Airbus and Siemens have designs on making hybrid aircraft a common sight on the world’s runways by 2035.
Much like the hybrids seen every day on our roads, hybrid aircraft would combine a small combustion jet engine with a battery and an electric motor to drive the propellers potentially using 50 percent less fuel than a conventional engine of the same output.
The Airbus/Siemens alliance is planning on launching a civilian hybrid aircraft by 2035 with a capacity of 90, similar in size to the short haul A318. However, before construction can start on a craft of that size the technology needs to be proven.
Frank Anton, Head of eAircraft at Siemens Corporate Technology
Image courtesy of Siemens
To that end Siemens has developed an electric motor weighing 50kg and a continuous power output of 260kW. Coupled with a small jet engine, the motor can be fitted to a four person aircraft with a take-off weight of two tonnes.
Where the technology gets interesting for those on the ground is the general lack of noise the hybrid engine will create. Using purely electric motors for take-off will only generate some noise from the propeller which can be further reduced by making the propeller larger and therefore being able to turn it more slowly. Coupled with other emerging technologies such as the morphing wing developed by NASA, living near an airport may no longer by the curse it once was.
The motor developed by Siemens has a power-to-weight ratio of 5kW/kg which is five times higher than a normal industrial motor giving it considerable power during take-off and climb and reduce the size of engine required for cruising. Furthermore as the motor could drive the propeller directly this offers greater flexibility when distributing the propulsion system around the aircraft.
To reduce the weight of the motor, the device’s four permanent magnets are arranged next to each other in such a way as to ensure that the orientation of each field is in a different direction. This arrangement, known as a Halbach Array, allows the magnetic flux to be directed so as to achieve the highest power output with minimal use of material.
To keep down the weight of the motor’s cooling systems, Siemens used direct-cooled conductors. Any heat lost from the copper conductors is discharged directly into an electrically non-conductive cooling liquid, such as silicone oil.
A great deal of work is going on among the research community and industry to improve the power densities of electric motors as high power density and torque density are critical because you can get more power. Just as is true with conventional engines, weight saved is fuel saved.
Another way Airbus and Siemens are working to reduce fuel consumption, and with it cut pollution, is to develop electric motors for the aircraft’s wheels. The system, known as EGTS, is powered by the aircraft’s auxiliary power unit (APU). At present a plane moves along runways using the main engines at idle speed which is very noisy and very fuel inefficient, not to mention blanketing the airport and surrounding area in pollution. This simple change to the plane’s design could prove critical in reducing emission levels and save significant amounts of fuel.
Having enjoyed a decade long relationship with Airbus we’re actively seeking candidates for roles across all facets of the organisation. If you’re interested in working with Airbus on this or other projects, register your CV with us today.