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 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 99 journals)
 Showing 1 - 30 of 30 Journals sorted alphabetically Acta Astronautica       (Followers: 353) Advances in Space Research       (Followers: 353) Aerospace       (Followers: 40) Aerospace and Electronic Systems, IEEE Transactions on       (Followers: 229) Aerospace Science and Technology       (Followers: 325) Aerospace Scientific Journal       (Followers: 2) AIAA Journal       (Followers: 796) Air Force Magazine       (Followers: 9) Air Medical Journal       (Followers: 5) Aircraft Engineering and Aerospace Technology       (Followers: 176) American Journal of Space Science       (Followers: 133) Annual of Navigation       (Followers: 21) Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences       (Followers: 19) ASTRA Proceedings       (Followers: 1) Aviation       (Followers: 12) Aviation Psychology and Applied Human Factors       (Followers: 19) Aviation Week       (Followers: 250) Aviation, Space, and Environmental Medicine       (Followers: 9) Canadian Aeronautics and Space Journal       (Followers: 29) CEAS Aeronautical Journal       (Followers: 28) Chinese Journal of Aeronautics       (Followers: 18) Ciencia y Poder Aéreo       (Followers: 1) Civil Aviation High Technologies Control Systems       (Followers: 187) Cosmic Research       (Followers: 3) COSPAR Colloquia Series       (Followers: 7) Egyptian Journal of Remote Sensing and Space Science       (Followers: 19) Elsevier Astrodynamics Series       (Followers: 9) Fatigue of Aircraft Structures       (Followers: 12) Frontiers in Astronomy and Space Sciences       (Followers: 9) Gyroscopy and Navigation       (Followers: 200) IEEE Aerospace and Electronic Systems Magazine       (Followers: 145) IEEE Transactions on Circuits and Systems I: Regular Papers       (Followers: 30) International Journal of Aeroacoustics       (Followers: 34) International Journal of Aerodynamics       (Followers: 20) International Journal of Aerospace Engineering       (Followers: 66) International Journal of Aerospace Sciences       (Followers: 23) International Journal of Applied Geospatial Research       (Followers: 4) International Journal of Aviation Management       (Followers: 4) International Journal of Aviation Psychology       (Followers: 14) International Journal of Aviation Technology, Engineering and Management       (Followers: 5) International Journal of Crashworthiness       (Followers: 9) International Journal of Micro Air Vehicles       (Followers: 8) International Journal of Satellite Communications Policy and Management       (Followers: 9) International Journal of Space Science and Engineering       (Followers: 8) International Journal of Space Structures       (Followers: 9) International Journal of Space Technology Management and Innovation       (Followers: 5) International Journal of Sustainable Aviation       (Followers: 2) International Journal of Turbo & Jet-Engines       (Followers: 4) Journal of Aeronautical Materials       (Followers: 6) Journal of Aeronautics & Aerospace Engineering       (Followers: 15) Journal of Aerospace Engineering       (Followers: 59) Journal of Aerospace Engineering & Technology       (Followers: 11) Journal of Aerospace Information Systems       (Followers: 13) Journal of Aerospace Technology and Management       (Followers: 4) Journal of Aircraft       (Followers: 218) Journal of Airline and Airport Management       (Followers: 7) Journal of Astrobiology & Outreach       (Followers: 1) Journal of Aviation Technology and Engineering       (Followers: 10) Journal of Engineering and Technological Sciences Journal of Guidance, Control, and Dynamics       (Followers: 138) Journal of Konbin : The Journal of Air Force Institute of Technology       (Followers: 2) Journal of Navigation       (Followers: 210) Journal of Propulsion and Power       (Followers: 382) Journal of Space Safety Engineering       (Followers: 1) Journal of Space Weather and Space Climate       (Followers: 21) Journal of Spacecraft and Rockets       (Followers: 557) Journal of Spatial Science       (Followers: 3) Journal of the American Helicopter Society       (Followers: 5) Journal of the Astronautical Sciences       (Followers: 5) Journal of Wind Engineering and Industrial Aerodynamics       (Followers: 7) Life Sciences in Space Research       (Followers: 2) MAD - Magazine of Aviation Development       (Followers: 1) Microgravity Science and Technology       (Followers: 1) New Space       (Followers: 4) Nonlinear Dynamics       (Followers: 16) npj Microgravity       (Followers: 1) Population Space and Place       (Followers: 5) Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering       (Followers: 1) Proceedings of the Human Factors and Ergonomics Society Annual Meeting       (Followers: 10) Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering       (Followers: 41) Progress in Aerospace Sciences       (Followers: 75) Propulsion and Power Research       (Followers: 26) REACH - Reviews in Human Space Exploration       (Followers: 2) Recent Patents on Space Technology       (Followers: 3) Research & Reviews : Journal of Space Science & Technology       (Followers: 9) RocketSTEM       (Followers: 3) Russian Aeronautics (Iz VUZ)       (Followers: 23) Science and Education : Scientific Publication of BMSTU Space and Polity       (Followers: 4) Space Policy       (Followers: 25) Space Research Today       (Followers: 43) Space Safety Magazine       (Followers: 43) Space Science Reviews       (Followers: 93) SpaceNews       (Followers: 548) Transport and Aerospace Engineering       (Followers: 5) Transportmetrica A : Transport Science       (Followers: 5) Unmanned Systems       (Followers: 3) Вісник Національного Авіаційного Університету       (Followers: 1)
 CEAS Aeronautical Journal   [SJR: 0.499]   [H-I: 6]   [28 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1869-5582    Published by Springer-Verlag  [2352 journals]
• Authors: Paul H. Lehmann; Michael Jones; Marc Höfinger
Pages: 413 - 428
Abstract: Abstract Offshore helicopter operations are frequently conducted in both turbulent and degraded visual environments (DVE). This investigation assesses the combined influence of turbulence and DVEs on pilot workload to identify first limits for safe operations. Flight tests using a simulation model of the research helicopter ACT/FHS (active control technology/flying helicopter simulator) flight mechanics model were conducted in the air vehicle simulator (AVES) at DLR Braunschweig. Tests were completed using four pilots, and results show the effects on pilot workload, task performance and control input activity. It was found that DVE and turbulence increase the workload and reduce task performance, but each in a different manner. Furthermore, the impact on control activity and pilot-induced oscillation tendencies are shown to have dependency upon the environmental conditions.
PubDate: 2017-09-01
DOI: 10.1007/s13272-017-0246-3
Issue No: Vol. 8, No. 3 (2017)

