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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 121 journals)
Showing 1 - 30 of 30 Journals sorted by number of followers
AIAA Journal     Hybrid Journal   (Followers: 1188)
SpaceNews     Free   (Followers: 826)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 772)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 609)
Acta Astronautica     Hybrid Journal   (Followers: 493)
Advances in Space Research     Full-text available via subscription   (Followers: 458)
Aviation Week     Full-text available via subscription   (Followers: 436)
Aerospace Science and Technology     Hybrid Journal   (Followers: 428)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 384)
Journal of Aircraft     Hybrid Journal   (Followers: 335)
Control Systems     Hybrid Journal   (Followers: 314)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 278)
Journal of Navigation     Hybrid Journal   (Followers: 277)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 258)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 204)
Space Science International     Open Access   (Followers: 198)
Space Science Reviews     Hybrid Journal   (Followers: 97)
International Journal of Aerospace Engineering     Open Access   (Followers: 82)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 80)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 69)
Advances in Aerospace Engineering     Open Access   (Followers: 69)
Propulsion and Power Research     Open Access   (Followers: 68)
Aerospace     Open Access   (Followers: 60)
Space Safety Magazine     Free   (Followers: 51)
Space Research Today     Full-text available via subscription   (Followers: 48)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 46)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 40)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 39)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 37)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 34)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 34)
International Journal of Aerospace Sciences     Open Access   (Followers: 32)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 31)
Space Policy     Hybrid Journal   (Followers: 30)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 29)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 27)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 24)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 24)
Artificial Satellites     Open Access   (Followers: 23)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 23)
Annual of Navigation     Open Access   (Followers: 22)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 22)
Chinese Journal of Aeronautics     Open Access   (Followers: 21)
Nonlinear Dynamics     Hybrid Journal   (Followers: 20)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 19)
Aerospace Scientific Journal     Open Access   (Followers: 18)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 18)
Journal of Aerodynamics     Open Access   (Followers: 18)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 17)
Aviation     Open Access   (Followers: 17)
International Journal of Space Structures     Full-text available via subscription   (Followers: 17)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Fatigue of Aircraft Structures     Open Access   (Followers: 15)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
Aeronautical Journal, The     Hybrid Journal   (Followers: 12)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Journal of Airline and Airport Management     Open Access   (Followers: 12)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 12)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 11)
Air Force Magazine     Full-text available via subscription   (Followers: 11)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 11)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 11)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 10)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 10)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 9)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 9)
Journal of Aeronautical Materials     Open Access   (Followers: 9)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 9)
Population Space and Place     Hybrid Journal   (Followers: 9)
International Journal of Aviation Management     Hybrid Journal   (Followers: 9)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 8)
Air Medical Journal     Hybrid Journal   (Followers: 8)
Advances in Aerospace Science and Technology     Open Access   (Followers: 8)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 7)
Journal of Aerospace Technology and Management     Open Access   (Followers: 7)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 7)
RocketSTEM     Free   (Followers: 6)
New Space     Hybrid Journal   (Followers: 6)
Aerospace Systems     Hybrid Journal   (Followers: 6)
International Journal of Turbo and Jet-Engines     Hybrid Journal   (Followers: 6)
Unmanned Systems     Hybrid Journal   (Followers: 5)
Civil Aviation High Technologies     Open Access   (Followers: 5)
Cosmic Research     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 5)
Aviation Advances & Maintenance     Open Access   (Followers: 5)
Astrodynamics     Hybrid Journal   (Followers: 4)
Life Sciences in Space Research     Hybrid Journal   (Followers: 4)
Space and Polity     Hybrid Journal   (Followers: 4)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal   (Followers: 4)
Aerospace technic and technology     Open Access   (Followers: 3)
Investigación Pecuaria     Open Access   (Followers: 3)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
ASTRA Proceedings     Open Access   (Followers: 3)
npj Microgravity     Open Access   (Followers: 3)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Journal of KONBiN     Open Access   (Followers: 3)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Ciencia y Poder Aéreo     Open Access   (Followers: 2)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 2)
Microgravity Science and Technology     Hybrid Journal   (Followers: 2)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
MAD - Magazine of Aviation Development     Open Access   (Followers: 2)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 2)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Mekanika : Jurnal Teknik Mesin i     Open Access   (Followers: 1)
Technical Soaring     Full-text available via subscription   (Followers: 1)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Advances in Astronautics Science and Technology     Hybrid Journal   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 1)
Open Aerospace Engineering Journal     Open Access   (Followers: 1)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 1)
Perspectives of Earth and Space Scientists i     Open Access  

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Journal Cover
CEAS Aeronautical Journal
Journal Prestige (SJR): 0.248
Citation Impact (citeScore): 1
Number of Followers: 29  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1869-5582 - ISSN (Online) 1869-5590
Published by Springer-Verlag Homepage  [2652 journals]
  • Method for designing multi-input system identification signals using a
           compact time-frequency representation
    • Abstract: A flight test campaign for system identification is a costly and time-consuming task. Models derived from wind tunnel experiments and CFD calculations must be validated and/or updated with flight data to match the real aircraft stability and control characteristics. Classical maneuvers for system identification are mostly one-surface-at-a-time inputs and need to be performed several times at each flight condition. Various methods for defining very rich multi-axis maneuvers, for instance based on multisine/sum of sines signals, already exist. A new design method based on the wavelet transform allowing the definition of multi-axis inputs in the time-frequency domain has been developed. The compact representation chosen allows the user to define fairly complex maneuvers with very few parameters. This method is demonstrated using simulated flight test data from a high-quality Airbus A320 dynamic model. System identification is then performed with this data, and the results show that aerodynamic parameters can still be accurately estimated from these fairly simple multi-axis maneuvers.
