@article{GoettenFingerHavermannetal.2021,
  author    = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Marino, M. and Bil, C.},
  title     = {Full configuration drag estimation of short-to-medium range fixed-wing UAVs and its impact on initial sizing optimization},
  series = {CEAS Aeronautical Journal},
  volume    = {12},
  journal   = {CEAS Aeronautical Journal},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1869-5590 (Online)},
  doi       = {10.1007/s13272-021-00522-w},
  pages     = {589 -- 603},
  year      = {2021},
  abstract  = {The paper presents the derivation of a new equivalent skin friction coefficient for estimating the parasitic drag of short-to-medium range fixed-wing unmanned aircraft. The new coefficient is derived from an aerodynamic analysis of ten different unmanned aircraft used for surveillance, reconnaissance, and search and rescue missions. The aircraft is simulated using a validated unsteady Reynolds-averaged Navier Stokes approach. The UAV's parasitic drag is significantly influenced by the presence of miscellaneous components like fixed landing gears or electro-optical sensor turrets. These components are responsible for almost half of an unmanned aircraft's total parasitic drag. The new equivalent skin friction coefficient accounts for these effects and is significantly higher compared to other aircraft categories. It is used to initially size an unmanned aircraft for a typical reconnaissance mission. The improved parasitic drag estimation yields a much heavier unmanned aircraft when compared to the sizing results using available drag data of manned aircraft.},
  language  = {en}
}
@article{GoettenFingerHavermannetal.2018,
  author    = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bill, C.},
  title     = {On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles},
  series = {Deutscher Luft- und Raumfahrtkongress 2018},
  journal   = {Deutscher Luft- und Raumfahrtkongress 2018},
  publisher = {DGLR},
  address   = {Bonn},
  doi       = {10.25967/480058},
  pages     = {11 S.},
  year      = {2018},
  abstract  = {The flight performance impact of three different landing gear configurations on a small, fixed-wing UAV is analyzed with a combination of RANS CFD calculations and an incremental flight performance algorithm. A standard fixed landing gear configuration is taken as a baseline, while the influence of retracting the landing gear or applying streamlined fairings is investigated. A retraction leads to a significant parasite drag reduction, while also fairings promise large savings. The increase in lift-to-drag ratio is reduced at high lift coefficients due to the influence of induced drag. All configurations are tested on three different design missions with an incremental flight performance algorithm. A trade-off study is performed using the retracted or faired landing gear's weight increase as a variable. The analysis reveals only small mission performance gains as the aerodynamic improvements are negated by weight penalties. A new workflow for decision-making is presented that allows to estimate if a change in landing gear configuration is beneficial for a small UAV.},
  language  = {en}
}
@inproceedings{GoettenFingerBraunetal.2019,
  author    = {G{\"o}tten, Falk and Finger, Felix and Braun, Carsten and Havermann, Marc and Bil, C. and Gomez, F.},
  title     = {Empirical Correlations for Geometry Build-Up of Fixed Wing Unmanned Air Vehicles},
  series = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)},
  booktitle = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)},
  publisher = {Springer},
  address   = {Singapore},
  isbn      = {978-981-13-3305-7},
  doi       = {10.1007/978-981-13-3305-7_109},
  pages     = {1365 -- 1381},
  year      = {2019},
  abstract  = {The results of a statistical investigation of 42 fixed-wing, small to medium sized (20 kg-1000 kg) reconnaissance unmanned air vehicles (UAVs) are presented. Regression analyses are used to identify correlations of the most relevant geometry dimensions with the UAV's maximum take-off mass. The findings allow an empirical based geometry-build up for a complete unmanned aircraft by referring to its take-off mass only. This provides a bridge between very early design stages (initial sizing) and the later determination of shapes and dimensions. The correlations might be integrated into a UAV sizing environment and allow designers to implement more sophisticated drag and weight estimation methods in this process. Additional information on correlation factors for a rough drag estimation methodology indicate how this technique can significantly enhance the accuracy of early design iterations.},
