The Solar Impulse 2 (Si2) aircraft has taken off from Cairo, Egypt, for the last leg of its round-the-world journey, which will end in Abu Dhabi, UAE.

Currently being piloted by Solar Impulse initiator and chairman Bertrand Piccard, the single-seater aircraft is scheduled to reach Abu Dhabi after a flight lasting two days and two nights.

Exclusively powered by solar energy, Si2 is the first aircraft of its kind that is designed to fly day and night without using traditional fuel.

Piccard said: “It’s very emotional to take off from Egypt with Si2, given that I landed here in 1999 after accomplishing the first non-stop round-the-world balloon flight.

“It’s precisely here that started my dream of making another circumnavigation, but this time without fuel, only on solar power."

“Today, we are living the final moments of a once in a lifetime adventure contributing to setting a new milestone in aviation."

Along with Piccard, Solar Impulse CEO and co-founder André Borschberg has also been taking turns in piloting the Si2 around the globe.

Borschberg said: “Today, we are living the final moments of a once in a lifetime adventure contributing to setting a new milestone in aviation, one centered not on speed or height, but instead on exploring new clean and efficient technologies that can almost make it possible for the plane to fly with unlimited endurance, a week, a month; something that was never done.”

Made of carbon fibre, Si2 has a wingspan of 72m and is equipped with 17,248 solar cells, which are built into the wing power the four batteries that subsequently power the four electric engines.

Before embarking on its final stretch of journey, the aircraft landed in Egypt after a flight of two days and two nights, crossing Mediterranean Sea from west to east and covered a distance of 3,745km.

Image: Si2 takes off for the final leg of its around-the-world tour. Photo: courtesy of Solar Impulse.