Periodic Reporting for period 2 - CHYLA (Credible HYbrid eLectric Aircraft)
Berichtszeitraum: 2021-12-01 bis 2023-05-31
Design of the next generation of transport aircraft includes a combination of novel technologies with novel aircraft configurations. However, when to apply which technology and to what category of aircraft is not well understood. The aim is to identify opportunities and limitations of scaling of main technology applications, i.e. “switching points” across different classes of vehicles. These different fixed wing vehicle classes of aircraft are: 1) general aviation, 2) commuter aircraft, 3) regional aircraft, 4) short-medium range aircraft and 5) large passenger aircraft. The switch-over points between different technologies and system architectures are not yet well known and may also depend on aspects such as certification, operating environment or speed.
The identification of such a landscape of opportunities and limitations of key technology applications should benefit the development of (more) sustainable and environmentally friendly aircraft, to reduce the climate impact of aviation in the future and sustain general travel needs and desires with cleaner means of transportation. Such a landscape may steer future research efforts in the most relevant directions in order to mature technologies and their applications. With all partners being educational institutes, CHYLA’s developments and research directly contribute to the education of new generations of aerospace engineers.
A notional landscape of the application areas across the different vehicle classes is presented in the attached image. This image also summarizes the key results for the project.
Overall it may be concluded that:
1) For general aviation, up to ~600kg payload can be transported fully electrically over ranges up to 400km, beyond this up to 600km a serial hybrid electric powertrain is beneficial with respect to conventional kerosene.
2) For commuter aircraft, with 19 passengers, a serial hybrid electric powertrain is limited to 180km range when it has to remain within CS23 weight limit, or 10 passengers at ~300km. Beyond this range, CS25 regulations are applicable.
3) For regional propeller aircraft a clear trend emerges with between 10 and maximum 20% supplied battery power (to remain within 36m span limit): serial hybrid electric is outperformed by parallel boosted turboprop, which are both outperformed by the most complex hybrid electric powertrain. However, during off-design operation this may be different. Off-design operation is particularly interesting because fuel savings with respect kerosene aircraft (up to 50% fuel savings depending on the particular design for 70 passengers transported over 500km).
4) For larger jet airliners, liquid hydrogen combustion is the only potentially feasible solution though it comes at the cost of more weight and longer fuselage. The latter may be challenging in terms of airport limits and may require a double deck design.
5) High-power charging facilities: >400kW are required; Charging time is seen to have a relatively large impact on fleet electrification
The identification of such a landscape of opportunities and limitations of key technology applications should benefit the development of (more) sustainable and environmentally friendly aircraft, to reduce the climate impact of aviation in the future and sustain general travel needs and desires with cleaner means of transportation. Such a landscape may steer future research efforts in the most relevant directions in order to mature technologies and their applications. With all partners being educational institutes, CHYLA’s developments and research directly contribute to the education of new generations of aerospace engineers.
A notional landscape of the application areas across the different vehicle classes is presented in the attached image. This image also summarizes the key results for the project.
Overall it may be concluded that:
1) For general aviation, up to ~600kg payload can be transported fully electrically over ranges up to 400km, beyond this up to 600km a serial hybrid electric powertrain is beneficial with respect to conventional kerosene.
2) For commuter aircraft, with 19 passengers, a serial hybrid electric powertrain is limited to 180km range when it has to remain within CS23 weight limit, or 10 passengers at ~300km. Beyond this range, CS25 regulations are applicable.
3) For regional propeller aircraft a clear trend emerges with between 10 and maximum 20% supplied battery power (to remain within 36m span limit): serial hybrid electric is outperformed by parallel boosted turboprop, which are both outperformed by the most complex hybrid electric powertrain. However, during off-design operation this may be different. Off-design operation is particularly interesting because fuel savings with respect kerosene aircraft (up to 50% fuel savings depending on the particular design for 70 passengers transported over 500km).
4) For larger jet airliners, liquid hydrogen combustion is the only potentially feasible solution though it comes at the cost of more weight and longer fuselage. The latter may be challenging in terms of airport limits and may require a double deck design.
5) High-power charging facilities: >400kW are required; Charging time is seen to have a relatively large impact on fleet electrification
Reporting period 1 primarily consisted of the project startup involving the definition of top level requirements and identifying suitable reference aircraft. Additionally, a set of key performance indicators have been defined. The reference aircraft and baseline designs have been evaluated with the aircraft design software to define a basis for comparison of the to be developed radical aircraft designs. A matrix, containing the various propulsion layouts, powertrain architectures and energy carriers has been made, which also contains the most-likely applications to different aircraft classes. This defines the starting point for the radical designs and optimization, scalability assessment and sensitivity studies to be performed in the second reporting period. Moreover, an energy network model (to evaluate different propulsion layouts, powertrain architectures and energy carriers in detail) has been made.