  language  = {en}
}
@inproceedings{FingerKhalsaKreyeretal.2019,
  author    = {Finger, Felix and Khalsa, R. and Kreyer, J{\"o}rg and Mayntz, Joscha and Braun, Carsten and Dahmann, Peter and Esch, Thomas and Kemper, Hans and Schmitz, O. and Bragard, Michael},
  title     = {An approach to propulsion system modelling for the conceptual design of hybrid-electric general aviation aircraft},
  series = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt},
  booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt},
  pages     = {15 Seiten},
  year      = {2019},
  abstract  = {In this paper, an approach to propulsion system modelling for hybrid-electric general aviation aircraft is presented. Because the focus is on general aviation aircraft, only combinations of electric motors and reciprocating combustion engines are explored. Gas turbine hybrids will not be considered. The level of the component's models is appropriate for the conceptual design stage. They are simple and adaptable, so that a wide range of designs with morphologically different propulsive system architectures can be quickly compared. Modelling strategies for both mass and efficiency of each part of the propulsion system (engine, motor, battery and propeller) will be presented.},
  language  = {en}
}
@inproceedings{FingerGoettenBraunetal.2019,
  author    = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees},
  title     = {Mass, Primary Energy, and Cost - The Impact of Optimization Objectives on the Initial Sizing of Hybrid-Electric General Aviation Aircraft},
  series = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany},
  booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany},
  doi       = {10.25967/490012},
  pages     = {1 -- 17},
  year      = {2019},
  language  = {en}
}
@article{FingerGoettenBraunetal.2020,
  author    = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees},
  title     = {Mass, primary energy, and cost: the impact of optimization objectives on the initial sizing of hybrid-electric general aviation aircraft},
  series = {CEAS Aeronautical Journal},
  volume    = {2020},
  journal   = {CEAS Aeronautical Journal},
  number    = {11},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {1869-5590},
  doi       = {10.1007/s13272-020-00449-8},
  pages     = {713 -- 730},
  year      = {2020},
  abstract  = {For short take-off and landing (STOL) aircraft, a parallel hybrid-electric propulsion system potentially offers superior performance compared to a conventional propulsion system, because the short-take-off power requirement is much higher than the cruise power requirement. This power-matching problem can be solved with a balanced hybrid propulsion system. However, there is a trade-off between wing loading, power loading, the level of hybridization, as well as range and take-off distance. An optimization method can vary design variables in such a way that a minimum of a particular objective is attained. In this paper, a comparison between the optimization results for minimum mass, minimum consumed primary energy, and minimum cost is conducted. A new initial sizing algorithm for general aviation aircraft with hybrid-electric propulsion systems is applied. This initial sizing methodology covers point performance, mission performance analysis, the weight estimation process, and cost estimation. The methodology is applied to the design of a STOL general aviation aircraft, intended for on-demand air mobility operations. The aircraft is sized to carry eight passengers over a distance of 500 km, while able to take off and land from short airstrips. Results indicate that parallel hybrid-electric propulsion systems must be considered for future STOL aircraft.},
  language  = {en}
}
@inproceedings{FingerGoettenBraunetal.2019,
  author    = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees},
  title     = {Cost Estimation Methods for Hybrid-Electric General Aviation Aircraft},
  series = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019},
  booktitle = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019},
  pages     = {1 -- 13},
  year      = {2019},
  language  = {en}
}
@inproceedings{FingerGoettenBraunetal.2019,
  author    = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, C.},
  title     = {On Aircraft Design Under the Consideration of Hybrid-Electric Propulsion Systems},
  series = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)},
  booktitle = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)},
  publisher = {Springer},
  address   = {Singapore},
  isbn      = {978-981-13-3305-7},
  doi       = {10.1007/978-981-13-3305-7_99},
  pages     = {1261 -- 1272},
  year      = {2019},
  abstract  = {A hybrid-electric propulsion system combines the advantages of fuel-based systems and battery powered systems and offers new design freedom. To take full advantage of this technology, aircraft designers must be aware of its key differences, compared to conventional, carbon-fuel based, propulsion systems. This paper gives an overview of the challenges and potential benefits associated with the design of aircraft that use hybrid-electric propulsion systems. It offers an introduction of the most popular hybrid-electric propulsion architectures and critically assess them against the conventional and fully electric propulsion configurations. The effects on operational aspects and design aspects are covered. Special consideration is given to the application of hybrid-electric propulsion technology to both unmanned and vertical take-off and landing aircraft. The authors conclude that electric propulsion technology has the potential to revolutionize aircraft design. However, new and innovative methods must be researched, to realize the full benefit of the technology.},
  language  = {en}
}
@inproceedings{FingerGoettenBraun2018,
  author    = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten},
  title     = {Initial Sizing for a Family of Hybrid-Electric VTOL General Aviation Aircraft},
  series = {67. Deutscher Luft- und Raumfahrtkongress 2018},
  booktitle = {67. Deutscher Luft- und Raumfahrtkongress 2018},
  pages     = {14 S.},
  year      = {2018},
  language  = {en}
}
@inproceedings{FingerdeVriesVosetal.2020,
  author    = {Finger, Felix and de Vries, Reynard and Vos, Roelof and Braun, Carsten and Bil, Cees},
  title     = {A comparison of hybrid-electric aircraft sizing methods},
  series = {AIAA Scitech 2020 Forum},
  booktitle = {AIAA Scitech 2020 Forum},
  doi       = {10.2514/6.2020-1006},
  pages     = {31 Seiten},
  year      = {2020},
  language  = {en}
}
@inproceedings{FingerBraunBil2018,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Case studies in initial sizing for hybrid-electric general aviation aircraft},
  series = {2018 AIAA/IEEE Electric Aircraft Technologies Symposium, Cincinnati, Ohio},
  booktitle = {2018 AIAA/IEEE Electric Aircraft Technologies Symposium, Cincinnati, Ohio},
  doi       = {10.2514/6.2018-5005},
  year      = {2018},
  language  = {en}
}
@article{FingerBraunBil2018,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Impact of electric propulsion technology and mission requirements on the performance of VTOL UAVs},
  series = {CEAS Aeronautical Journal},
  volume    = {10},
  journal   = {CEAS Aeronautical Journal},
  number    = {3},
  publisher = {Springer},
  issn      = {1869-5582 print},
  doi       = {10.1007/s13272-018-0352-x},
  pages     = {843},
  year      = {2018},
  abstract  = {One of the engineering challenges in aviation is the design of transitioning vertical take-off and landing (VTOL) aircraft. Thrust-borne flight implies a higher mass fraction of the propulsion system, as well as much increased energy consumption in the take-off and landing phases. This mass increase is typically higher for aircraft with a separate lift propulsion system than for aircraft that use the cruise propulsion system to support a dedicated lift system. However, for a cost-benefit trade study, it is necessary to quantify the impact the VTOL requirement and propulsion configuration has on aircraft mass and size. For this reason, sizing studies are conducted. This paper explores the impact of considering a supplemental electric propulsion system for achieving hovering flight. Key variables in this study, apart from the lift system configuration, are the rotor disk loading and hover flight time, as well as the electrical systems technology level for both batteries and motors. Payload and endurance are typically used as the measures of merit for unmanned aircraft that carry electro-optical sensors, and therefore the analysis focuses on these particular parameters.},
  language  = {en}
}
@inproceedings{FingerBraunBil2017,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {The Impact of Electric Propulsion on the Performance of VTOL UAVs},
  series = {Deutscher Luft- und Raumfahrtkongress 2017, DLRK , M{\"u}nchen},
  booktitle = {Deutscher Luft- und Raumfahrtkongress 2017, DLRK , M{\"u}nchen},
  year      = {2017},
  language  = {en}
}
@inproceedings{FingerBraunBil2017,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {A Review of Configuration Design for Distributed Propulsion Transitioning VTOL Aircraft},
  series = {Asia-Pacific International Symposium on Aerospace Technology 2017, APISAT 2017, Seoul, Korea},
