottom-up multiscale virtual testing strategy is presented to take into account the physical mechanisms of deformation at different length scales on the behaviour of the composite. Starting from the microscale, the contributions of the basic constituents, microstructure and loading conditions to the mechanical response are considered in a rigorous way. This hierarchical multiscale approach describes systematically the material behaviour at different length scales from ply to laminate to component level, allowing the determination of ply properties, laminate characteristics and structural response. Additionally, this approach easily allows consideration of changes in properties of the constituents (fibre, matrices), fibre architecture or laminate lay-up and provides fast predictions of their influences on the macroscopic behaviour of composite structures. Hence, this approach constitutes a promising tool to provide significant efficiency gains in the design, testing and certification of composite aircraft structures.
      PubDate: 2016-09-16
      DOI: 10.1007/s13272-016-0210-7
       
  • Handling qualities evaluation of an automatic slung load stabilization
           system for rescue hoist operations
    • Authors: D. Nonnenmacher; M. Jones
      Abstract: Abstract The Handling Qualities (HQs) of a helicopter can be adversely affected through the presence of an externally slung load. Helicopter stability margins may be reduced, due to the additional dynamics of the load system, which can subsequently increase pilot workload, and reduce the operational envelope. An Automatic Load Damping System (ALDS) has been designed and has been successfully tested in flight. This system, alongside slung load scenarios, has been implemented within a piloted simulation in DLR’s Air Vehicle Simulator. In this article, the results from a simulated test campaign to observe the influence of the stabilization system on the vehicle HQs are presented. The system is assessed using three Mission Task Elements, modified for hoist operations. Results show that a conflict between pilot control and commanded inputs from the ALDS can cause unstable slung load oscillations and degradation in HQs in hover. However, it is shown that when the stabilization system is used only when required, both the HQs of the helicopter are conserved, and load oscillations are reduced. The results in this paper are intended to motivate future flight tests using DLR’s Active Control Technology/Flying Helicopter Simulator.
      PubDate: 2016-09-14
      DOI: 10.1007/s13272-016-0211-6
       
 
 
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