Superconductivity for aircrafts?
NASA recently published plans for the development of aircraft using superconductivity for a time frame around 2030. This could allow for noise reduction, improved carbon footprint and energy savings. The main advantage of HTS machines is that they have power densities similar to those of gas turbine engines but are potentially three times lighter than turbine engines. The project would entail the high speed turbine driving a generator that could electrically power a slower speed motor connected to the fan. This could enable the decoupling of the turbine and the fan that imposes stringent technical limits on current civilian jet aircraft, in terms of fan tip speed and noise reduction. However, alternative current (AC) losses in HTS superconductors must be reduced in such turbines for them to become practical. Another question is how to provide the necessary cryocooling without significantly reducing the power density of the overall superconducting and cooling system? The option of using liquid hydrogen as fuel and as a cryocoolant has been considered, but poses the problem of larger fuel tanks. In order to meet specific weight and efficiency targets, a 10 kW cryocooler should weigh less than 500 kg, which is an ambitious goal that could become easier to achieve if the refrigeration load were reduced by significant reductions in the AC losses of HTS materials. Given the technical challenges, 2030 may be a short deadline.