  booktitle = {Asia-Pacific International Symposium on Aerospace Technology 2017, APISAT 2017, Seoul, Korea},
  pages     = {15 Seiten},
  year      = {2017},
  language  = {en}
}
@inproceedings{FingerBraunBil2018,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {An Initial Sizing Methodology for Hybrid-Electric Light Aircraft},
  series = {AIAA AVIATION Forum 2018 Aviation Technology, Integration, and Operations Conference, Atlanta, Georgia, June 25 - 29, 2018},
  booktitle = {AIAA AVIATION Forum 2018 Aviation Technology, Integration, and Operations Conference, Atlanta, Georgia, June 25 - 29, 2018},
  doi       = {10.2514/6.2018-4229},
  year      = {2018},
  language  = {en}
}
@inproceedings{FingerBraunBil2019,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Impact of Engine Failure Constraints on the Initial Sizing of Hybrid-Electric GA Aircraft},
  series = {AIAA Scitech 2019 Forum},
  booktitle = {AIAA Scitech 2019 Forum},
  doi       = {10.2514/6.2019-1812},
  year      = {2019},
  language  = {en}
}
@article{FingerBraunBil2020,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft},
  series = {Journal of Aircraft},
  volume    = {57},
  journal   = {Journal of Aircraft},
  number    = {5},
  publisher = {AIAA},
  address   = {Reston, Va.},
  issn      = {1533-3868},
  doi       = {10.2514/1.C035897},
  year      = {2020},
  abstract  = {Until electric energy storage systems are ready to allow fully electric aircraft, the combination of combustion engine and electric motor as a hybrid-electric propulsion system seems to be a promising intermediate solution. Consequently, the design space for future aircraft is expanded considerably, as serial hybrid-electric, parallel hybrid-electric, fully electric, and conventional propulsion systems must all be considered. While the best propulsion system depends on a multitude of requirements and considerations, trends can be observed for certain types of aircraft and certain types of missions. This Paper provides insight into some factors that drive a new design toward either conventional or hybrid propulsion systems. General aviation aircraft, regional transport aircraft vertical takeoff and landing air taxis, and unmanned aerial vehicles are chosen as case studies. Typical missions for each class are considered, and the aircraft are analyzed regarding their takeoff mass and primary energy consumption. For these case studies, a high-level approach is chosen, using an initial sizing methodology. Only parallel-hybrid-electric powertrains are taken into account. Aeropropulsive interaction effects are neglected. Results indicate that hybrid-electric propulsion systems should be considered if the propulsion system is sized by short-duration power constraints. However, if the propulsion system is sized by a continuous power requirement, hybrid-electric systems offer hardly any benefit.},
  language  = {en}
}
@inproceedings{FingerBraunBil2020,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft},
  series = {AIAA SciTech Forum 2020, 06.01.2020 - 10.01.2020, Orlando},
  booktitle = {AIAA SciTech Forum 2020, 06.01.2020 - 10.01.2020, Orlando},
  doi       = {10.2514/6.2020-1502},
  pages     = {15 Seiten},
  year      = {2020},
  language  = {en}
}
@article{FingerBraunBil2020,
  author    = {Finger, Felix and Braun, Carsten and Bil, Cees},
  title     = {Impact of Battery Performance on the Initial Sizing of Hybrid-Electric General Aviation Aircraft},
  series = {Journal of Aerospace Engineering},
  volume    = {33},
  journal   = {Journal of Aerospace Engineering},
  number    = {3},
  publisher = {ASCE},
  address   = {Reston, Va.},
  issn      = {1943-5525},
  doi       = {10.1061/(ASCE)AS.1943-5525.0001113},
  year      = {2020},
  abstract  = {Studies suggest that hybrid-electric aircraft have the potential to generate fewer emissions and be inherently quieter when compared to conventional aircraft. By operating combustion engines together with an electric propulsion system, synergistic benefits can be obtained. However, the performance of hybrid-electric aircraft is still constrained by a battery's energy density and discharge rate. In this paper, the influence of battery performance on the gross mass for a four-seat general aviation aircraft with a hybrid-electric propulsion system is analyzed. For this design study, a high-level approach is chosen, using an innovative initial sizing methodology to determine the minimum required aircraft mass for a specific set of requirements and constraints. Only the peak-load shaving operational strategy is analyzed. Both parallel- and serial-hybrid propulsion configurations are considered for two different