On Monday, two Swiss pilots will embark on a five month journey to fly around the world in a solar-powered plane. Set to take off from Abu Dhabi, the plane will head first to Oman, then India. From there, the Solar Impulse 2 will cross several continents and two oceans in its campaign to not only set a world record for the longest, manned solar-powered flight, but also to raise awareness about the viability of alternative energy.
Bertrand Piccard, one of the plane’s pilots who is also the company’s chairman, says, “We want to demonstrate that clean technology and renewable energy can achieve the impossible. Renewable energy can become an integral part of our lives, and together we can help save our planet’s natural resources.”
What’s so special about this solar-powered plane?
The Solar Impulse 2 is an upgraded version of the original Solar Impulse plane, which set eight world records, “including the longest solar powered flight, the first solar plane to fly between two continents and the first solar plane to fly through the night.” The Si2, on the other hand, will be the first solar-powered plane that can stay in the air for five consecutive days and nights without the need for fuel. As a result, pilots Bertrand Piccard and Andre Borschberg will take turns flying the single-seater Si2.
The Si2 has a 72-m (236ft) wingspan that’s fitted with 17,248 solar cells that also stretch across the plane’s fuselage and tailplane. Each cell can collect up to 340kWh per day of solar energy that together powers four 17.5 horsepower electric motors. These cells are also responsible for recharging several lithium polymer batteries, which activate at night to help the Si2 continue flying.
Although the wingspan of the Si2 is wider than a 747 jumbo jet, the plane only weighs 2,300 kilogram (5,070lb). Despite all of its solar cells and lightweight construction, the Si2 can only “fly at speeds of between 36 kph and 140 kph (22 mph and 87mph).” While a typical commercial airliner requires around 500 hours of flight time to travel around the world, it’s going to take the Si2 months to accomplish the same.
The Si2’s cockpit is only 3.8 cubic metres in volume with no heating or air conditioning available. The flight requires plenty of physical endurance and stamina as each pilot can only take 20 minute cat naps every two to four hours. It’s also not certain if the plane will in fact be able to successfully cross the Atlantic and Pacific oceans. Although computer generated simulations suggest the distance can be overcome, the actual flight depends on the right weather conditions.
As impressive as this solar-powered undertaking is, the technology is still far from being a practical one for current airliners. Deputy editor of Aerospace magazine, Bill Read, explains that solar flight is “not yet even remotely ready for any applications in commercial flights. Currently, an aircraft entirely covered in solar cells would not be able to generate enough power to enable it to fly. The Solar Impulse is only able to fly using solar power because it is specially constructed to be very light weight and with a huge wingspan. Unless there is a quantum leap forward in solar cell technology, solar cells cannot yet be considered as a sole power source for aircraft.”
Still, solar-powered technology is advancing quickly and while powering a jumbo jet using solar power is not yet feasible, Borschberg is quick to point out how his team’s engineering feats already benefit other applications, “To fly with the sun, day and night, we had to build an aircraft that is extremely energy efficient. These technologies that provide energy efficiency can be used in your home, in your car, in the appliances that you buy. With these technologies we can cope with a major part of the challenge we are facing today in terms of energy, environment, pollution, natural resources and so on.”
Check out the video overview courtesy of Solar Impulse: