Aircraft superconducting electrical propulsion system

An aircraft superconducting electrical propulsion system comprising an electric motor 104 configured to drive one or more propulsors 102. Each electrical motor is doubly (fully) superconducting, having superconducting stator (106, figure 7) electrical windings and super conductor rotor (108) electrical windings. The system comprises at least one closed reverse Brayton cycle cryocooler (optionally two recuperative cycle cryocoolers, see figure 6) operable on a working fluid (e.g. helium or hydrogen) configured to cool the electric motor 104. The cryo-cooler comprises a thermal accumulator 136 comprising a heat storage medium (e.g. aluminium, lithium, nitrogen or methane) having a higher volumetric heat capacity (VHC) than the working fluid. The cryocooler may comprise in fluid flow series, a compressor, heat exchanger in thermal communication with a heat sink, a turbine and a second heat exchanger configured to exchange heat with at least the electric motor. Figure 3 illustrates alternative thermal accumulator positions A, B, C, D in the cryocooler. The thermal accumulator may meet peak energy demands (e.g. during take-off, see figure 4).