missions. The specific energy of the battery pack is varied from 200 to 1,000 W⋅h/kg, while the discharge time, and thus the normalized discharge rating (C-rating), is varied between 30 min (2C discharge rate) and 2 min (30C discharge rate). With the peak-load shaving operating strategy, it is desirable for hybrid-electric aircraft to use a light, low capacity battery system to boost performance. For this case, the battery's specific power rating proved to be of much higher importance than for full electric designs, which have high capacity batteries. Discharge ratings of 20C allow a significant take-off mass reduction aircraft. The design point moves to higher wing loadings and higher levels of hybridization if batteries with advanced technology are used.},
  language  = {en}
}
@article{FingerBilBraun2019,
  author    = {Finger, Felix and Bil, Cees and Braun, Carsten},
  title     = {Initial Sizing Methodology for Hybrid-Electric General Aviation Aircraft},
  series = {Journal of Aircraft},
  volume    = {57},
  journal   = {Journal of Aircraft},
  number    = {2},
  issn      = {1533-3868},
  doi       = {10.2514/1.C035428},
  pages     = {245 -- 255},
  year      = {2019},
  language  = {en}
}
@article{BoehnischBraunMuscarelloetal.2024,
  author    = {B{\"o}hnisch, Nils and Braun, Carsten and Muscarello, Vincenzo and Marzocca, Pier},
  title     = {About the wing and whirl flutter of a slender wing-propeller system},
  series = {Journal of Aircraft},
  journal   = {Journal of Aircraft},
  publisher = {American Institute of Aeronautics and Astronautics},
  issn      = {1533-3868},
  doi       = {10.2514/1.C037542},
  pages     = {1 -- 14},
  year      = {2024},
  abstract  = {Next-generation aircraft designs often incorporate multiple large propellers attached along the wingspan (distributed electric propulsion), leading to highly flexible dynamic systems that can exhibit aeroelastic instabilities. This paper introduces a validated methodology to investigate the aeroelastic instabilities of wing-propeller systems and to understand the dynamic mechanism leading to wing and whirl flutter and transition from one to the other. Factors such as nacelle positions along the wing span and chord and its propulsion system mounting stiffness are considered. Additionally, preliminary design guidelines are proposed for flutter-free wing-propeller systems applicable to novel aircraft designs. The study demonstrates how the critical speed of the wing-propeller systems is influenced by the mounting stiffness and propeller position. Weak mounting stiffnesses result in whirl flutter, while hard mounting stiffnesses lead to wing flutter. For the latter, the position of the propeller along the wing span may change the wing mode shapes and thus the flutter mechanism. Propeller positions closer to the wing tip enhance stability, but pusher configurations are more critical due to the mass distribution behind the elastic axis.},
  language  = {en}
}
@article{BoehnischBraunMuscarelloetal.2023,
  author    = {B{\"o}hnisch, Nils and Braun, Carsten and Muscarello, Vincenzo and Marzocca, Pier},
  title     = {A sensitivity study on aeroelastic instabilities of slender wings with a large propeller},
  series = {AIAA SCITECH 2023 Forum},
  journal   = {AIAA SCITECH 2023 Forum},
  publisher = {AIAA},
  doi       = {10.2514/6.2023-1893},
  pages     = {1 -- 14},
  year      = {2023},
  abstract  = {Next-generation aircraft designs often incorporate multiple large propellers attached along the wingspan. These highly flexible dynamic systems can exhibit uncommon aeroelastic instabilities, which should be carefully investigated to ensure safe operation. The interaction between the propeller and the wing is of particular importance. It is known that whirl flutter is stabilized by wing motion and wing aerodynamics. This paper investigates the effect of a propeller onto wing flutter as a function of span position and mounting stiffness between the propeller and wing. The analysis of a comparison between a tractor and pusher configuration has shown that the coupled system is more stable than the standalone wing for propeller positions near the wing tip for both configurations. The wing fluttermechanism is mostly affected by the mass of the propeller and the resulting change in eigenfrequencies of the wing. For very weak mounting stiffnesses, whirl flutter occurs, which was shown to be stabilized compared to a standalone propeller due to wing motion. On the other hand, the pusher configuration is, as to be expected, the more critical configuration due to the attached mass behind the elastic axis.},
  language  = {de}
}
@incollection{BrittenBraunHesseetal.2003,
