06 Fakultät Luft- und Raumfahrttechnik und Geodäsie

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7

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Institute: search.filters.UBSInstitut.Institut für Flugmechanik und FlugregelungInstitute: search.filters.UBSInstitut.Institut für FlugzeugbauAuthor: search.filters.author.Strohmayer, AndreasAuthor: search.filters.author.Denzel, JanSubject: search.filters.subject.620

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    In-flight lift and drag estimation of an unmanned propeller-driven aircraft
    (2021) Bergmann, Dominique Paul; Denzel, Jan; Pfeifle, Ole; Notter, Stefan; Fichter, Walter; Strohmayer, Andreas
    The high-power density and good scaling properties of electric motors enable new propulsion arrangements and aircraft configurations. This results in distributed propulsion systems allowing to make use of aerodynamic interaction effects between individual propellers and the wing of the aircraft, improving flight performance and thus reducing in-flight emissions. In order to systematically analyze these effects, an unmanned research platform was designed and built at the University of Stuttgart. As the aircraft is being used as a testbed for various flight performance studies in the field of distributed electric propulsion, a methodology for precise identification of its performance characteristics is required. One of the main challenges is the determination of the total drag of the aircraft to be able to identify an exact drag and lift polar in flight. For this purpose, an on-board measurement system was developed which allows for precise determination of the thrust of the aircraft which equals the total aerodynamic drag in steady, horizontal flight. The system has been tested and validated in flight using the unmanned free-flight test platform. The article provides an overview of the measuring system installed, discusses its functionality and shows results of the flight tests carried out.
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    Cruise flight simulation of distributed propulsion and wingtip-mounted propeller aircraft and their validation with in-flight measurement data
    (2025) Schollenberger, Michael; Firnhaber Beckers, Mário; Lutz, Thorsten; Krämer, Ewald; Bergmann, Dominique; Denzel, Jan; Strohmayer, Andreas; Pfeifle, Ole; Fichter, Walter
    The utilization of aerodynamic interactions between propellers and wings through distributed propulsion (DP) and wing tip mounted propellers (WTP) offers a range of advantages for electrically powered aircraft, from improved high-lift behavior to increased aerodynamic efficiency in cruise flight. In the LuFo project VELAN, a DP configuration of the unmanned scaled flight demonstrator e-Genius-Mod is currently being investigated, following the evaluation of a pure WTP variant in the LuFo project ELFLEAN. For both concepts, a numerical analysis with the Reynolds-Averaged Navier-Stokes (RANS)-based flow solver TAU is discussed in this paper and the influence of various parameters is addressed, such as the flight speed and the thrust ratio of the propellers. To ensure a reliable prediction of the cruise flight condition and the aerodynamic effects in the numerical simulations, the CFD methods are validated with experimental data from wind tunnels and in-flight tests. The cruise flight condition in the simulation is achieved by an algorithm for adjusting the propeller thrust to the aircraft drag, resulting in qualitatively and quantitatively accurate results. Both concepts improve the aerodynamic efficiency in cruise flight, which improves as the ratio of WTP thrust to the total thrust increases. In relation to each isolated wing, over 6%increased aerodynamic efficiency can be achieved with the WTP configuration and almost 5%with the DP concept. In absolute values, the optimal WTP aircraft achieves an aerodynamic efficiency of 21.5, which is 3%higher than with the most efficient DP configuration.