Preliminary Sizing of Electric-Propulsion Powertrains for Concept Aircraft Designs

The drive towards a greener and more sustainable future is encouraging the aviation industry to move towards increasing electrification of its fleet. The development of electric propulsion technologies also requires new approaches to assess their viability in novel configurations. A methodology is proposed which consists of four sub-procedures; powertrain modelling, performance analysis, aerodynamic modelling, and sizing. This approach initially considers powertrain modelling using AIAA symbol representations, and a review of the available literature establishes state-of-the-art component values of efficiency, specific power, specific energy, and specific fuel consumption. The sizing procedure includes a mission and aerodynamic analysis to determine the energy and power requirements, and it relies on a mass regression model based on full-electric, hybrid, VTOL and fixed-wing aircraft found in the literature. The methodology has been applied to five case studies which are representative of a wide range of missions and configurations. Their predicted masses from the sizing procedure have been validated against their actual masses. The predicted total mass shows generally good agreement with the actual values, and in addition, accurate values for active mass have been predicted. A sensitivity analysis of the sizing procedure suggests that future work may include a more accurate analysis of aerodynamics and mission if the methodology were to be applied for selecting aircraft concepts

Micro-Hydropower in Nepal:Analysing the Project Process to Understand Drivers that Strengthen and Weaken Sustainability

Evaluating the sustainable operation of community-owned and community-operated renewable energy projects is complex. The development of a project often depends on the actions of diverse stakeholders, including the government, industry and communities. Throughout the project cycle, these interrelated actions impact the sustainability of the project. In this paper, the typical project cycle of a micro-hydropower plant in Nepal is used to demonstrate that key events throughout the project cycle affect a plant’s ability to operate sustainably. Through a critical analysis of the available literature, policy and project documentation and interviews with manufacturers, drivers that affect the sustainability of plants are found. Examples include weak specification of civil components during tendering, quality control issues during manufacture, poor quality of construction and trained operators leaving their position. Opportunities to minimise both the occurrence and the severity of threats to sustainability are identified. For the micro-hydropower industry in Nepal, recommendations are made for specific actions by the relevant stakeholders at appropriate moments in the project cycle. More broadly, the findings demonstrate that the complex nature of developing community energy projects requires a holistic consideration of the complete project process

Modelling Green VTOL Concept Designs for Reliability and Efficiency

All-electric and hybrid-electric aircraft are a future transport goal and a possible ‘green’ solution to increasing climate-related pressures for aviation. Ensuring the safety of passengers is of high importance, informed through appropriate reliability predictions to satisfy emerging flight certification requirements. This paper introduces another important consideration related to redundancy offered by multiplex electric motors, a maturing technology which could help electric aircraft manufacturers meet the high reliability targets being set. A concept design methodology is overviewed involving a symbolic representation of aircraft and block modelling of two important figures of merit, reliability, and efficiency, supported by data. This leads to a comparative study of green aircraft configurations indicating which have the most potential now, and in the future. Two main case studies are then presented: an electric tail rotor retrofitted to an existing turbine powered helicopter (hybrid) and an eVTOL aircraft (all-electric), demonstrating the impact of multiplex level and number of propulsion channels on meeting target reliabilities. The paper closes with a summary of the important contribution to be made by multiplex electric machines, well as the advancements necessary for green VTOL aircraft sub-systems, e.g., power control unit and batteries, to improve reliability predictions and safety further