  author    = {Britten, G. and Braun, Carsten and Hesse, M. and Ballmann, Josef},
  title     = {Computational aeroelasticity with reduced structural models},
  series = {Flow modulation and fluid-structure interaction at airplane wings : research results of the Collaborative Research Center SFB 401 at RWTH Aachen, University of Technology, Aachen, Germany / Josef Ballmann (Ed.) Notes on numerical fluid mechanics and multidisciplinary design. Vol. 84},
  booktitle = {Flow modulation and fluid-structure interaction at airplane wings : research results of the Collaborative Research Center SFB 401 at RWTH Aachen, University of Technology, Aachen, Germany / Josef Ballmann (Ed.) Notes on numerical fluid mechanics and multidisciplinary design. Vol. 84},
  publisher = {Springer},
  address   = {Berlin},
  isbn      = {3-540-40209-8},
  pages     = {275 -- 299},
  year      = {2003},
  language  = {en}
}
@incollection{BraunBouckeHankeetal.2003,
  author    = {Braun, Carsten and Boucke, Alexander and Hanke, M. and Karavas, Alexandros and Ballmann, Josef},
  title     = {Prediction of the model deformation of a high speed transport aircraft type wing by direct aeroelastic simulation},
  series = {High performance computing in science and engineering '03. Transactions of the High Performance Computing Center Stuttgart (HLRS) 2003 / Eds.: Egon Krause ...},
  booktitle = {High performance computing in science and engineering '03. Transactions of the High Performance Computing Center Stuttgart (HLRS) 2003 / Eds.: Egon Krause ...},
  publisher = {Springer},
  address   = {Berlin},
  isbn      = {978-3-540-40850-5},
  pages     = {331 -- 342},
  year      = {2003},
  language  = {de}
}
@inproceedings{BraunBouckeBallmann2005,
  author    = {Braun, Carsten and Boucke, Alexander and Ballmann, Josef},
  title     = {Numerical prediction of the wing deformation of a high speed transport aircraft type wind tunnel model by direct aeroelastic simulation},
  series = {Conference proceedings : CEAS/AIAA/DGLR International Forum on Aeroelasticity and Structural Dynamics IFASD 2005 : M{\"u}nchen, June 28 - July 1, 2005. DGLR-Bericht. 2005,04},
  booktitle = {Conference proceedings : CEAS/AIAA/DGLR International Forum on Aeroelasticity and Structural Dynamics IFASD 2005 : M{\"u}nchen, June 28 - July 1, 2005. DGLR-Bericht. 2005,04},
  publisher = {DGLR},
  address   = {Bonn},
  isbn      = {3-932182-43-X},
  pages     = {1 CD-ROM},
  year      = {2005},
  language  = {en}
}
@incollection{BraunBouckeBallmann2005,
  author    = {Braun, Carsten and Boucke, Alexander and Ballmann, Josef},
  title     = {Numerical study of the influence of dynamic pressure and deflected ailerons on the deformation of a high speed wing model},
  series = {High performance computing in science and engineering '04. Transactions of the High Performance Computing Center Stuttgart (HLRS) 2004 / Eds.: Egon Krause ...},
  booktitle = {High performance computing in science and engineering '04. Transactions of the High Performance Computing Center Stuttgart (HLRS) 2004 / Eds.: Egon Krause ...},
  publisher = {Springer},
  address   = {Berlin},
  isbn      = {3-540-22943-4},
  pages     = {225 -- 236},
  year      = {2005},
  language  = {en}
}
@inproceedings{Braun2008,
  author    = {Braun, Carsten},
  title     = {Ein modulares Verfahren f{\"u}r die numerische aeroelastische Analyse von Luftfahrzeugen},
  series = {Motto: Wissen und Visionen f{\"u}r ein nachhaltiges Wachstum : Deutscher Luft- und Raumfahrtkongress 2008, Darmstadt, 23. bis 25. September 2008 / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). DGLR-Jahrbuch. 2008},
  booktitle = {Motto: Wissen und Visionen f{\"u}r ein nachhaltiges Wachstum : Deutscher Luft- und Raumfahrtkongress 2008, Darmstadt, 23. bis 25. September 2008 / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). DGLR-Jahrbuch. 2008},
  publisher = {DGLR},
  address   = {Bonn},
  pages     = {787 -- 796},
  year      = {2008},
  language  = {de}
}
@book{Braun2007,
  author    = {Braun, Carsten},
  title     = {Ein modulares Verfahren f{\"u}r die numerische aeroelastische Analyse von Luftfahrzeugen},
  pages     = {VI, 199 S.},
  year      = {2007},
  abstract  = {Aachen, Techn. Hochschule, Diss., 2007},
  language  = {de}
}
@article{BergmannMoehrenBraunetal.2023,
  author    = {Bergmann, Ole and M{\"o}hren, Felix and Braun, Carsten and Janser, Frank},
  title     = {On the influence of elasticity on swept propeller noise},
  series = {AIAA SCITECH 2023 Forum},
  journal   = {AIAA SCITECH 2023 Forum},
  publisher = {AIAA},
  doi       = {10.2514/6.2023-0210},
  year      = {2023},