• Benefit evaluation of hybrid electric propulsion concepts for CS-23
aircraft
• Authors: M. Kreimeier; E. Stumpf
Abstract: Abstract The importance of small passenger aircraft design fitting up to nine passengers and the evaluation of associated technologies have been recently increasing. This is related to the upcoming interest in on demand air mobility concepts not only for intra- or inter-urban transport but also for thin-haul routes ranging from 150 km to approximately 500–800 km. Such concepts seem feasible as key enabling technologies (e.g., flight automation and battery technology) are likely to be mature enough to enable these concepts in the foreseeable future. However, until battery specific energy in particular surpasses the threshold of approximately 400 Wh/kg, hybrid electric propulsion concepts could serve as an interim solution. Therefore, this paper deals with the question of how hybrid electric concepts score compared to conventional piston engine aircraft and which concept promises the most benefits. This includes consideration of propulsion-airframe integration benefits of electric engines through distributed electric propulsion (DEP). Results show that the series hybrid electric concept is superior to a parallel setup if at least a 15% higher cruise lift-to-drag ratio can be achieved due to DEP (30–50% increase likely). Despite higher weight, variable operating costs can be reduced by 15–35% with application of series hybrid electric propulsion concepts.
PubDate: 2017-10-14
DOI: 10.1007/s13272-017-0269-9

• Multidisciplinary optimization of an NLF forward swept wing in combination
with aeroelastic tailoring using CFRP
• Authors: Tobias Wunderlich; Sascha Dähne; Lars Heinrich; Lars Reimer
Abstract: Abstract This article introduces a process chain for commercial aircraft wing multidisciplinary optimization (MDO) based on high fidelity simulation methods. The architecture of this process chain enables two of the most promising future technologies in commercial aircraft design in the context of MDO. These technologies are natural laminar flow (NLF) and aeroelastic tailoring using carbon fiber reinforced plastics (CFRP). With this new approach, the application of MDO to an NLF forward swept composite wing will be possible. The main feature of the process chain is the hierarchical decomposition of the optimization problem into two levels. On the highest level, the wing planform including twist and airfoil thickness distributions as well as the orthotropy direction of the composite structure will be optimized. The lower optimization level includes the wing box sizing for essential load cases considering the static aeroelastic deformations. In addition, the airfoil shapes are transferred from a given NLF wing design and the natural laminar flow is considered by prescribing laminar–turbulent transition locations. Optimization results of the multidisciplinary process chain are presented for a forward swept wing aircraft configuration on conceptual design level. The results show a fuel burn reduction in the order of 9% for the design mission.
PubDate: 2017-10-10
DOI: 10.1007/s13272-017-0266-z

