First flight for student-built electric Sling

The all-electric aircraft e-Sling has taken off for the first time.

The four-seater was developed and assembled by 20 students at ETH Zurich over two years at Innovation Park in Dübendorf, Switzerland, as part of their studies towards their bachelor degrees.

The white aircraft decorated with lightning bolts took to the sky for the first time Sept. 30, 2022, with the students watching from the sidelines.

“Being able to build an airplane during your university studies and then actually seeing it fly is an indescribable feeling,” said Anna Thumann, a student who worked on the project.

The project started almost three years ago. Carlo Schmid, a former world record holder for circumnavigating the globe as the youngest pilot to fly solo, dreamed of a sustainable, battery-powered small aircraft in Switzerland. When he approached ETH with his idea, the project was quickly initiated by the university.

It became a focus project — in which students independently develop a product — for mechanical and electrical engineering students to build an all-electric homebuilt.

The students, who used a Sling TSi as the airframe, develop the all-electric powertrain themselves.

Starting in 2020, a 12-member team of students developed all the components for the powertrain, including two wing batteries with a cooling system, as well as the inverter and the electric motor.

The biggest challenge in aviation is weight, so the students designed their components to be as energy-dense as possible, according to university officials.

A second student project team took over e-Sling in the fall of 2021. The aircraft was nearly finished, but all the different systems were not yet working together.

First, the entire powertrain, detached from the rest of the aircraft, went through thorough testing. After being improved, it was reinstalled in the aircraft.

Total system tests on the ground quickly followed, and in the summer of 2022, the aircraft was approved by the Federal Office of Civil Aviation (FOCA) in the homebuilt category.

Over those two years, the students raised 2 million Swiss francs in sponsorships to finance development of the aircraft and the set-up of the workshop.

Next step: A battery-hydrogen aircraft

With its successful first flight, e-Sling takes an important step towards sustainable aviation, according to the students.

However, this is only the beginning. This summer, the students founded their own association called Cellsius, which will continue researching electric powertrains for aviation.

To improve the range of electric aircraft in the future, the students developed a prototype of a hydrogen fuel cell system last year during the completion of the aircraft.

The use of hydrogen seems promising, as it has a significantly higher energy density than the installed batteries, they noted.

This system is now in the hands of the next generation of focus project students, who took over the project just in time for the start of the semester in mid-September.

Their goal is to combine the know-how they have built up from the battery-powered aircraft and the hydrogen-based project, to develop a powertrain for a battery-hydrogen aircraft. This will enable emission-free flying with increased range in the foreseeable future, the students say.

For more information: Cellsius.aero