What would be your perfect hybrid aircraft?
It is important to understand that the primary reason for a hybrid aircraft is to permit the use of a distributed propulsion system. This takes away the design constraint of having to carry two (or more) high-bypass gas turbines. The design using hybrid is now free to exploit fully new low-drag designs with a much more aerodynamic airframe, for example. It also allows other aerodynamic improvements such as boundary layer ingestion (BLI), which again reduces drag. To achieve this a superconducting electric power system will be required which requires cryo-cooling; however this can also be achieved by using a cold fluid as a heat sink. This fluid can also be chosen to be a fuel as well once evaporated, such as liquid natural gas, which lowers emissions and costs less than jet fuel. However, in the future this could also be liquid hydrogen, which matches most superconducting materials and, of course, when burnt as fuel gives no CO2 emissions. Such an aircraft was used as the basis of a Cranfield study and this would be my ideal hybrid aircraft as shown below. Note that many other (less radical) versions are possible.
What recent advances have made superconducting power systems a more realistic prospect for delivering hybrid aircraft?
We have been working on superconducting power networks both theoretically and experimentally, in collaboration with other universities. The work has included studying the use of magnesium diboride (MgB2) as a superconducting material that is far easier to work with than other materials. We have also studied fault-current limiters (FCLs) and switching techniques that offer unique advantages for this approach and can remove many constraints traditionally associated with high-power networks.
Have you conducted any physical tests to substantiate your research?
We have worked closely with others in the use of MgB2 wire for FCLs, for example. This has included advanced tests and trials of these devices for energy networks where full-scale faults have been successfully carried out and monitored.
Professor Malkin leads the Electrical Power Group at Cranfield, investigating new application areas in Novel Energy and Transport Applications.
Professor Malkin will present ‘Hybrid-electric distributed propulsion aircraft superconducting power systems’ on Day 1 of the forthcoming Electric & Hybrid Aerospace Technology Symposium, in Bremen, Germany, 17-18 November, 2015.
Register now to secure your conference pass.