      PubDate: 2021-03-12
  • Analysis of rotorcraft wind turbine wake encounters using piloted
    • Abstract: The use of offshore wind farms in Europe to provide a sustainable alternative energy source is now considered normal. Particularly in the North Sea, a large number of wind farms exist with a significant distance from the coast. This is becoming standard practice as larger areas are required to support operations. Efficient transport and monitoring of these wind farms can only be conducted using helicopters. As wind turbines continue to grow in size, there is a need to continuously update operational requirements for these helicopters, to ensure safe operations. This study assesses German regulations for flight corridors within offshore wind farms. A semi-empirical wind turbine wake model is used to generate velocity data for the research flight simulator AVES. The reference offshore wind turbine NREL 5 MW has been used and scaled to represent wind turbine of different sizes. This paper reports result from a simulation study concerning vortex wake encounter during offshore operations. The results have been obtained through piloted simulation for a transport case through a wind farm. Both subjective and objective measures are used to assess the severity of vortex wake encounters.
      PubDate: 2021-03-09
  • Analysis and design of Trajectory-Based Operations under wind forecast
    • Abstract: The Trajectory-Based Operations (TBO) concept is a key part of the FAA’s and EUROCONTROL’s programs to make flight operations more efficient and predictable, while maintaining operational flexibility. TBO relies on four-dimensional (4D) trajectories that are managed by specifying a sequence of metering points. Each metering point is associated with a controlled time of arrival (CTA) that must be met by the aircraft within a specified time tolerance. Although the TBO concept has been around for a while, prior literature has not addressed design aspects, such as identifying metering point locations and their impact on the system performance. In this paper, we show how a prior analytical model for TBO can be adapted to account for wind forecast uncertainty, and other operational constraints. We investigate the influence of different system parameters such as wind forecast uncertainty, distance between metering points, and CTA tolerance. The analysis reveals interesting trade-offs between various performance metrics such as throughput, fuel burn and delay. Based on this analysis, we propose a framework for locating metering points to satisfy traffic demand, while being fuel efficient.
      PubDate: 2021-03-06
  • Direct numerical simulation of TS-waves over suction panel steps from
           manufacturing tolerances
    • Abstract: To determine allowable tolerances between successive suction panels at hybrid laminar wings with suction surfaces, direct numerical simulations of Tollmien–Schlichting waves over different steps are carried out for realistic suction rates on a wind tunnel configuration. Simulations at given suction panel positions over forward and backward facing steps are carried out by the use of a high-order method for the direct simulation of Tollmien–Schlichting wave growth. Comparisons between high-fidelity direct numerical simulations and quick linear stability calculations have shown capabilities and limits of the well-validated linear stability theory design approach.
      PubDate: 2021-03-04
  • A completely reusable aerospace system based on subsonic carrier with the
           return of the first stages to the starting point
    • Abstract: The concept of aerospace system based on air launch from subsonic twin-fuselage aircraft and the rocket launch into orbit is investigated. The scheme of aerospace system trajectory providing a return to the starting point both of the carrier and the first rocket stage with liquid-fuel motors is proposed. It was shown that the use of subsonic carrier as a launching platform of the rocket system increases the payload mass by 1.2% of the rocket segment MTOW as compared to autonomous ground take-off. The comparative analysis of three versions of carrier aircraft and three fuel options at the first rocket stage was carried out. Analysis showed that compared to kerosene variant the hydrogen hypersonic booster makes it possible to significantly increase the payload mass while the launching costs stay the same.
