@book{AppelBraehlerDahlhausetal.2010,
  author    = {Appel, Wolfgang and Br{\"a}hler, Hermann and Dahlhaus, Ulrich and Esch, Thomas and Kopp, Stephan and Rhein, Bernd},
  title     = {Nutzfahrzeugtechnik : Grundlagen, Systeme, Komponenten. 6., {\"u}berarb. Aufl.},
  publisher = {Vieweg + Teubner},
  address   = {Wiesbaden},
  isbn      = {978-3-8348-9757-2},
  pages     = {XXVIII, 509 S. : Ill., graph. Darst.},
  year      = {2010},
  language  = {de}
}
@book{AppelBraehlerBreueretal.2013,
  author    = {Appel, Wolfgang and Br{\"a}hler, Hermann and Breuer, Stefan and Dahlhaus, Ulrich and Esch, Thomas and Hoepke, Erich and Kopp, Stephan and Rhein, Bernd},
  title     = {Nutzfahrzeugtechnik : Grundlagen, Systeme, Komponenten. 7., {\"u}berarb. u. erw. Aufl.},
  publisher = {Vieweg + Teubner},
  address   = {Wiesbaden},
  isbn      = {978-3-8348-2224-6},
  pages     = {XXXII, 620 S. : Ill., graph. Darst.},
  year      = {2013},
  language  = {de}
}
@article{BlomeWilson1996,
  author    = {Blome, Hans-Joachim and Wilson, Thomas L.},
  title     = {Observational cosmology from the moon. Wilson, Thomas, L.; Blome, Hans-Joachim},
  series = {Engineering, construction, and operations in space V : proceedings of the Fifth International Conference on Space '96, Albuquerque, New Mexico, June 1-6, 1996 / sponsored by Aerospace Division of the American Society of Civil Engineers ... [et al.]; edite},
  journal   = {Engineering, construction, and operations in space V : proceedings of the Fifth International Conference on Space '96, Albuquerque, New Mexico, June 1-6, 1996 / sponsored by Aerospace Division of the American Society of Civil Engineers ... [et al.]; edite},
  publisher = {The Society},
  address   = {New York},
  isbn      = {0-7844-0177-2},
  pages     = {864 -- 870},
  year      = {1996},
  language  = {en}
}
@article{Dahmann1995,
  author    = {Dahmann, Peter},
  title     = {Offen f{\"u}r neue Modelle. GL-Hydraulik setzt neues Simulationssystem ein},
  series = {Fluid Heft Sonderpublikation Fluid-Technik. 29 (1995)},
  journal   = {Fluid Heft Sonderpublikation Fluid-Technik. 29 (1995)},
  isbn      = {0015-461X},
  pages     = {8 -- 10},
  year      = {1995},
  language  = {de}
}
@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{GoettenHavermannBraunetal.2018,
  author    = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bil, Cees},
  title     = {On the Applicability of Empirical Drag Estimation Methods for Unmanned Air Vehicle Design Read More: https://arc.aiaa.org/doi/10.2514/6.2018-3192},
  series = {2018 Aviation Technology, Integration, and Operations Conference, AIAA AVIATION Forum},
  booktitle = {2018 Aviation Technology, Integration, and Operations Conference, AIAA AVIATION Forum},
  issn      = {1533-385X},
  doi       = {10.2514/6.2018-3192},
  pages     = {Article 3192},
  year      = {2018},
  language  = {en}
}
@inproceedings{MoehrenBergmannJanseretal.2023,
  author    = {M{\"o}hren, Felix and Bergmann, Ole and Janser, Frank and Braun, Carsten},
  title     = {On the determination of harmonic propeller loads},
  series = {AIAA SCITECH 2023 Forum},
  booktitle = {AIAA SCITECH 2023 Forum},
  publisher = {AIAA},
  doi       = {10.2514/6.2023-2404},
  pages     = {12 Seiten},
  year      = {2023},
  abstract  = {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.},
  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}
}
@article{MoehrenBergmannJanseretal.2023,
  author    = {M{\"o}hren, Felix and Bergmann, Ole and Janser, Frank and Braun, Carsten},
  title     = {On the influence of elasticity on propeller performance: a parametric study},
  series = {CEAS Aeronautical Journal},
  volume    = {14},
  journal   = {CEAS Aeronautical Journal},
  publisher = {Springer Nature},
  address   = {Berlin},
  issn      = {1869-5590 (Online)},
  doi       = {10.1007/s13272-023-00649-y},
  pages     = {311 -- 323},
  year      = {2023},
  abstract  = {The aerodynamic performance of propellers strongly depends on their geometry and, consequently, on aeroelastic deformations. Knowledge of the extent of the impact is crucial for overall aircraft performance. An integrated simulation environment for steady aeroelastic propeller simulations is presented. The simulation environment is applied to determine the impact of elastic deformations on the aerodynamic propeller performance. The aerodynamic module includes a blade element momentum approach to calculate aerodynamic loads. The structural module is based on finite beam elements, according to Timoshenko theory, including moderate deflections. Several fixed-pitch propellers with thin-walled cross sections made of both isotropic and non-isotropic materials are investigated. The essential parameters are varied: diameter, disc loading, sweep, material, rotational, and flight velocity. The relative change of thrust between rigid and elastic blades quantifies the impact of propeller elasticity. Swept propellers of large diameters or low disc loadings can decrease the thrust significantly. High flight velocities and low material stiffness amplify this tendency. Performance calculations without consideration of propeller elasticity can lead to decreased efficiency. To avoid cost- and time-intense redesigns, propeller elasticity should be considered for swept planforms and low disc loadings.},
  language  = {en}
}
@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}
}