  abstract  = {High aerodynamic efficiency requires propellers with high aspect ratios, while propeller sweep potentially reduces noise. Propeller sweep and high aspect ratios increase elasticity and coupling of structural mechanics and aerodynamics, affecting the propeller performance and noise. Therefore, this paper analyzes the influence of elasticity on forward-swept, backward-swept, and unswept propellers in hover conditions. A reduced-order blade element momentum approach is coupled with a one-dimensional Timoshenko beam theory and Farassat's formulation 1A. The results of the aeroelastic simulation are used as input for the aeroacoustic calculation. The analysis shows that elasticity influences noise radiation because thickness and loading noise respond differently to deformations. In the case of the backward-swept propeller, the location of the maximum sound pressure level shifts forward by 0.5 °, while in the case of the forward-swept propeller, it shifts backward by 0.5 °. Therefore, aeroacoustic optimization requires the consideration of propeller deformation.},
  language  = {en}
}
@inproceedings{BergmannGoettenBraunetal.2022,
  author    = {Bergmann, Ole and G{\"o}tten, Falk and Braun, Carsten and Janser, Frank},
  title     = {Comparison and evaluation of blade element methods against RANS simulations and test data},
  series = {CEAS Aeronautical Journal},
  volume    = {13},
  booktitle = {CEAS Aeronautical Journal},
  publisher = {Springer},
  address   = {Wien},
  issn      = {1869-5590 (Online)},
  doi       = {10.1007/s13272-022-00579-1},
  pages     = {535 -- 557},
  year      = {2022},
  abstract  = {This paper compares several blade element theory (BET) method-based propeller simulation tools, including an evaluation against static propeller ground tests and high-fidelity Reynolds-Average Navier Stokes (RANS) simulations. Two proprietary propeller geometries for paraglider applications are analysed in static and flight conditions. The RANS simulations are validated with the static test data and used as a reference for comparing the BET in flight conditions. The comparison includes the analysis of varying 2D aerodynamic airfoil parameters and different induced velocity calculation methods. The evaluation of the BET propeller simulation tools shows the strength of the BET tools compared to RANS simulations. The RANS simulations underpredict static experimental data within 10\% relative error, while appropriate BET tools overpredict the RANS results by 15-20\% relative error. A variation in 2D aerodynamic data depicts the need for highly accurate 2D data for accurate BET results. The nonlinear BET coupled with XFOIL for the 2D aerodynamic data matches best with RANS in static operation and flight conditions. The novel BET tool PropCODE combines both approaches and offers further correction models for highly accurate static and flight condition results.},
  language  = {en}
}
@inproceedings{BallmannDafnisBraunetal.2006,
  author    = {Ballmann, Josef and Dafnis, Athanasios and Braun, Carsten and Korsch, Helge and Reimerdes, Hans-G{\"u}nther and Braun, Carsten and Ballmann, Josef},
  title     = {The HIRENASD project: High Reynolds number aerostructural dynamics experiments in the European Transonic Wind Tunnel (ETW)},
  series = {ICAS 2006 proceedings : 25th Congress of the International Council of the Aeronautical Sciences ; Hamburg, Germany, 3 - 8 September, 2006 : 25th International Congress of Aeronautical Sciences},
  booktitle = {ICAS 2006 proceedings : 25th Congress of the International Council of the Aeronautical Sciences ; Hamburg, Germany, 3 - 8 September, 2006 : 25th International Congress of Aeronautical Sciences},
  publisher = {Optimage},
  address   = {Edinburgh},
  organization    = {International Council of the Aeronautical Sciences (ICAS)},
  isbn      = {0-9533991-7-6},
  pages     = {Paper No. 2006-5.11.2},
  year      = {2006},
  language  = {en}
}
@incollection{BallmannBouckeBraun2003,
  author    = {Ballmann, Josef and Boucke, Alexander and Braun, Carsten},
  title     = {Aeroelastic sensitivity in the transonic regime},
  series = {Symposium Transsonicum IV : proceedings of the IUTAM symposium held in G{\"o}ttingen, Germany, 2 - 6 September 2002 / ed. by Helmut Sobieczky. Fluid mechanics and its applications. Vol. 73},
  booktitle = {Symposium Transsonicum IV : proceedings of the IUTAM symposium held in G{\"o}ttingen, Germany, 2 - 6 September 2002 / ed. by Helmut Sobieczky. Fluid mechanics and its applications. Vol. 73},
  publisher = {Kluwer Academic},
  address   = {Dordrecht},
  isbn      = {978-94-010-3998-7},
  pages     = {225 -- 236},
  year      = {2003},
  language  = {en}
}