@article{FingerGoetten2019,
  author    = {Finger, Felix and G{\"o}tten, Falk},
  title     = {Neue Ans{\"a}tze f{\"u}r die Entwicklung von unbemannten Flugger{\"a}ten},
  series = {Ingenieurspiegel},
  volume    = {2019},
  journal   = {Ingenieurspiegel},
  number    = {1},
  isbn      = {1868-5919},
  pages     = {67 -- 68},
  year      = {2019},
  abstract  = {Wie sieht das unbemannte Flugzeug von {\"U}bermorgen aus? Dieser Frage stellen sich Forscher an der Fachhochschule Aachen. Die weltweit rasant fortschreitende Entwicklung des Marktes f{\"u}r unbemannte Flugger{\"a}te (UAVs - „Unmanned Aerial Vehicles") bietet großes Potenzial f{\"u}r Wachstum und Wertsch{\"o}pfung. Unbemannte fliegende Systeme k{\"o}nnen - f{\"u}r bestimmte Anwendungsgebiete - wesentlich g{\"u}nstiger, kleiner und effizienter ausgelegt werden als bemannte L{\"o}sungen. Dabei sind sich viele Unternehmen {\"u}ber das m{\"o}gliche Potential dieser Technologie noch gar nicht bewusst.},
  language  = {de}
}
@article{DachwaldWurm2011,
  author    = {Dachwald, Bernd and Wurm, Patrick},
  title     = {Mission analysis and performance comparison for an Advanced Solar Photon Thruster},
  series = {Advances in Space Research},
  volume    = {48},
  journal   = {Advances in Space Research},
  number    = {11},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0273-1177},
  pages     = {1858 -- 1868},
  year      = {2011},
  language  = {en}
}
@article{ScholzLeyDachwaldetal.2010,
  author    = {Scholz, A. and Ley, Wilfried and Dachwald, Bernd and Miau, J. J. and Juang, J. C.},
  title     = {Flight results of the COMPASS-1 picosatellite mission},
  series = {Acta Astronautica. 67 (2010), H. 9-10},
  journal   = {Acta Astronautica. 67 (2010), H. 9-10},
  isbn      = {0094-5765},
  pages     = {1289 -- 1298},
  year      = {2010},
  language  = {en}
}
@article{Dahmann1990,
  author    = {Dahmann, Peter},
  title     = {Leistungsf{\"a}higkeit von Hydraulikfiltern bei unterschiedlichen Betriebsbedingungen},
  series = {{\"O}lhydraulik und Pneumatik. 34 (1990), H. 10},
  journal   = {{\"O}lhydraulik und Pneumatik. 34 (1990), H. 10},
  isbn      = {0341-2660},
  pages     = {682 -- 688},
  year      = {1990},
  language  = {de}
}
@article{MaiwaldDachwald2010,
  author    = {Maiwald, Volker and Dachwald, Bernd},
  title     = {Mission Design for a Multiple-Rendezvous Mission to Jupiter's Trojans},
  pages     = {3},
  year      = {2010},
  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{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{SchildtBraunMarzocca2019,
  author    = {Schildt, Ph. and Braun, Carsten and Marzocca, P.},
  title     = {Metric evaluating potentials of condition-monitoring approaches for hybrid electric aircraft propulsion systems},
  series = {CEAS Aeronautical Journal},
  journal   = {CEAS Aeronautical Journal},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1869-5590},
  doi       = {10.1007/s13272-019-00411-3},
  pages     = {1 -- 14},
  year      = {2019},
  language  = {en}
}
@article{FunkeBeckmannKeinzetal.2016,
  author    = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester},
  title     = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion},
  series = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016},
  journal   = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016},
  publisher = {ASME},
  address   = {New York, NY},
  isbn      = {978-0-7918-4975-0},
  doi       = {10.1115/GT2016-56430},
  pages     = {12},
  year      = {2016},
  abstract  = {The Dry-Low-NOₓ (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOₓ emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOₓ emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H₂-CO) numerical analyses based on a skeletal H₂/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.},
  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}
}