TY  - CHAP
A1  - Otten, D.
A1  - Schmidt, M.
A1  - Weber, Tobias
T1  - Advances in Determination of Material Parameters for Functional Simulations Based on Process Simulations
T2  - SAMPE Europe Conference 16 Liege
Y1  - 2016
SN  - 978-1-5108-3800-0
SP  - 570
EP  - 577
ER  - 
TY  - CHAP
A1  - Otten, D.
A1  - Schmid, M.
A1  - Weber, Tobias
T1  - Advances In Sheet Metal-Forming: Reduction Of Tooling Cost By Methodical Optimization
T2  - Proceedings of SAMPE Europe Conference, Amiens , France
Y1  - 2015
ER  - 
TY  - CHAP
A1  - Olaru, Alexandra Maria
A1  - Kowalski, Julia
A1  - Sethi, Vaishali
A1  - Blümich, Bernhard
T1  - Fluid Transport in Porous Media probed by Relaxation-Exchange NMR
T2  - 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.
Y1  - 2011
N1  - H12B-07; American Geophysical Union
ER  - 
TY  - CHAP
A1  - Ohndorf, Andreas
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
A1  - Schartner, Karl-Heinz
T1  - Flight times to the heliopause using a combination of solar and radioisotope electric propulsion
T2  - 32nd International Electric Propulsion Conference
N2  - We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks’ parameter set. Based on a parameter space study, in which the number of thrust units, the unit’s specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically
more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every
year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the
escape direction is restricted to the heliosphere’s “nose".
KW  - low-thrust trajectory optimization
KW  - heliosphere
KW  - ion propulsion
Y1  - 2011
N1  - IEPC-2011-051
32nd International Electric Propulsion Conference,September 11–15, 2011
Wiesbaden, Germany
SP  - 1
EP  - 12
ER  - 
TY  - CHAP
A1  - Nowack, N.
A1  - Röth, Thilo
A1  - Bührig-Polaczek, A.
A1  - Klaus, G.
ED  - Hirsch, Jürgen
T1  - Advanced Sheet Metal Components Reinforced by Light Metal Cast Structures
T2  - Aluminium alloys : their physical and mechanical properties ; [proceedings of the 11th International Conference on Aluminium Alloys, 22 - 26 Sept. 2008, Aachen, Germany ; ICAA 11]
Y1  - 2008
SN  - 978-3-527-32367-8
IS  - 2
SP  - 2374
EP  - 2381
ER  - 
TY  - CHAP
A1  - Niedermeier, H.
A1  - Clemens, J.
A1  - Kowalski, Julia
A1  - Macht, S.
A1  - Heinen, D.
A1  - Hoffmann, R.
A1  - Linder, Peter
T1  - Navigation system for a research ice probe for antarctic glaciers
T2  - IEEE/ION Position, Location and Navigation Symposium (PLANS) ; 5-8 May 2014, Monterey, Calif.
Y1  - 2014
SN  - 978-1-4799-3319-8
SP  - 959
EP  - 975
PB  - IEEE
CY  - Piscataway, NJ
ER  - 
TY  - CHAP
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - Operational modal analysis of a cantilever in a wind tunnel using optical fiber bragg grating sensors
T2  - 6th International Operational Modal Analysis Conference. IOMAC´15. 2015 May 12-14 Gijon - Spain
Y1  - 2015
U6  - https://doi.org/10.13140/RG.2.1.3753.0324
ER  - 
TY  - CHAP
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - In-flight vibration-based structural health monitoring of aircraft wings
T2  - 30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea
N2  - This work presents a methodology for automated
damage-sensitive feature extraction and anomaly
detection under multivariate operational variability
for in-flight assessment of wings. The
method uses a passive excitation approach, i. e.
without the need for artificial actuation. The
modal system properties (natural frequencies and
damping ratios) are used as damage-sensitive
features. Special emphasis is placed on the use
of Fiber Bragg Grating (FBG) sensing technology
and the consideration of Operational and
Environmental Variability (OEV). Measurements
from a wind tunnel investigation with a composite
cantilever equipped with FBG and piezoelectric
sensors are used to successfully detect an impact
damage. In addition, the feasibility of damage
localisation and severity estimation is evaluated
based on the coupling found between damageand
OEV-induced feature changes.