      PubDate: 2021-02-23
  • Euler–Lagrangian simulation of the fuel spray of a planar prefilming
           airblast atomizer
    • Abstract: The pollutant emissions of aircraft engines are strongly affected by the fuel injection into the combustion chamber. Hence, the precise description of the fuel spray is required in order to predict these emissions more reliably. The characteristics of a spray is determined during the atomization process, especially during primary breakup in the vicinity of the atomizer nozzle. Currently, Euler-Lagrangian approaches are used to predict the droplet trajectories in combustor simulations along with reaction and pollutant formation models. To be able to reliably predict pollutant emissions in the future, well-defined starting conditions of the liquid fuel droplets close to the atomizer nozzle are necessary. In the present work, Euler-Lagrangian simulations of a generic airblast atomizer are presented. The starting conditions of the droplets are varied in the simulations by means of a primary breakup model, which takes into account the local gas velocity when predicting the droplet diameter. The objective of this work is to determine the optimal parameters of the probability density functions for the starting position and the starting velocity of the droplets. Spray properties observed in the simulations are used to qualitatively evaluate the major effects of the distribution parameters on the spray and the suitability of the primary breakup model being applied. Hence, the spatial distribution of an experimental spray can be reproduced using a statistical model for the droplet starting conditions.
      PubDate: 2021-02-21
  • Loads analysis and structural optimization of a high aspect ratio,
           composite wing aircraft
    • Abstract: Composite structures have shown a prominent impact in the aircraft structural design. With an increasing shift towards incorporating more composite materials in the primary aircraft structure it is imperative to have corresponding design tools to simplify the design process. In the present work, a simplified implementation for composite optimization has been developed within the DLR-AE (German Aerospace Centre, Institute of Aeroelasticity) automated aeroelastic structural design framework cpacs-MONA. This paper presents the results of structural optimization of a high aspect ratio composite wing aircraft model developed in the DLR project ATLAs. The generation of almost all involved simulation models for this study is done using the in-house DLR tool ModGen. An aeroelastic trim analysis is conducted for various manoeuvre and gust conditions. A load selection process is used to determine the most relevant sizing load cases. A comparison is made between the optimization results of a composite wing and an aluminium wing to demonstrate the more favourable strength to weight ratio of the composite wing. A manoeuvre load alleviation procedure has been introduced in the load calculation process. The results show further weight savings in the design process when load alleviation is utilized due to reduction in the span wise bending moment.
      PubDate: 2021-02-07
  • Load prediction of hingeless helicopter rotors including drivetrain
    • Abstract: In contrast to analyses with constrained hub speed, the present study includes the dynamic response of coupled rotor-drivetrain modes in the aeromechanic simulation of rotor blade loads. The structural model of the flexible Bo105 rotor-drivetrain system is coupled to aerodynamics modeled by an analytical formulation of unsteady blade element loads combined with a generalized dynamic wake or a free wake, respectively. For two flight states, i. e. cruise flight and large blade loading, a time-marching autopilot trim of the rotor-drivetrain system in wind tunnel configuration is performed. The simulation results are compared to those of a baseline case with constant rotor hub speed. The comparison reveals a major change in the blade passage frequency harmonics of the lead-lag loads. Beside the full drivetrain model, reduced models are shown to accurately represent the drivetrain influence on blade loads, if the eigenfrequency of the coupled second collective lead-lag/drivetrain mode is properly predicted. In a sensitivity analysis, this eigenfrequency is varied by stiffness modification of a reduced drivetrain model. The resulting changes in blade loads are correlated to this eigenfrequency, which serves as a simple though accurate classification of the drivetrain regarding its influence on vibratory blade loads. Finally, the potential to improve lead-lag load predictions by application of a drivetrain model is demonstrated through the comparison of simulated loads with measurements from a wind tunnel test.
