The objective of the present work is the development and application of a conceptual design method for electric and hybrid propulsion systems in small aircraft. The method is applied to design propulsion systems for a motorized glider with a maximum take-off mass of 1000 kg. Four propulsion systems are investigated: the conventional internal combustion engine, the fully electric, the parallel, and series hybrid propulsion system. Key physical relationships, trade-offs, and design decisions are discussed and a comparison between the propulsion systems is made. On this basis, the suitability of the propulsion systems is evaluated with respect to different thrust requirements. The design method can be used to evaluate the influence of design parameters and operating strategies of hybrid propulsion systems on key targets such as system mass and cruise efficiency. Detailed component models are used to capture all interrelationships and operational limitations essential to the conceptual design. The design method is applied to study the suitability of the propulsion systems for different thrust requirements. The four propulsion systems considered are each designed for two different sets of thrust requirements. All propulsion systems are capable of the same flight mission, which allows for a meaningful comparison between the propulsion systems. Due to the high gravimetric power density of electric components and high efficiencies over a wide operating range, the electric propulsion system is suitable for high peak power combined with low cruise power. However, cruise range is limited due to the high battery mass. At a range of 300 km, the electric propulsion system is 2.6 times heavier than the conventional propulsion system. Within the study, the electric power of the hybrid propulsion systems is used for a boost during take-off. With this control strategy and the current technology level, the parallel hybrid propulsion system is able to achieve a lower total mass than the conventional propulsion system if the propeller power ratio between take-off and cruise is bigger than three. The downsizing of the internal combustion engine results in cruise efficiency advantages if the ratio is bigger than two. In this study, with a power ratio of 4.4, the parallel hybrid propulsion system can achieve a cruise efficiency that is 12 % higher and a total mass that is 8 % lower than the conventional propulsion system. The series hybrid propulsion system has significant disadvantages compared to conventional and parallel hybrid propulsion systems and should only be used if the aircraft design requires it. This study demonstrates that system considerations are necessary for concept evaluations and designs of electric and hybrid propulsion systems in small aircraft. The developed method is able to model all interrelationships between propulsion components relevant to the conceptual design and to determine system optima.


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    Title :

    Entwurfsmethode für elektrische und hybride Kleinflugzeugantriebe


    Additional title:

    Conceptual design method for electric and hybrid electric propulsion systems in small aircraft


    Contributors:

    Publication date :

    2022-01-01


    Size :

    1 Online-Ressource : Illustrationen, Diagramme pages


    Remarks:

    Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2022). doi:10.18154/RWTH-2022-09519 = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022



    Type of media :

    Miscellaneous


    Type of material :

    Electronic Resource


    Language :

    German




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