Y1  - 2016
ER  - 
TY  - CHAP
A1  - Möhren, Felix
A1  - Bergmann, Ole
A1  - Janser, Frank
A1  - Braun, Carsten
T1  - On the determination of harmonic propeller loads
T2  - AIAA SCITECH 2023 Forum
N2  - Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures.
Y1  - 2023
U6  - https://doi.org/10.2514/6.2023-2404
N1  - AIAA SCITECH 2023 Forum, 23-27 January 2023, National Harbor, Md & Online
PB  - AIAA
ER  - 
TY  - CHAP
A1  - Mulsow, Niklas A.
A1  - Hülsen, Benjamin
A1  - Gützlaff, Joel
A1  - Spies, Leon
A1  - Bresser, Andreas
A1  - Dabrowski, Adam
A1  - Czupalla, Markus
A1  - Kirchner, Frank
T1  - Concept and design of an autonomous micro rover for long term lunar exploration
T2  - Proceedings of the 74th International Astronautical Congress
N2  - Research on robotic lunar exploration has seen a broad revival, especially since the Google Lunar X-Prize increasingly brought private endeavors into play. This development is supported by national agencies with the aim of enabling long-term lunar infrastructure for in-situ operations and the establishment of a moon village. One challenge for effective exploration missions is developing a compact and lightweight robotic rover to reduce launch costs and open the possibility for secondary payload options. Existing micro rovers for exploration missions are clearly limited by their design for one day of sunlight and their low level of autonomy. For expanding the potential mission applications and range of use, an extension of lifetime could be reached by surviving the lunar night and providing a higher level of autonomy. To address this objective, the paper presents a system design concept for a lightweight micro rover with long-term mission duration capabilities, derived from a multi-day lunar mission scenario at equatorial regions. Technical solution approaches are described, analyzed, and evaluated, with emphasis put on the harmonization of hardware selection due to a strictly limited budget in dimensions and power.
Y1  - 2023
N1  - 74. International Astronautical Congress (IAC-2023), October 2-6 2023, Baku, Azerbaijan
PB  - dfki
CY  - Saarbrücken
ER  - 
TY  - CHAP
A1  - Mertens, Josef
T1  - Laminar leading edges: manufacturing, contamination, and operational aspects - results from the German RaWid programme
N2  - RaWid was the German national technology programme on transonic aerodynamics and supporting technologies, lasting from 1995 to 1998. One of the main topics was laminar wing development. Besides aerodynamic design work, many operational aspects were investigated. A manufacturing concept was developed to be applied to operational laminar wings and empennages. It was built in a large scale manufacturing demonstrator with the aerodynamic shape of a 1,5 m section of the A320 fin nose. Tolerances in shape and roughness fulfilled all requirements. The construction can easily be adapted to varying stiffness and strength requirements. Weight and manufacturing costs are comparable to common nose designs. The mock-up to be designed in ALTTA is based on this manufacturing principle. Another critical point is contamination of suction surfaces. Several tests were performed to investigate perforated titanium suction surfaces at realistic operational conditions: - a one year flight test with a suction plate in the stagnation area of the Airbus "Beluga" - a one year test of several suction plates in a ground test near the airport - a one year test of a working suction ground test installation at all weather conditions. No critical results were found. There is no long term suction degradation visible. Icing conditions and ground de-icing fluids used on airports did not pose severe problems. Some problems detected require only respection of weak design constraints.
KW  - Laminare Strömung
KW  - Ansaugsystem
KW  - Profilumströmung
KW  - Laminarprofil
KW  - RaWid
KW  - hybrid laminar flow
KW  - suction systems
KW  - suction structure
KW  - contamination
KW  - operational aspects
Y1  - 2000
ER  - 
TY  - CHAP
A1  - Mertens, Josef
T1  - Next steps envisaged to improve wing performance of commercial aircraft
T2  - Aerodynamic drag reduction technologies : proceedings of the CEAS/DragNet European Drag Reduction Conference, 19–21 June 2000, Potsdam, Germany. - (Notes on numerical fluid mechanics ; 76)
Y1  - 2001
SN  - 3-540-41911-X (Print)
SN  - 978-3-540-45359-8 (Elektronisch)
U6  - https://doi.org/10.1007/978-3-540-45359-8_26
SP  - 246
EP  - 255
PB  - Springer
CY  - Berlin [u.a.]
ER  - 
TY  - CHAP
A1  - Mertens, Josef
ED  - Nitsche, Wolfgang
T1  - Some important results of the technology programme RaWid
T2  - New Results in Numerical and Experimental Fluid Mechanics : Contributions to the 11th AG STAB/DGLR Symposium Berlin, Germany 1998. - Vol. 2. - (Notes on Numerical Fluid Mechanics ; 72)
Y1  - 1999
SN  - 978-3-663-10903-7 (Print)
SN  - 978-3-663-10901-3 (Elektronisch)
U6  - https://doi.org/10.1007/978-3-663-10901-3_41
SP  - 315
EP  - 322
PB  - Springer Fachmedien
CY  - Wiesbaden
ER  - 
TY  - CHAP
A1  - Mayntz, Joscha
A1  - Keimer, Jona
A1  - Dahmann, Peter
A1  - Hille, Sebastian
A1  - Stumpf, Eike
A1  - Fisher, Alex
A1  - Dorrington, Graham
T1  - Electrical Drive and Regeneration in General Aviation Flight with Propellers
T2  - Deutscher Luft- und Raumfahrtkongress 2020
N2  - Electric flight has the potential for a more sustainable and energy-saving way of aviation compared to fossil fuel aviation. The electric motor can be used as a generator inflight to regenerate energy during descent. Three different approaches to regenerating with electric propeller powertrains are proposed in this paper. The powertrain is to be set up in a wind tunnel to determine the propeller efficiency in both working modes as well as the noise emissions. Furthermore, the planned flight tests are discussed. In preparation for these tests, a yaw stability analysis is performed with the result that the aeroplane is controllable during flight and in the most critical failure case. The paper shows the potential for inflight regeneration and addresses the research gaps in the dual role of electric powertrains for propulsion and regeneration of general aviation aircraft.
KW  - Propeller Aerodynamics
KW  - Flight Tests
KW  - Flight Mechanics
KW  - Electrical Flight
KW  - Inflight Regeneration, Recuperation
Y1  - 2022
U6  - https://doi.org/10.25967/530100
N1  - Deutscher Luft- und Raumfahrtkongress 2020, 1. - 3. September 2020, Online
PB  - DGLR
CY  - Bonn
ER  - 
TY  - CHAP
A1  - Mathiak, Gerhard
A1  - Plescher, Engelbert
A1  - Willnecker, Rainer
T1  - Parabolic flight experiments about vibrational effects on diffusion experiments
T2  - 54th International Astronautical Congress of the International Astronautical Federation (IAF) :  Bremen, 29 Sept. 2003 through 3 Oct. 2003 ; vol. 1
Y1  - 2003
SP  - 4389
EP  - 4396
ER  - 
TY  - CHAP
A1  - Ludowicy, Jonas
A1  - Rings, René
A1  - Finger, Felix
A1  - Braun, Carsten
A1  - Bil, Cees
T1  - Impact of Propulsion Technology Levels on the Sizing and Energy Consumption for Serial HybridElectric General Aviation Aircraft
T2  - Asia Pacific International Symposium on Aerospace Technology. APISAT 2019
Y1  - 2019
ER  - 
TY  - CHAP
A1  - Ludowicy, Jonas
A1  - Rings, René
A1  - Finger, Felix
A1  - Braun, Carsten
T1  - Sizing Studies of Light Aircraft with Serial Hybrid Propulsion Systems