      PubDate: 2021-02-03
  • Thank you to our CEAS Aeronautical Journal Reviewers
    • PubDate: 2021-02-01
  • Numerical investigation of the effects of fuselage upsweep in a propulsive
           fuselage concept
    • Abstract: In recent years, aircraft concepts employing wake-filling devices to reduce mission fuel burn have gained increasing attention. The study presented here aims at a detailed physical understanding of the effects of integrating a propulsive fuselage device on a commercial aircraft. Compared to an isolated, axisymmetric fuselage-propulsor configuration, a propulsive fuselage device experiences an increased circumferential inlet distortion due to three-dimensional geometric features of the aircraft. This study uses three-dimensional CFD simulations to investigate the effect of fuselage upsweep on the aero-propulsive performance of an aircraft configuration featuring a boundary layer ingestion device. It is shown that fuselage upsweep has a negative impact on the performance of a propulsive fuselage device as compared to an axisymmetric configuration. Increasing the upsweep angle by \(\Delta \alpha _{{{\text{SW}},{\text{PFC}}}} = 3.5^\circ\) leads to an increase in required fuselage fan shaft power by 19%. Furthermore, it is demonstrated that the negative effects of fuselage upsweep on the propulsor’s performance can be effectively mitigated by a circumferential variation in the propulsor nacelle thickness.
      PubDate: 2021-01-06
      DOI: 10.1007/s13272-020-00487-2
  • Estimating supersonic commercial aircraft market and resulting CO $$_2$$ 2
           emissions using public movement data
    • Abstract: Interest and effort in re-introducing civil supersonic transport (SST) airplanes as a means of travel have surged in the past decade. Current major endeavours are underway for both commercial and business supersonic vehicles. The value proposition for these aircraft exists for high-net-worth individuals and business-class travellers who value time savings more than the potential cost associated with supersonic travel. One important driver for the higher travel cost is the increase in fuel consumption for an SST due to higher cruise speeds. Even though the new SSTs in development should be more fuel-efficient than SSTs of the past, comparing to a subsonic aircraft flying the same routes, an SST that burns more fuel while having fewer passengers (pax) on board per trip yields significantly higher fuel burn per passenger for these operations. However, due to the higher ticket costs and other limitations such as noise and emissions, supersonic commercial operation is not expected to capture a large portion of the aviation market. This means that in the broader scope of global aviation, the effect of increased fuel burn per pax on fleet-level carbon dioxide (CO \(_{2}\) ) emissions is unknown. Also, due to uncertainties in the effectiveness of sonic boom reduction technologies, it remains unclear whether supersonic over-land flight will be permitted in the future. This study formulates a methodology that employs a bottom-up approach for estimating the demand for supersonic commercial operations in the coming decades, using only publicly available subsonic baseline-fleet data. The scope of this work focuses specifically on the supersonic commercial aviation market and does not consider the supersonic business jet market. The constraints and limitations identified while using publicly available data is key to understanding the data requirements for executing market assessment studies of this type. The bottom-up methodology for demand estimation is implemented, and the environmental impact of the estimated market is determined. The results identify a supersonic commercial flight demand of 34–776 daily, global flights in 2035, growing to 52–1164 in 2050, corresponding to low and high demand scenarios, respectively. These fleets will contribute approximately 1.43–28.25 megatonnes (MT) of CO \(_{2}\) to global aviation emissions in 2035, growing to 2.20–42.50 MT of CO \(_{2}\) in 2050. These emissions in 2035 and 2050 represent a 0.16–3.08% and 0.24–4.63% increase in CO \(_{2}\) emissions with respect to the 2018 global subsonic commercial aviation fleet.
      PubDate: 2021-01-04
      DOI: 10.1007/s13272-020-00486-3
  • Methods of the wall interference reduction at low supersonic velocities in
           wind tunnels
    • Abstract: The paper describes the research aimed at reducing wall interference in wind tunnels at low supersonic velocities. The results of such wind tunnel tests are often affected by wave perturbations generated by the model and reflected from the test section walls. This research describes the methods that can effectively reduce the wave reflection from the wall. A numerical investigation is presented that includes a novel boundary condition that eliminates disadvantages of previously considered methods. The numerical study was conducted in the frame of electronic wind tunnel concept and ANSYS CFX software. The numerical investigation showed that the effect of shock wave reflection could be reduced using a new type of boundary condition that is a combination of perforated walls and a controlled boundary layer.
