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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 97 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 378)
Advances in Space Research     Full-text available via subscription   (Followers: 371)
Aerospace     Open Access   (Followers: 45)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 250)
Aerospace Science and Technology     Hybrid Journal   (Followers: 339)
Aerospace Scientific Journal     Open Access   (Followers: 5)
AIAA Journal     Full-text available via subscription   (Followers: 827)
Air Force Magazine     Full-text available via subscription   (Followers: 9)
Air Medical Journal     Hybrid Journal   (Followers: 5)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 190)
Annual of Navigation     Open Access   (Followers: 22)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 21)
ASTRA Proceedings     Open Access   (Followers: 1)
Aviation     Hybrid Journal   (Followers: 13)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 19)
Aviation Week     Full-text available via subscription   (Followers: 263)
Aviation, Space, and Environmental Medicine     Full-text available via subscription   (Followers: 10)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 29)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 28)
Chinese Journal of Aeronautics     Open Access   (Followers: 18)
Ciencia y Poder Aéreo     Open Access   (Followers: 1)
Civil Aviation High Technologies     Open Access  
Control Systems     Hybrid Journal   (Followers: 207)
Cosmic Research     Hybrid Journal   (Followers: 3)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 7)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 20)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 10)
Fatigue of Aircraft Structures     Open Access   (Followers: 12)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 10)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 206)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 157)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 30)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 36)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 23)
International Journal of Aerospace Engineering     Open Access   (Followers: 70)
International Journal of Aerospace Sciences     Open Access   (Followers: 25)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 5)
International Journal of Aviation Management     Hybrid Journal   (Followers: 5)
International Journal of Aviation Psychology     Hybrid Journal   (Followers: 15)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 5)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 9)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 9)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 9)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 8)
International Journal of Space Structures     Full-text available via subscription   (Followers: 11)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 5)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 2)
International Journal of Turbo & Jet-Engines     Hybrid Journal   (Followers: 4)
Journal of Aeronautical Materials     Open Access   (Followers: 6)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 20)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 61)
Journal of Aerospace Information Systems     Full-text available via subscription   (Followers: 13)
Journal of Aerospace Technology and Management     Open Access   (Followers: 5)
Journal of Aircraft     Full-text available via subscription   (Followers: 238)
Journal of Aircraft and Spacecraft Technology     Open Access  
Journal of Airline and Airport Management     Open Access   (Followers: 8)
Journal of Astrobiology & Outreach     Open Access   (Followers: 1)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 10)
Journal of Engineering and Technological Sciences     Open Access  
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 151)
Journal of Konbin : The Journal of Air Force Institute of Technology     Open Access   (Followers: 2)
Journal of Navigation     Hybrid Journal   (Followers: 216)
Journal of Propulsion and Power     Full-text available via subscription   (Followers: 414)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 2)
Journal of Space Weather and Space Climate     Open Access   (Followers: 22)
Journal of Spacecraft and Rockets     Full-text available via subscription   (Followers: 587)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 6)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 5)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 7)
Life Sciences in Space Research     Hybrid Journal   (Followers: 2)
MAD - Magazine of Aviation Development     Open Access   (Followers: 1)
Microgravity Science and Technology     Hybrid Journal   (Followers: 1)
New Space     Hybrid Journal   (Followers: 4)
Nonlinear Dynamics     Hybrid Journal   (Followers: 16)
npj Microgravity     Open Access   (Followers: 1)
Population Space and Place     Hybrid Journal   (Followers: 6)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 1)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 10)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 42)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 75)
Propulsion and Power Research     Open Access   (Followers: 26)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 2)
RocketSTEM     Free   (Followers: 3)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 23)
Science and Education : Scientific Publication of BMSTU     Open Access  
Space and Polity     Hybrid Journal   (Followers: 4)
Space Policy     Hybrid Journal   (Followers: 26)
Space Research Today     Full-text available via subscription   (Followers: 43)
Space Safety Magazine     Free   (Followers: 44)
Space Science International     Open Access   (Followers: 141)
Space Science Reviews     Hybrid Journal   (Followers: 95)
SpaceNews     Free   (Followers: 571)
Transport and Aerospace Engineering     Open Access   (Followers: 8)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 5)
Unmanned Systems     Hybrid Journal   (Followers: 3)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 1)
Journal Cover CEAS Aeronautical Journal
  [SJR: 0.499]   [H-I: 6]   [28 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1869-5582
   Published by Springer-Verlag Homepage  [2355 journals]
  • A practical example for validation of ATM security prototypes
    • Authors: Michael Finke; Tim H. Stelkens-Kobsch
      Abstract: The insights presented in this article are outcomes of a security research project that was initiated to collate and interpret the latest findings gathered in the domain of air traffic management security. The concept of a holistic approach to security management has been evaluated. Due to the large scope of the project, only an excerpt of the findings is provided in this article. This article focuses on a brief description of a security prototype validation methodology, developed within the project. To provide tangible application of the methodology, the adoption to a security prototype is developed, which is intended to enhance security of the air traffic control voice communication system.
      PubDate: 2018-01-24
      DOI: 10.1007/s13272-017-0275-y
       
  • Evaluation of assemblability during aero engine preliminary design
    • Authors: J. Mall; S. Staudacher
      Abstract: Despite the constant growth of global air traffic, the competition amongst airlines and their aviation supply chains intensifies. In the future, stricter environmental regulations as well as economic goals will only be met by new aircrafts and aero engines. In order to evaluate the life-cycle related cost at an early stage in the product design process, it is essential to assess the manufacturability and assemblability during preliminary design. Through the assessment of assemblability, major cost drivers can be identified in order to optimize the overall production cost. In this paper, a method to assess the assemblability of different preliminary design variants is introduced. To achieve this, 2D cross sections of actual aero engines are translated into 3D preliminary design models. Finally, an evaluation of the assemblability of different design variants of low pressure turbine modules is conducted.
      PubDate: 2018-01-19
      DOI: 10.1007/s13272-017-0278-8
       
  • Comparison of sensitivities to geometrical properties of front and aft
           high pressure compressor stages
    • Authors: G. Reitz; A. Kellersmann; S. Schlange; J. Friedrichs
      Abstract: In modern aviation, the engine-related proportion of the direct operating costs (DOC) is about one quarter. Thereby, the engine-related costs are devided into three roughly equivalent parts: depreciation/financing, fuel and maintenance and overhaul (Rupp in DLRK 2001, 2001). Consequently, an efficient and high technical quality maintenance has a great impact on the DOC. Nowadays, the transition from the exhaust gas temperature based to the condition based maintenance is developing. Thereby, the maintenance, repair and overhaul (MRO) companies provide tailored maintenance actions for each jet engine, depending on the engine history and operation conditions. Obviously, a detailed knowledge of the influence of the different engine components and their features on the engine performance is necessary to accomplish a condition based maintenance. In order to illustrate this, the example of the high pressure compressor (HPC) is shown: The HPC has a strong impact on the gas turbine efficiency and the specific fuel consumption (SFC). Nevertheless, the HPC blading is classified coarsely into serviceable, scrap and repairable. The repairable blades are repaired by a few repair processes, without evaluating the blade geometry in detail. With a detailed knowledge of the geometric main parameters to the aerodynamic performance and their interactions, future repair processes could maintain suited maintenance actions as well as tailored blade sets for the HPC. Therefore, a more efficient maintenance could be achieved to meet future requirements of the costumers. This paper contributes a part to this maintenance development. Therefore, a design of experiments and a sensitivity analysis will be carried out for a HPC-aft stage and compared with previous gained results of a HPC-front stage. Therefore, 700 different stage geometries will be analyzed for their aerodynamic performance and imported to a Kriging Method to generate a meta-model. This meta-model allows a sensitivity analysis for individual geometric properties. The detected sensitivities will be compared to those of the front stage. Changes of the behavior of the stages through the HPC could help the MRO companies to focus on appropriate geometric properties and, therefore, suitable repair processes for each stage and airfoil.
      PubDate: 2018-01-18
      DOI: 10.1007/s13272-018-0281-8
       
  • In-situ structural evaluation during the fibre deposition process of
           composite manufacturing
    • Authors: F. Heinecke; T. Wille
      Abstract: Within the European funded project ECOMISE a new approach for composite manufacturing is developed. This approach provides key technologies for industry 4.0 in order to maximize process efficiency at reduced cost and time while maintaining structural requirements. In detail, process simulation methods, online process monitoring systems as well as methods for in situ structural evaluation and process adjustment in case of process deviations are implemented and linked via databases. This paper describes the new overall concept as well as the specific in situ structural evaluation approach, exemplarily applied to the fibre deposition process. Prior to manufacturing typical manufacturing features such as locally varying fibre orientation, gaps and overlaps are studied based on given knowledge from previous manufacturing as well as from process simulation. The effect of selected features on the structural properties is investigated for the expected parameter ranges. The real detected features are provided by an online monitoring system during the fibre deposition process. Based on these results an in situ structural evaluation of detected features is performed already during manufacturing in combination with a decision making with respect to required part correction. The developed key technologies and tools for the in situ evaluation process are presented, and their prototype application is shown during manufacturing of an aeronautic wing cover demonstrator.
      PubDate: 2018-01-18
      DOI: 10.1007/s13272-018-0284-5
       
  • AAA process: a new approach to affordable fly-by-wire systems for CS23
           aircraft
    • Authors: P. Mueller; T. Belschner; M. Lehmann; R. Reichel
      Abstract: LuFo IV FLYSMART and its predecessor projects succeeded in developing and integrating a full authority fly-by-wire system with ATOL capability on a DA42 of our partner Diamond Aircraft Industries. In the short term, fly-by-wire technology will open up new fields of applications for general aviation aircraft to fulfill complex mission scenarios using the Flexible Platform technology (a platform-based development approach) currently developed at the University of Stuttgart. This technology is the baseline and enables the automatization of certain certification relevant life cycle tasks, thus reducing the effort and, therefore, costs of the development. The new approach presented as following, called the AAA-Process, consists of three automatization complexes. The first complex is the automated design and documentation, the second one is the automated parameter instantiation and SW/SW–HW/SW integration and the last one is automated generation of verification artifacts. This paper introduces these automatization complexes and explains their relationship to the common life cycle process of guidance materials. The AAA-Process lays the foundation for a total system capability regarding fly-by-wire systems for the small aircraft domain while simultaneously reducing risks and costs.
      PubDate: 2018-01-15
      DOI: 10.1007/s13272-018-0282-7
       
  • Unsteady aerodynamics of a diamond wing configuration
    • Authors: Stefan Pfnür; Christian Breitsamter
      Abstract: The damping derivatives associated with the pitching, yawing, and rolling motion of the SAGITTA flying wing configuration at low Mach number conditions are presented. A tailless variant of the configuration and a variant with attached double vertical tail are investigated. The damping derivatives are determined by means of the aerodynamic response to forced harmonic oscillations. The required data for the determination of the damping derivatives are obtained from time-accurate Reynolds-averaged Navier–Stokes computations. The calculation methodology for the pitch-, yaw-, and roll-damping derivatives for arbitrary freestream conditions is described and a short evaluation of the approach is presented. Angle of attack and sideslip angle trends as well as the effect of the double vertical tail on the dynamic stability are investigated. The damping derivative of every considered type of motion exhibits significant non-linearities with respect to the freestream condition for angles of attack larger than \(8^\circ\) . The pitch-damping and roll-damping derivative indicate a dynamically stable behavior at all considered freestream conditions for the configuration with and without vertical tail. The yaw-damping characteristic is more critical. Both configurations exhibit unstable behavior at several freestream conditions. The vertical tail, however, considerably improves the yaw-damping characteristic of the SAGITTA configuration.
      PubDate: 2018-01-12
      DOI: 10.1007/s13272-018-0280-9
       
  • Support of icing flight tests by near real-time data analysis
    • Authors: Christian Raab; Per Ohme; Christoph Deiler
      Pages: 561 - 577
      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: 2017-12-01
      DOI: 10.1007/s13272-017-0260-5
      Issue No: Vol. 8, No. 4 (2017)
       
  • Future regeneration processes for high-pressure turbine blades
    • Authors: M. Nicolaus; B. Rottwinkel; I. Alfred; K. Möhwald; C. Nölke; S. Kaierle; H. J. Maier; V. Wesling
      Abstract: In this paper, new technologies for repairing turbine blades are presented, in which the manufacturing processes and materials mechanisms are incorporated. Since the turbine blades taken into consideration here are components of high pressure turbines, the focus of this paper lies on nickel-based alloys. Depending on the size and form of the defects present on the blades, two procedures can be used for repairing turbine blades: brazing and/or cladding. In one approach, a hybrid repair brazing process was developed, in which the filler metal and the hot gas corrosion protective coating were applied by thermal spraying. Subsequently, a combined brazing and aluminizing process was carried out. In a second approach, a laser cladding process for crack repair was developed wherein single crystalline solidification of the cladding material was carried out.
      PubDate: 2017-12-26
      DOI: 10.1007/s13272-017-0277-9
       
  • About the impact of wind turbine blade tip vortices on helicopter rotor
           trim and rotor blade motion
    • Authors: Berend G. van der Wall; Paul H. Lehmann
      Abstract: With increasing numbers of large wind turbines on-shore and off-shore, interactions of their wake with helicopters become a subject worth investigating. In this paper, the wake is modeled as a tip vortex helix with a vortex strength estimated from the wind turbine thrust. Helicopter rotors of different size and hub layout are subjected to the wake and the collective and cyclic control inputs required to keep the trim are compared to the maximum available control range of the rotorcraft. In addition, the blade flapping response due to the vortex influence without pilot action is computed and compared to maximum allowed flapping angles. It is found that typical on-shore wind turbines could be a hazard for ultralight helicopters, but not for larger helicopters. Large off-shore wind turbines, however, could even be a danger for small helicopters that may be used for maintenance. In addition, the results are compared to fixed-wing wake vortex interaction with a helicopter as given in the literature.
      PubDate: 2017-12-12
      DOI: 10.1007/s13272-017-0276-x
       
  • Quasi-steady doublet-lattice correction for aerodynamic gust response
           prediction in attached and separated transonic flow
    • Authors: Diliana Friedewald; Reik Thormann; Christoph Kaiser; Jens Nitzsche
      Abstract: A quasi-steady doublet-lattice correction method is used to predict aerodynamic gust responses of two different configurations: a swept wing, the so-called Aerostabil wing, and a transport aircraft configuration, the NASA Common Research Model. The results of the correction method are compared to uncorrected doublet-lattice results, and to results obtained from a nonlinear computational fluid dynamics solver, the DLR TAU-Code. The correction method agrees well with time-marching results obtained by TAU in the limit of dynamically linear gust amplitudes and improves with gust length. In separated transonic flow, an oscillation of the aerodynamic gust response can be computed.
      PubDate: 2017-11-17
      DOI: 10.1007/s13272-017-0273-0
       
  • Edge-based approach to estimate the drift of a helicopter during flight
    • Authors: Alexander Gatter
      Abstract: The Institute of Flight Systems at the German Aerospace Center (DLR) site in Braunschweig Germany has set its goal into making helicopter flying as safe as possible. The new DLR research project “Rettungshubschrauber 2030” addresses the topic of aiding helicopter rescue missions. Research will be conducted to increase the safety of these missions as well as to enable the conduct of missions in circumstances where nowadays a helicopter would not be allowed to operate. One aspect of this research is to increase or maintain the situational awareness of the pilot by processing data from camera images. The paper will focus on the field of visual odometry. It examines, if an edge-based approach for extracting features is a possible alternative or addition to established feature extractors. In the paper, two algorithms for edge extraction will be compared: an algorithm that is based on Hough transform and an algorithm that is based on the Douglas–Peucker method. They are tuned for working with images of rather low resolution and are tested on their ability to detect a sufficient amount of features in camera images as well as on their computational complexity. Then, their ability to detect the drift of a helicopter is assessed using recorded data from flight tests with the advanced control technology/flying helicopter simulator (ACT/FHS) of the DLR. Their performance will be tested on the basis of reference data from the ACT/FHS which have been recorded by the use of a highly accurate INS/DGPS system. The evaluation of the algorithms yields the result that both achieve the proposed accuracy regarding the velocity estimation with the Hough-based method achieving better accuracy while taking significantly more computational time.
      PubDate: 2017-10-27
      DOI: 10.1007/s13272-017-0270-3
       
  • Multi-use 48-kW power electronics for future aerospace applications
    • Authors: Rodolphe De Maglie; Alfred Engler; Roger Birost; Ralf Cremer
      Abstract: In the frame of the more electric aircraft and to achieve the goal of replacing hydraulic systems by electrical ones, the power density is one of the major key parameters for electrical designs. Recent advances in predevelopment activities and technologies allow today to be competitive in term of performances and weight with the existing solutions. The paper deals with the development of power electronics converter dedicated to aerospace application like environmental conditioning system and starter generator. The presented power electronic is based on a common platform where converters have been designed for ± 270 VDC network (230 VAC rectified) in duplex architecture, with and without HV input filter and inrush current limiter depending on the application. The presented GRA and SGO systems and inverters are designed and tested for flight demonstration. Descriptions of the E-ECS system and dedicated inverter are given. Many electrical (normal and abnormal steady state conditions, power input, voltage transient, etc.) and environmental (temperature, EMC, vibrations, etc.) tests according to aerospace standards are accomplished successfully: the unit shows through all these tests a high degree of maturity that is necessary to translate the research and development activities into future products. The flight test demonstration is also addressed.
      PubDate: 2017-10-23
      DOI: 10.1007/s13272-017-0268-x
       
  • Benefit evaluation of hybrid electric propulsion concepts for CS-23
           aircraft
    • Authors: M. Kreimeier; E. Stumpf
      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: 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
    • Authors: Mukesh Prasad; K. V. Gangadharan
      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: 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: 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
           blades in climb
    • Authors: Armin Weiss; Anthony D. Gardner; Christian Klein; Markus Raffel
      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: 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: 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
       
 
 
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