T2  - Luft- und Raumfahrt - Digitalisierung und Vernetzung : Deutscher Luft- und Raumfahrtkongress 2018. 4. - 6. September 2018 - Friedrichshafen
Y1  - 2018
ER  - 
TY  - CHAP
A1  - Ludowicy, Jonas
A1  - Rings, René
A1  - Finger, Felix
A1  - Braun, Carsten
T1  - Sizing Studies of Light Aircraft with Parallel Hybrid Propulsion Systems
T2  - Deutscher Luft- und Raumfahrtkongress 2018
Y1  - 2018
U6  - https://doi.org/10.25967/480227
ER  - 
TY  - CHAP
A1  - Loeb, Horst Wolfgang
A1  - Schartner, Karl-Heinz
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
T1  - SEP-Sample return from a main belt asteroid
T2  - 30th International Electric Propulsion Conference
N2  - By DLR-contact, sample return missions to the large main-belt asteroid “19, Fortuna” have been studied. The mission scenario has been based on three ion thrusters of the RIT-22 model, which is presently under space qualification, and on solar arrays equipped with triple-junction GaAs solar cells. After having designed the spacecraft, the orbit-to-orbit trajectories for both, a one-way SEP mission with a chemical sample return and an all-SEP return mission, have been optimized using a combination of artificial neural networks with evolutionary algorithms. Additionally, body-to-body trajectories have been
investigated within a launch period between 2012 and 2015. For orbit-to-orbit calculation, the launch masses of the hybrid mission and of the all-SEP mission resulted in 2.05 tons and 1.56 tons, respectively, including a scientific payload of 246 kg. For the related transfer
durations 4.14 yrs and 4.62 yrs were obtained. Finally, a comparison between the mission scenarios based on SEP and on NEP have been carried out favouring clearly SEP.
Y1  - 2007
SP  - 1
EP  - 11
ER  - 
TY  - CHAP
A1  - Loeb, Horst W.
A1  - Schartner, Karl-Heinz
A1  - Seboldt, Wolfgang
A1  - Dachwald, Bernd
A1  - Streppel, Joern
A1  - Meusemann, Hans
A1  - Schülke, Peter
T1  - SEP for a lander mission to the jovian moon europa
T2  - 57th International Astronautical Congress
N2  - Under DLR-contract, Giessen University and DLR Cologne are studying solar-electric propulsion missions (SEP) to the outer regions of the solar system. The most challenging reference mission concerns the transport of a 1.35-tons chemical lander spacecraft into an 80-RJ circular orbit around Jupiter, which would enable to place a 375 kg lander with 50 kg of scientific instruments on the surface of the icy moon "Europa". Thorough analyses show that the best solution in terms of SEP launch mass times thrusting time would be a two-stage EP module and a triple-junction solar array with concentrators which would be deployed step by step. Mission performance optimizations suggest to propel the spacecraft in the first EP stage by 6 gridded ion thrusters, running at 4.0 kV of beam voltage, which would save launch mass, and in the second stage by 4 thrusters with 1.25 to 1.5 kV of positive high voltage saving thrusting time. In this way, the launch mass of the spacecraft would be kept within 5.3 tons. Without a launcher's C3 and interplanetary gravity assists, Jupiter might be reached within about 4 yrs. The spiraling-down into the parking orbit would need another 1.8 yrs. This "large mission" can be scaled down to a smaller one, e.g., by halving all masses, the solar array power, and the number of thrusters. Due to their reliability, long lifetime and easy control, RIT-22 engines have been chosen for mission analysis. Based on precise tests, the thruster performance has been modeled.
Y1  - 2006
U6  - https://doi.org/10.2514/6.IAC-06-C4.4.04
N1  - 57th International Astronautical Congress, 02 October 2006 - 06 October 2006, Valencia, Spain.
SP  - 1
EP  - 12
ER  -