The electrification campaign for rotorcraft is not as mature as that of commercial aircraft and requires significant architectural changes. Scientists are developing a fully electric replacement for the current mechanical–hydraulic rotor brake system with EU funding of the project 'Helicopter electric regenerative rotor brake' (HERRB) . The HERRB system will recover energy normally dissipated as heat from the rotating blades to provide controlled regenerative deceleration of the main and tail rotors. This unit could also be used as an electrical generator during flight, enabling electrically assisted start-up and controlled auto-rotation in the case of engine failure. Critical to feasibility is minimisation of weight while maintaining the required reliability and safety. During the first reporting period, scientists developed the necessary specifications and modelling tools. This was used to design and optimise the dynamic (regenerative) rotor brake and the electric static (or holding) brake. Scientists will then construct the prototype to characterise its performance on a full-scale test rig that closely simulates the electrical, mechanical and thermal environment of operation. HERRB technology should significantly advance the state of electrical rotorcraft technology demonstrators with a prototype regenerative braking system. This will reduce rotorcraft weight while enhancing performance, improving overall fuel efficiency and reducing emissions for greener and safer rotorcraft.