• Aileron endurance test rig design based on high fidelity mathematical
modeling
Abstract: Abstract This paper presents a model-based approach to design aileron endurance test rig (ETR). ETR is a dynamic load simulator which simulates aerodynamic load on-ground for verifying and validating the design, performance and stability of aileron actuator. Aileron actuator is a servo-controlled linear hydraulic actuator used to control the movement of ailerons in aircraft. Aileron is one of the primary flight control surfaces which controls roll of the aircraft. In ETR, Aileron actuator acts as unit under test (UUT) while a double-acting linear hydraulic actuator produces a dynamic load with the help of high pressure fluid source and electro-hydraulic servo valve (EHSV). The design of the test rig depends on load and velocity requirements which vary widely over the whole flight envelop and depends on deflection of surface, angle of attack, aircraft speed and altitude. One of the critical factor in designing ETR is to accurately model the interaction between the UUT and load system. This paper presents a simple yet powerful approach of free body diagram to account the power flow between the two systems. Model-based approach allowed to simulate the complete test rig behavior identifying the values of the critical parameters prior to building it. A high fidelity, non-linear mathematical model of aileron ETR is developed, simulated and verified. An appropriate load actuator and its electro-hydraulic servo valve are chosen to meet load and velocity requirements. The minimum rig structure stiffness is determined to ensure the stability of the load control system. A velocity feed-forward-based load controller along with proportional-integral control is implemented and tuned to meet the load control performance satisfactorily. Finally, the developed model is validated against the experimental data from actual test rig.
PubDate: 2017-10-07
DOI: 10.1007/s13272-017-0267-y

• In-flight tracking and vibration control using the DLR’s multiple
Swashplate system
• Authors: Philip M. Küfmann; Claudio Brillante
Abstract: Abstract This paper discusses the design, integration, and test of a higher harmonic control algorithm capable of both vibration control and in-flight blade tracking in conjunction with DLR’s multiple swashplate control system (META), while honoring predefined limits in usable control authority. The design of the control algorithm is described in detail and the results of coupled numerical investigations with both a general purpose multibody code by Politecnico di Milano and DLR’s comprehensive rotor code to determine the algorithm’s performance are presented. The integration of the control algorithm into the real-time control software is shown for the META system, where, for safety reasons, a semi-open loop approach was implemented. First tests of the controllers in-flight tracking mode to reduce 1/rev loads during hover yielded an almost complete reduction in 1/rev vibratory loads while maintaining constant rotor thrust. Following the experiments at DLR’s own facility, extensive wind-tunnel tests were performed in 2016 with META and a 5-bladed rotor system at the large low-speed facility of the German Dutch Wind Tunnels. The control algorithm was adapted to the 5-bladed rotor and successfully applied for in-flight blade tracking as well as the reduction of 5/rev hub loads using multi-harmonic pitch inputs with frequencies from 4/rev to 6/rev in cruise and high-speed flight condition. In both cases, the controller showed excellent performance and yielded satisfactory reductions of 1/rev rotor imbalances as well as a reduction of 5/rev hub vibrations by more than $$80\%$$ , while, at the same time, adhering to user set limits for the higher harmonic control amplitudes.
PubDate: 2017-10-03
DOI: 10.1007/s13272-017-0265-0

