Mission energy based modelling to assess the performance and feasibility of battery powered aircraft retrofit: a case study of the BN-2B-26 Islander in Scotland

This study develops a mission energy based framework to assess the performance and technical feasibility of retrofitting an existing commuter aircraft with battery-electric propulsion. The Britten-Norman BN-2B-26 Islander is selected as the case-study air-craft for selected domestic routes in Scotland. A MATLAB based parametric assessment framework was developed to evaluate aircraft and feasibility of selected routes. And it integrates key design parameters including power, energy, battery system, operations and payload. The results show that battery specific energy is a dominant technology parameter, while specific power, available installation volume, and retained payload determine whether the resulting configuration is practically feasible. For a 50 km mission, increasing battery specific energy from 400 to 1000 Wh/kg reduces the required battery mass fraction by approximately 60%. The energy available is around 57.6% of the nominal energy after deducting battery operational, regulatory and fixed mission energy requirements. Matching the baseline aircraft capability of approximately 774 kg payload over 998 km would require about 6050 Wh/kg and 2840 Wh/L of battery technology. Route assessment indicates that high payload cases are infeasible, while reduced payload cases can support wider short route coverage under future battery assumptions. Overall, the results indicate that battery-electric retrofit is most feasible for short-range commuter operations with reduced payload demand.