      PubDate: 2021-01-04
      DOI: 10.1007/s13272-020-00489-0
  • CFD-based prediction of wall-pressure spectra under a turbulent boundary
           layer with adverse pressure gradient
    • Abstract: A model of the spectrum of wall-pressure fluctuations under a turbulent boundary layer based on an analytical solution of the Poisson equation is presented. This model is suited for aeroacoustic prediction based on CFD-extracted flow information but requires statistical properties of the boundary-layer turbulence that are not resolved in steady-state simulations and need to be modelled. For this reason, this paper uses Lattice-Boltzmann (DNS-LBM) and Navier-Stokes Direct Numerical Simulations (DNS-NS) of an airfoil in a wind-tunnel jet to investigate the link between turbulence and wall-pressure statistics and validate the assumptions made in the application of the analytical model. The use of input from two numerical simulation methods allows generalizing the results of the analytical model.
      PubDate: 2021-01-04
      DOI: 10.1007/s13272-020-00484-5
  • Increasing helicopter flight safety in maritime operations with a
           head-mounted display
    • Abstract: To increase flight safety and operational availability for helicopters, the potential benefits of helmet-mounted displays (HMD) are investigated, with a focus on maritime flight operations. Helicopters have long downtimes, due to harsh weather conditions or other visual impairments, especially in maritime scenarios. Flying in these poor conditions can drastically reduce flight safety. It is often difficult to recognize the horizon due to sea fog, and the absence of reference objects can complicate the maritime flight. These conditions and especially the downtimes cost money or, at worst, life’s. Therefore, DLR integrated the augmented reality glasses Microsoft HoloLens into DLR’s simulator AVES to use it as HMD for pilots. Subsequently, displays and symbology were developed and evaluated. To carry out a piloted simulator study, a maritime scenario was created to measure changes in the pilots’ performance with the HMD, like workload or situational awareness. The paper focuses (a) on the integration of the HoloLens into the simulator with its challenges, solutions and findings, (b) on the symbology and (c) on the piloted simulator study. Both the quality of the HoloLens as HMD and the study results are very positive. The pilots rated high usability, reduced workload, increased situational awareness and increased safety.
      PubDate: 2021-01-01
  • Co-design of aircraft vertical tail and control laws with distributed
           electric propulsion and flight envelop constraints
    • Abstract: A sequential co-design framework has been developed in a previous study (Nguyen-Van et al., IFAC-PapersOnLine 52(12):514–519, https://doi.org/10.1016/j.ifacol.2019.11.295, 2019)) to design an aircraft using active differential thrust. Differential thrust is used instead of a rudder to generate the yawing moment. The objective is to dimension in parallel the vertical tail surface area, the electric motor bandwidth and control laws while maintaining imposed handling qualities. This paper focuses on the development of a single step co-design taking into account handling qualities, flight envelop requirements and motor saturation. Additional and compatible optimisation constraints are found based on a sensitivity analysis. It reveals the importance of electric motor bandwidth with respect to aircraft natural stability. The direct co-design leads to an optimised trade-off between vertical tail and electric motor bandwidth.
      PubDate: 2021-01-01
  • Linearly variable chord-extension morphing for helicopter rotor blades
    • Abstract: A new morphing concept called linearly variable chord extension was studied for its effectiveness in improving the efficiency of a helicopter rotor. Apart from chord extension itself, an additional feature which is deflection of the extended part of the chord resulting in an effective camber and additional twist to the airfoil, is also studied for its effect on rotor efficiency improvement. Trim analyses were carried out for various chord-extended rotors for hover as well as various forward flight velocities using DLR’s in-house comprehensive analysis code S4. Chord extension of up to 100% and chord-extension–deflection of up to 15° were considered. Results show that the linearly variable chord-extension concept is effective in reducing power requirement in both hover and forward flight. Deflection of the extended chord also helps reduce power requirement in hover, especially at higher blade loadings. However, the root torsional moments and hence, the pitch-link loads are seen to increase substantially for the morphed rotors.
      PubDate: 2021-01-01
  • Maritime operation of an unmanned rotorcraft with tethered ship deck
           landing system
    • Abstract: In security-critical situations in the maritime area, ship-based deployment of remotely piloted aircraft systems could enable automated acquisition of aerial images and other sensor data. If intervention is required, response times of federal institutions could be shortened significantly without endangering personnel. This paper gives an overview of research undertaken at DLR in cooperation with the German Federal Police for Maritime Tasks. For a safe ship deck landing of an unmanned rotorcraft a combination of precise navigation and tethered landing system has been developed and patented. Relative double-difference algorithms are used for precise navigation of the rotorcraft to a hover point over the ship deck. From there, an electromagnetic winch is lowered from the rotorcraft that connects to the ship deck. The resulting cable connection is used for aligning the rotorcraft during landing and securing it on the ship deck afterwards. First demonstrations on a real ship deck show the feasibility of the system.