• Flight mechanics model for spanwise lift and rolling moment distributions
of a segmented active high-lift wing
• Authors: J. H. Diekmann; D. Keller; E. Faez; R. Rudnik; V. Gollnick
Abstract: Abstract In this study, the aerodynamics of wings using an active high-lift system are investigated. The target is the flight mechanical description of the spanwise forces and resulting moments and the influence of the active high-lift system to their distribution. The high-lift system is a blown flap system divided into six segments per wing. Each segment is assumed to be individually controlled, so the system shall be used for aircraft control and system failure management. This work presents a flight mechanical sub-model for the simulation of flight dynamics, which has been derived from high-fidelity CFD results. An assessment of single-segment blowing system failures will be presented including recommendations for compensation of either lift or rolling moment loss. For this investigation, the compensation is required to act at the same wing side on which the failure appears. Thus, the potential for an increase of system reliability shall be proven. The results show that less performance investment in terms of pressurized air is necessary to compensate the rolling moment of a failing segment instead of its lift. However, large blowing performance increases for the remaining wing segments that occur for some of the failure cases.
PubDate: 2017-09-20
DOI: 10.1007/s13272-017-0261-4

• Boundary-layer transition measurements on Mach-scaled helicopter rotor
• Authors: Armin Weiss; Anthony D. Gardner; Christian Klein; Markus Raffel
Abstract: Abstract In this work, laminar-turbulent boundary-layer transition is investigated on the suction side of Mach-scaled helicopter rotor blades in climb. The phenomenon is assessed by means of temperature-sensitive paint (TSP). Results are compared to a data sample acquired by infrared (IR) thermography and accompanied by integral thrust- and local surface pressure measurements at two radial blade sections. Spatially, high-resolved data allow for precise detection of boundary-layer transition along the outer 60% of the blade span. Results obtained via TSP and IR show remarkable agreement with minor deviations due to different surface qualities of the respective blades tested. TSP data are obtained at various collective pitch angles and three different rotating speeds corresponding to chord Reynolds and Mach numbers based on blade tip speed of $$Re_{\rm tip} = 4.8 - 9.3\times 10^5$$ and $$M_{\rm tip} = 0.29 - 0.57$$ , respectively. The transition position is detected with an accuracy of better than 1% chord and the findings show overall coherence as blade loading and tip chord Reynolds number are varied. Experimental findings are shown to be consistent with two-dimensional simulations using the $$e^N$$ -envelope method for transition prediction. Based on quantitative agreement between measured and calculated surface pressures, a comparison of the corresponding transition results suggests a critical amplification factor of $$N_{\rm cr.} = 5.5$$ best suited for transition prediction in the rotating test facility of the DLR Göttingen.
PubDate: 2017-09-19
DOI: 10.1007/s13272-017-0263-2

• Numerical modelling of the aerodynamic interference between helicopter and
ground obstacles
• Authors: Giulia Chirico; Damien Szubert; Luigi Vigevano; George N. Barakos
Abstract: Abstract Helicopters are frequently operating in confined areas where the complex flow fields that develop in windy conditions may result in dangerous situations. Tools to analyse the interaction between rotorcraft wakes and ground obstacles are therefore essential. This work, carried out within the activity of the GARTEUR Action Group 22 on “Forces on Obstacles in Rotor Wake”, attempts to assess numerical models for this problem. In particular, a helicopter operating in hover above a building as well as in its wake, one main rotor diameter above the ground, has been analysed. Recent tests conducted at Politecnico di Milano provide a basis for comparison with unsteady simulations performed, with and without wind. The helicopter rotor has been modelled using steady and unsteady actuator disk methods, as well as with fully resolved blade simulations. The results identify the most efficient aerodynamic model that captures the wakes interaction, so that real-time coupled simulations can be made possible. Previous studies have already proved that the wake superposition technique cannot guarantee accurate results if the helicopter is close to the obstacle. The validity of that conclusion has been further investigated in this work to determine the minimum distance between helicopter and building at which minimal wake interference occurs.
PubDate: 2017-09-05
DOI: 10.1007/s13272-017-0259-y

• Adaptive backstepping neural network control for three dimensions
trajectory tracking of robotic airships
• Authors: Yueneng Yang; Wenqiang Wang; Ye Yan
Abstract: Abstract The robotic airship provides a unique aerostatic platform for various applications, and these applications require high-precise trajectory tracking. However, it is a challenging problem due to nonlinearity and uncertainty of airship dynamics. This paper proposes an adaptive backstepping neural network control (ABNNC) approach to address this problem. First, the kinematics model and dynamics model of the robotic airship are presented. Second, the control problem of trajectory tracking is formulated, and a trajectory controller is designed using backstepping approach. A radial basis function neural network (RBFNN) is employed to approximate the uncertain dynamics model of the airship, and an adaptive law is designed to update the NN weight in the processing of approximation. The ultimate boundedness of the tracking errors are proven based on the Lyapunov theory. Finally, simulations are presented to illustrate the effectiveness and high precision of the designed controller.
PubDate: 2017-09-04
DOI: 10.1007/s13272-017-0262-3

