Final leg of round-the-world journey beckons for Solar Impulse

ABU DHABI // Bertrand Piccard, the pilot and co-founder of Solar Impulse, will embark from Cairo at 2am UAE time on Sunday on the final leg of the round-the-world journey back to Abu Dhabi, where the Masdar-backed adventure first began its tour and clean energy campaign last year.

"With our thoughts caught up in the flurry of events and the Monegasque flags flying at half-mast, it has only now dawned on us that we need to move forward with this last flight on the round-the-world tour," the crew said on Saturday on its blog at solarimpulse.com. "Bertrand Piccard will takeoff with SI2 from Cairo, Egypt on July 16th at 22:00 UTC... Direction: Abu Dhabi. We are moved by this flight. A continuous criss-cross between thrill and sadness, we are finding it difficult to balance our emotions to prepare for our final landing with SI2 on this round-the-world tour."

The voyage across the Middle East is expected to take about 48 hours, and will not be without its own set of unique challenges.

“Crossing the Middle East is not as easy as you may imagine. There are a number of factors, such as no-fly zones, heat, thermals, takeoff and landing conditions, and wind making this flight the most complex we have yet encountered,” the crew wrote.

The hot weather conditions in the region will be a “big obstacle” for the solar-powered plane. When he reaches Saudi Arabia, where the thermals caused by rising heat reach up to 21,000 feet, Dr Piccard “will have to endure high altitude conditions in an unpressurised and unheated cockpit for a longer duration than usual.” Moreover, the electronics on board do not have an active cooling system and rely on the air to cool down.

“The highest heat SI2 will encounter on this flight is 35 degrees celsius at the landing in Abu Dhabi,” according to solarimpulse.com. “Due to the heat that comes from a Foehn wind originating in the Omani mountains, we have to land at nighttime in order to handle the temperature on the ground and due to wind conditions. We also need to consider the heat on the runway as we need to ensure the airplane is safe from the heat until it reaches the hangar.”

The flight will be accompanied by a live broadcast and a virtual cockpit where viewers can follow the flight path, energy level and pilot’s vitals on solarimpulse.com.