Reporting period 2 focused primarily on generating the results for the different design, optimization and sensitivity studies. Additionally, several interesting developments have been made that form key exploitable results for the project. A summary is presented below. Full list (10+ articles) and links to dissemination can be found on:
https://www.tudelft.nl/lr/chyla-project/publications
- Credibility-based MDO method: PhD study + Education; (https://arc.aiaa.org/doi/10.2514/6.2023-1847 https://www.researchgate.net/publication/367319125_Credibility-Based_Multidisciplinary_Design_Optimisation_of_Electric_Aircraft , http://www.icas.org/ICAS_ARCHIVE/ICAS2022/data/papers/ICAS2022_0850_paper.pdf , submitted to AIAA journal of aircraft)
- EGO constraint optimization: PhD study + Education; (submitted to AIAA journal of aircraft)
- (Hybrid) Electric Energy Network: PhD study + future projects; (http://www.icas.org/ICAS_ARCHIVE/ICAS2022/data/papers/ICAS2022_0850_paper.pdf , https://www.researchgate.net/publication/361451255_An_Integrated_Framework_for_Energy_Network_Modeling_in_Hybrid-Electric_Aircraft_Conceptual_Design)
- Off-design performance analysis for hybrid electric aircraft: CA projects (HERA) + other research projects + education (MSc research); (https://arc.aiaa.org/doi/10.2514/6.2023-2098 http://resolver.tudelft.nl/uuid:cc9b9cb3-292a-4056-9575-8f70396eb2bf , submitted to CEAS 2023 conference , to be submitted to AIAA journal of aircraft)
- Regional Operative Scenario: CA projects (HERA) + other research projects + PhD research + education (MSc research); (submitted to AIAA Aviation 2023 and CEAS 2023)
- Coupled aircraft design & strategic airline planning & climate optimization: CA projects (HERA) + other research projects + PhD research + education (MSc research); (submitted to AIAA Aviation 2023)
- Development of sizing method and assessment of hydrogen tank integration: PhD research + education + other research project; (https://doi.org/10.1007/s13272-022-00601-6)
Reporting period 2 focused primarily on generating the results for the different design, optimization and sensitivity studies. Additionally, several interesting developments have been made that form key exploitable results for the project. A summary is presented below. Full list (10+ articles) and links to dissemination can be found on:
https://www.tudelft.nl/lr/chyla-project/publications
- Credibility-based MDO method: PhD study + Education; (https://arc.aiaa.org/doi/10.2514/6.2023-1847 https://www.researchgate.net/publication/367319125_Credibility-Based_Multidisciplinary_Design_Optimisation_of_Electric_Aircraft , http://www.icas.org/ICAS_ARCHIVE/ICAS2022/data/papers/ICAS2022_0850_paper.pdf , submitted to AIAA journal of aircraft)
- EGO constraint optimization: PhD study + Education; (submitted to AIAA journal of aircraft)
- (Hybrid) Electric Energy Network: PhD study + future projects; (http://www.icas.org/ICAS_ARCHIVE/ICAS2022/data/papers/ICAS2022_0850_paper.pdf , https://www.researchgate.net/publication/361451255_An_Integrated_Framework_for_Energy_Network_Modeling_in_Hybrid-Electric_Aircraft_Conceptual_Design)
- Off-design performance analysis for hybrid electric aircraft: CA projects (HERA) + other research projects + education (MSc research); (https://arc.aiaa.org/doi/10.2514/6.2023-2098 http://resolver.tudelft.nl/uuid:cc9b9cb3-292a-4056-9575-8f70396eb2bf , submitted to CEAS 2023 conference , to be submitted to AIAA journal of aircraft)
- Regional Operative Scenario: CA projects (HERA) + other research projects + PhD research + education (MSc research); (submitted to AIAA Aviation 2023 and CEAS 2023)
- Coupled aircraft design & strategic airline planning & climate optimization: CA projects (HERA) + other research projects + PhD research + education (MSc research); (submitted to AIAA Aviation 2023)
- Development of sizing method and assessment of hydrogen tank integration: PhD research + education + other research project; (https://doi.org/10.1007/s13272-022-00601-6)
The project results and landscape of opportunities and limitations of key technology applications should benefit the development of (more) sustainable and environmentally friendly aircrafth. On a socio-economic scale, the project results may help to reduce the climate impact of aviation in the future and highlights the requirements for future developments. Additionally, the results clearly identify the most interesting areas in terms of CO2 reduction. From an operations side, it is clear which technology requirements may strengthen the commercially and environmentally interesting adoption of hybrid electric technologies. Additionally, since all partners are educational institutes, the developments and research will directly contribute to the education of new generations of aerospace engineers.
In terms of progress beyond the state of the art, the following contributions have been made:
- Credibility-based MDO method
- EGO algorithm for constraint optimization
- (Hybrid) Electric Energy Network
- Off-design performance analysis for hybrid electric aircraft
- Development of sizing method and assessment of hydrogen tank integration
- Coupled aircraft design & strategic airline planning & climate optimization
- Regional Operative Scenario for hybrid and electric aircraft
In terms of progress beyond the state of the art, the following contributions have been made:
- Credibility-based MDO method
- EGO algorithm for constraint optimization
- (Hybrid) Electric Energy Network
- Off-design performance analysis for hybrid electric aircraft
- Development of sizing method and assessment of hydrogen tank integration
- Coupled aircraft design & strategic airline planning & climate optimization
- Regional Operative Scenario for hybrid and electric aircraft