• Support of icing flight tests by near real-time data analysis
• Authors: Christian Raab; Per Ohme; Christoph Deiler
Abstract: Abstract Flight testing of aircraft with altered aerodynamic configuration is a safety critical and time consuming task. For the evaluation of the aircraft characteristics under SLD icing conditions, flight tests with artificial ice shapes were performed. These flight tests were supported by online algorithms for the estimation of aerodynamic parameters. Results were available in near real-time onboard the aircraft or already during the debriefing on ground. Pre-flight data from wind tunnel experiments could be confirmed already during the flight using these online analysis tools, thus the flight tests could be performed in shorter time and more safe. This paper will introduce the developed analysis tools and will present results from the flight test campaign.
PubDate: 2017-08-31
DOI: 10.1007/s13272-017-0260-5

• High-speed PIV applied to wake of NASA CRM model at high Re-number sub-
and transonic stall conditions
• Authors: Robert Konrath; Reinhard Geisler; Janos Agocs; Hauke Ehlers; Florian Philipp; Jürgen Quest
Abstract: Abstract Within the framework of the EU project ESWIRP, the particle image velocimetry (PIV) using high-speed camera and laser has been used to measure the turbulent flow in the wake of a stalled aircraft wing. The measurements took place on the common research model provided by NASA in the pressurized cryogenic European Transonic Wind tunnel. A specific cryoPIV system has been used and adapted for using high-speed PIV components under the cryogenic conditions of the wind tunnel facility. First results are presented comprising transonic and subsonic stall conditions at realistic flight Reynolds numbers of 11.6 and 30 million, respectively.
PubDate: 2017-08-23
DOI: 10.1007/s13272-017-0258-z

• Towards the development of a flight training programme for future personal
aerial vehicle users
• Authors: Philip Perfect; Michael Jump; Mark D. White
Abstract: Abstract Interest in personal aerial vehicles (PAVs) is resurgent with several flying prototypes made possible through advances in the relevant technologies. Whilst the perceived wisdom is that these vehicles will be highly automated or autonomous, the current regulatory framework assumes that a human will always be able to intervene in the operation of the flight. This raises the possibility of manually operated PAVs and the requirement for an occupant flying training programme. This paper describes the development of training requirements for PAV pilots. The work includes a training needs analysis (TNA) for a typical PAV flight. It then describes the development of a training programme to develop the skills identified by the TNA. Five participants with no real flying experience, but varying levels of driving experience, undertook the training programme. Four completed the programme through to a successful simulation flight test of a commuter flight scenario. These participants evaluated the effectiveness of the training programme using the first three Levels of Kirkpatrick’s method. The evaluation showed that the developed training programme was effective, in terms of both trainee engagement and development of the handling skills necessary to fly PAV mission-related tasks in a flight simulator. The time required for the four successful participants to develop their core flying skills was less than 5 h. This duration indicates that future simulation PAV training would be commensurate with the training duration for current personal transportation modes.
PubDate: 2017-07-17
DOI: 10.1007/s13272-017-0255-2

• Motion cueing optimisation applied to rotorcraft flight simulation
• Authors: Michael Jones
Abstract: Abstract Achieving good motion cueing in rotorcraft flight simulation is a long-standing challenge in the simulation community. The current reliance upon subjective opinion leads to a wide range of motion configurations, which almost certainly do not offer the optimal level of vestibular cueing. Furthermore, without the understanding of the optimal motion settings, objective criteria are difficult to apply. This paper presents a new method designed to optimise and evaluate the response of any motion platform, based upon the input to the system and the given motion system constraints. The method is utilised to tune the motion platform of the air vehicle simulator. Results show promise for the use of the optimisation, as good fidelity is shown through pilot subjective comments and ratings.
PubDate: 2017-07-14
DOI: 10.1007/s13272-017-0256-1

