HTS-Technology for hybrid electric aircraft

The world of transportation is in a transition: From combustion engines to electric machines. This change is getting more and more momentum on the land, on the sea and in recent years also in the air. On the one hand, electric aircraft is supposed to open absolutely new opportunities for urban mobility with such concepts as prosed and currently heaviliy investigated by Uber, Vahana, CityAirbus or Lilium. On the other hand electric aircraft and in particular hybrid electric aircraft will allow to reduce the COx, NOx and noise emissions as required by the ACARE 2050 goals. Although demonstrated by several proof-of-concepts maiden flights by Siemens in close collaboration with Diamond Aircraft, Magnus and EXTRA that hybrid electric flight is possible, there are many technical challenges on the road to the entry into service of hybrid electric regional jet. Siemens and Airbus have a started collaboration in June 2016 to adress jointly this challanges and make a large step towards this ambitious goal. The challenges relate mainly to the weight and efficiency of electric propulsion components. Motors and generators at the multi-MW scale have been available for industrial applications for a large time - however at such weights that render flying with them impossible. With a power-to-weight ratio of around 0.5 kW/kg traction drives for motors or ships are significantly heavier than gas turbines which have a typical power-to-weight ratio of about 5 kW/kg to 9 kW/kg. With the SP260D Siemens Aircraft developed a electric propulsion direct drive motor with power of 260 kW and a weight of roughly 50 kg, therefore a power-to-weight ratio of about 5.2 kW/kg which is the currently world record. For doing so we went to the edge of magnetic, mechanical, thermal and electric properties of materials and involved numerical optimization to be as lightweight as possible. Nonetheless we need to take an additional big step. How to go even further with lightweight electric machines? An immense opportunity could offer high tempereratur superconductors as they allow far higher airgap magnetic fields than the best NeFeB magnets and much higher current densities in the stator. In this talk I would like to adress in how far superconductivity could allow to significatly increase the power-to-weight ratio of hybrid electric propulsion systems and therefore be a key technology for hybrid electric aircraft.