      PubDate: 2021-01-01
  • Autonomous trajectory tracking of a quadrotor UAV using ANFIS controller
           based on Gaussian pigeon-inspired optimization
    • Abstract: This paper develops a method to tune neuro-fuzzy controllers using metaheuristic optimization. The main purpose of this approach is that it allows neuro-fuzzy controllers to be tuned to achieve global performance requirements. This paper proposes a robust and intelligent control method based on adaptive neuro-fuzzy inference system (ANFIS) and pigeon-inspired optimization (PIO) algorithm to govern the behavior of a three-degree-of-freedom (3-DOF) quadrotor unmanned aerial vehicle (UAV). UAVs are flying platforms that have become increasingly used in a wide range of applications. However, the most recent research has aimed to improve the quality of UAVs control in order to achieve its mission accurately. The quadrotor is chosen due to its simple mechanical structure; nevertheless, these types of UAVs are highly nonlinear. Intelligent control that uses artificial intelligence approach such as fuzzy logic is a suitable choice to better control nonlinear systems. The ANFIS controller is proposed to control the movement of UAV to track a given reference trajectory in 2-D vertical plane. The PIO is used to obtain the ANFIS optimal parameters with the aim of improving the quality of the controller and, therefore, to minimize tracking error. To evaluate the performance of the ANFIS-PIO, a comparison between the proposed controller, ANFIS and proportional–integral–derivative (PID) controllers is illustrated. The results demonstrate that the proposed controller is more effective compared to the other controllers.
      PubDate: 2021-01-01
  • Investigation of the sooting propensity of aviation fuel mixtures
    • Abstract: Aromatic compounds occurring naturally in jet fuels are precursors for the formation of soot in the exhaust gas of jet engines. Directly emitted in cruising altitude, soot particles lead to the formation of contrails and clouds influencing the radiation balance of the atmosphere. Hence, a detailed knowledge on the effect of aromatics on the sooting behavior is of great importance, especially for the development of alternative synthetic jet fuels. Investigations on the sooting propensity influenced by the molecular structure and concentration of diverse aromatic compounds contained in synthetic and fossil aviation fuels as well as blends of synthetic paraffinic kerosene (SPK) with aromatic compounds (SKA) were carried out experimentally. Using a predefined SPK fuel, five different blends—each containing a single aromatic compound—were prepared in addition to one blend with a typical composition consisting of all these aromatic compounds. In subsequent measurements, the concentration of the aromatics was increased from initially 8.0 vol%, to about 16.5, and 25.0 vol%. The aromatics added were toluene, n­-propylbenzene, indane, 1­methylnaphthalene, and biphenyl. The studied jet fuels include fossil-based Jet A-1 as well as different synthetic jet fuels (with and without aromatics). Furthermore, the experimental results of the sooting propensity are compared with the results of the hydrogen deficiency model being a measure for the amount of cyclic and unsaturated molecular structures occurring in a hydrocarbon fuel. This study shows the hydrogen deficiency as a useful tool to make predictions about the sooting behavior of different fuels compared to a reference fuel at a specified condition. Additionally, it is observed from the measured sooting propensities as well as from the model predictions of hydrogen deficiency that the structure of aromatic compounds presents greater influence on the soot formation than the aromatic concentration.
      PubDate: 2021-01-01
  • Numerical position optimization of an over-the-wing mounted engine
    • Abstract: The Collaborative Research Center 880 is investigating different technologies and configurative variants for the purpose of short take-off and landing (STOL) capabilities, ranging from high-lift systems with Coandӑ flaps to unusual but potentially more efficient engine arrangements. The present study focuses on the reference configuration 3 (REF3). This configuration is characterized by an UHBR over-the-wing nacelle (OWN) located above the wing trailing edge. Starting from the wing/body configuration the installation effects of the OWN were investigated. A fully automatized surrogate based optimization was used to evaluate the impact of an engine position variation in vertical and horizontal direction to observe fundamental aerodynamic interactions between wing and OWN in cruise flight conditions. Due to the presence of OWN and pylon, a distinct disturbance on the wing upper surface could be observed leading to significant interference effects. Nevertheless, the overall cruise drag of REF3 could be improved by 37 drag counts or nearly 11% due to the position optimization.
      PubDate: 2020-12-23
      DOI: 10.1007/s13272-020-00485-4
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