• Comparison of the NASA Common Research Model European Transonic Wind
Tunnel test data to NASA National Transonic Facility test data
• Authors: Melissa Rivers; Jürgen Quest; Ralf Rudnik
Abstract: Abstract Experimental aerodynamic investigations of the NASA Common Research Model have been conducted in the NASA Langley National Transonic Facility and the European Transonic Wind Tunnel. Data have been obtained at chord Reynolds numbers of 5, 19.8 and 30 million for the wing/body/tail = 0° incidence configuration in the National Transonic Facility and in the European Transonic Wind Tunnel. Force and moment, surface pressure, wing bending and twist, and surface flow visualization data were obtained in both facilities but only the force and moment, and surface pressure data are presented herein.
PubDate: 2017-07-12
DOI: 10.1007/s13272-017-0250-7

• Numerical simulation of flexible aircraft structures under ditching loads
• Authors: M. H. Siemann; D. Kohlgrüber; H. Voggenreiter
Abstract: Abstract Aircraft certification requires demonstrating an aircraft’s structural capacity to withstand hydrodynamic loads as experienced during an emergency landing on water known as ditching. Currently employed means to analyze ditching comprise comparison with previously certified aircraft, sub-scale experimental testing, and semi-analytical as well as uncoupled computational methods; all of these are subject to simplifications that limit their predictability and accuracy. Therefore, there is the motivation to employ advanced, coupled numerical simulations to enhance the analysis capabilities. This paper presents a numerical simulation approach combining Smoothed Particle Hydrodynamics and Finite Element method, which permits investigating the structural behavior under ditching loads within one simulation. Comprehensive validation studies based on comparison with experimental results from novel guided ditching experiments of generic panels in aeronautical design have been undertaken and high accuracy has been achieved regarding acting force and strain time histories. Additionally, the profound analysis of the structural behavior of flexible panels allows assessing the main mechanisms that cause the acting hydrodynamic loads to increase significantly when the structure is being deformed. Presented results extend the fundamental knowledge in this field. The validated simulation approach is finally applied to analyze the structural behavior of a detailed stringer-frame-reinforced panel representing a generic aircraft bottom fuselage structure. Comparison between the structural behavior of the generic panels and the aft fuselage structure is established. Furthermore, conclusions with regard to ditching simulations involving larger or even full aircraft structures are drawn.
PubDate: 2017-07-11
DOI: 10.1007/s13272-017-0257-0

• Aerodynamic assessment of nozzle area variation by core fairing modulation
• Authors: Chetan Kumar Sain; Klaus Hoeschler
Abstract: Abstract This paper describes the aerodynamic assessment of a particular variable area fan nozzle (VAFN) concept. This concept offers a variation in the fan nozzle throat area by displacing the inner fairing structure (IFS), which is also known as the core fairing structure. A few different design configurations were developed through the variation in the design parameters. The aim of the assessment was to perform a comparative aerodynamic study by evaluating the main performance parameters such as the nozzle thrust coefficient, nozzle discharge coefficient and the after-body drag at different flight conditions. The required boundary conditions and the magnitudes of the variation in the nozzle throat area were defined following the performance calculations of the whole engine.
PubDate: 2017-07-05
DOI: 10.1007/s13272-017-0253-4

• Aeroelastic tailoring of an NLF forward swept wing
• Authors: Tobias Wunderlich; Sascha Dähne
Abstract: Abstract This article introduces the application of a multidisciplinary analysis process chain based on high-fidelity simulation methods for the aeroelastic tailoring of an natural laminar flow (NLF) forward swept wing. With this approach the interactions between aerodynamics, loads and structural sizing are considered in the wing analysis. The resulting process enables an integrated aerostructural wing design including aeroelastic tailoring using carbon fiber reinforced plastics. The main feature of the process chain is the hierarchical decomposition of the problem into two levels. On the highest level, the orthotropy direction of the composite structure will be analyzed. The lower level includes the wing box sizing for essential load cases considering the static aeroelastic deformations. Thereby, the wing box sizing can be performed with a given ply share of the laminate or a ply share optimization. Additionally, the airfoil shapes are transferred from a given NLF wing design. The natural laminar flow is considered by prescribing laminar–turbulent transition locations. The process chain evaluates the wing mass, the lift-to-drag ratio under cruise flight conditions and the corresponding design mission fuel consumption. Results of aerostructural wing design studies and optimizations are presented for an NLF forward swept wing aircraft configuration. The aerostructural wing optimization with 3 orthotropy angles as design parameters shows a wing mass reduction in the order of 8% and a design mission fuel consumption reduction in the order of 4% in comparison to the aeroelastic tailored wing design of the reference aircraft.
PubDate: 2017-06-30
DOI: 10.1007/s13272-017-0251-6

