Solar Impulse begins final leg of epic round-the-world journey


The final leg of Solar Impulse’s record-breaking round-the-world flight is underway, with Swiss pilot Bertrand Piccard at the controls and expected to touch down in Abu Dhabi within 48 hours.

The aircraft left Egyptian capital Cairo late on Sunday night and will head over the Saudi Arabian desert before reaching its final destination in the UAE: an ostensibly serene journey made potentially troublesome by the high temperatures in the region at this time of year.

"We thought it was going to be an easy flight because it’s always good weather between Egypt and Abu Dhabi across Saudi," said Piccard. "But actually it’s extremely difficult to find a good strategy."

Air above the desert is warmer and thinner than the aircraft has hitherto been subjected to, meaning the plan’s four solar-powered motors will have to work that little bit harder to maintain forward momentum. And while the sun resource will not be a problem, much will rest on the lithium polymer batteries’ ability to fully charge while subjected to such intense heat.

To counter some of the adverse effects expected by the hot air, Piccard will cruise at a higher altitude than usual, and thus will require the use of an oxygen mask – which will also deplete the plane’s energy resources.

This final leg of the journey is the 17th flight of the tour, and history will be made provided the aircraft touches down safely, meaning Solar Impulse has made it around the world, traveling 30,000km, using not a single drop of fuel.

The setbacks there have been – damaged batteries, missed weather windows, pilot illness – have been relatively slight in the grand scheme of things, but success this week does not mean the end of the Solar Impulse experiment.

"The round-the-world flight ends in Abu Dhabi, but not the project," Piccard told Reuters. "The project is a big promotion of clean technologies around the world, and the legacy of Solar Impulse is the created international community."