• Automated trajectory generation and airport selection for an emergency
landing procedure of a CS23 aircraft
• Authors: Arno Fallast; Bernd Messnarz
Abstract: Abstract Aircraft in general aviation usually are operated in single pilot mode. Especially, in case of an incapability of the pilot to control the aircraft, an automated emergency procedure is desirable in order to reduce the risk of fatalities. The finding of a solution for an emergency landing maneuver includes preselecting possible landing sites with regard to the available aircraft capabilities and creation of feasible trajectories to these sites. A search tree in four-dimensional search space with an efficient implementation of a rapidly exploring random tree algorithm (RRT*) is created. The algorithm performance is increased by use of basic geometrical sets to construct the final route as a combination of Dubins path segments. To further reduce the route length, a gradient based local optimization routine is added after completion of the RRT* algorithm. At the moment of creation, terrain avoidance is verified and accordance with legal airspace structure is considered. An emergency procedure is created by combining a selected landing site and a flyable trajectory to this site. Each of these combinations is scored, and the most promising emergency landing procedure is chosen and delivered to flight management system of the aircraft. The flight management system controls a full-authority auto-flight system that is capable of performing en-route flight and auto-land procedures as well.
PubDate: 2017-06-30
DOI: 10.1007/s13272-017-0252-5

• Numerical and experimental investigations of the propeller characteristics
of an electrically powered ultralight aircraft
• Authors: M. Stuhlpfarrer; A. Valero-Andreu; C. Breitsamter
Abstract: Abstract The performance and efficiency of a propeller is crucial for electrically powered propulsion systems. Since the energy of the batteries is limited, it is important to develop propellers with high efficiency. Therefore, numerical and experimental investigations of the propeller characteristics are performed. The wind tunnel experiments are performed on a fuselage–propeller configuration. The electrical motor, batteries, and control units are designed to be integrated in the fuselage. Furthermore, force measurements are conducted to provide a data base for the validation of the numerical results. Two different numerical approaches are presented. First, the propeller is fully resolved by applying a rotational domain and a sliding mesh interface. Second, an actuator disk approach including blade element theory with a panel method one-way coupled with a boundary layer integration method is presented. The latter shall be used to reduce computational and mesh generation costs. The thrust, efficiency as well as pressure distribution and the flow field downstream of the propeller are analyzed. The obtained numerical results show a good agreement with the experimental data for the integral values over a wide operating range. Moreover, the results of the inter-method comparison of the two numerical approaches are in a good accordance regarding the local effects for the two highlighted operating points.
PubDate: 2017-06-16
DOI: 10.1007/s13272-017-0245-4

• Experimental study of two electro-mechanical de-icing systems applied on a
wing section tested in an icing wind tunnel
• Authors: M. Endres; H. Sommerwerk; C. Mendig; M. Sinapius; P. Horst
Abstract: Abstract Two electro-mechanical de-icing systems are presented, which are applied to a test specimen consisting of a wing section with an NACA0012 profile. The test specimen is of a modular design to be able to substitute the leading edge section for investigating the different de-icing systems. The de-icing tests are performed in the icing wind tunnel of the Institute of Fluid Mechanics of the TU Braunschweig. The first de-icing concept is an electro-mechanical system based on structural vibrations of the unstiffened sections. Due to piezoceramic actuators and their positions, the skin is excited at its natural frequency. The actuators are placed at the inner side of the leading edge. The second system under investigation is the Electro-Impulse De-Icing concept. Coils placed underneath the upper and lower aluminum skin are supplied with short, high-current impulses which produce opposing time-dependent magnetic fields around coil and skin. The resulting magnetic forces repel the structure which leads to a damped oscillation of the skin. The first aim of this work is to investigate the performance of the two electro-mechanical de-icing systems under various icing conditions. Operational parameters like temperature and liquid water content are varied. The test results show that the de-icing performance of both systems mainly depends on the ice layer thickness and the environmental temperature. The second aim of this work is to investigate the de-icing mechanism of the accumulated ice. Therefore, the de-icing procedure is recorded with a high-speed camera.
PubDate: 2017-06-09
DOI: 10.1007/s13272-017-0249-0

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