A solar-powered aircraft will attempt an around the world flight beginning sometime after March 1, 2015, according Bertrand Piccard, president of Solar Impulse, the Swiss firm that built the aircraft. The Solar Impulse 2 (SI2) is a larger, faster and more advanced version of the original Solar Impulse, which flew from San Francisco to New York in 2013, after a series of test flights in across Europe and Africa from 2009 to 2012.
The purpose of the impending mission – which is a cross between a proof of concept and a publicity stunt – is to demonstrate the possibilities inherent in sustainable fuels such as solar energy, according to a televised press conference during yesterday’s unveiling of the solar-powered plane. The mission may also have that practical purpose but, as a publicity stunt, it has already been an overwhelming success, making Solar Impulse synonymous with “solar-powered flight.”
The media hoopla generated by yesterday’s unveiling obscured the salient fact that another company, Solar Flight, has been in the solar-powered aircraft business since 1986. Its SunSeeker completed a solar-powered flight across the United States in 1990. No references to Solar Flight have appeared in the media coverage of the unveiling, despite the fact that Solar Impulse 2 is using technology developed by Solar Flight. When reached for comment about the apparent discrepancy, industry analysts have said that Solar Impulse is “very good at communication.”
Several news organizations have been reporting that Solar Impulse is attempting a non stop flight around the world. Fox News has reported that the SI2 will complete its mission in five consecutive days. Neither statement is true.
The airplane itself could easily make it around the world without stopping With an operating ceiling of 27,900 feet, the SI2 will always be able to find some sun to bask in during daylight hours by flying above the clouds, while using sophisticated polymer batteries to remain aloft at night. With a cruising speed of 43 mph, however, the SI2 would take 613 hours to circle the earth.
Solar Impulse 2 does not have sufficient payload capacity to carry enough food, water, and air to sustain the pilot for a 25 day journey. Instead, the aircraft will land every few days to allow the two pilots, Piccard and Solar Impulse chief executive officer Andre Borschberg, to replace each other for successive legs of the mission, and to restock the aircraft with supplies.
The first recorded aerial circumnavigation of the Earth is credited to the United States Army Air Service, which completed the feat in 175 days in 1924. Not to be outdone, the German Graf Zeppelin took 21 days to complete the first nonstop circumnavigation by an airship in 1929. In 1949, a United States Air Force B-50 Stratofortress circled the Earth nonstop in 94 hours on a mission that required four mid-air refuelings.
In 1986, co-pilots Dick Rutan and Jeana Yeager flew brother Burt Rutan’s Voyager aircraft around the world non stop in just over nine days. In a 1992 publicity stunt, an Air France Concorde circled the earth in 32 hours and 49 minutes, but the fuel-guzzling supersonic jet liner had to land six times to refuel. In 1999, Solar Impulse president Piccard, a psychiatrist by training, and co-pilot Brian Jones circled the earth in a hot air balloon in just under 20 days. On March 3, 2005, another Burt Rutan designed airplane, the jet powered Virgin Atlantic GlobalFlyer, completed a nonstop round the world flight in just 67 hours, with solo pilot Steve Fossett at the controls.
The four engine, experimental SI2 has the same 208 foot (63.4 meters) wingspan as the Airbus Super-jumbo A380 but weighs only 3,500 pounds fully-loaded, around the same as the average family car. The carbon fiber materials used in the construction of the aircraft weighs only one-third as much as piece of paper of the same size.
The long-distance capabilities of the Solar Impulse aircraft far outstrips any current American military aircraft. The Lockheed U-2 high altitude spy plane, has a maximum range of only 8,000 miles (15,000 km) and a flight endurance time of 12 hours. Predator drones have a range of 675 miles, and flight endurance times of 24 hours. Reapers have greater range, 1,151 miles but only 14 hours of lurking time. The Solar Impulse has unlimited range and duration.
The military applications of an aircraft that can “remain on station” indefinitely are very real. Adoption of solar-powered aircraft by the military will hinge on durability and cost. The Solar Impulse designs are technically sophisticated, cutting edge stuff. Technical sophistication, however, often comes at the expense of durability, which remains an unknown factor with solar aircraft. That is why the proof of concept is needed to silence the critics.
The other major difference is cost. So far, the Solar Impulse project has spent around $124 million, for which the company now has two aircraft, making the per unit cost $62 million each. Counting maintenance, the U2 spy planes cost $50 -$70 million each, depending on the specifications. Reaper drones cost $12.5 million each, according to Time Magazine. Predator drones are cheap at $4.5 million per unit.
There are very few non-military practical applications for solar power aircraft that can remain aloft indefinitely….but Facebook CEO Mark Zuckerberg thinks he has found one. He is betting $60 million on his purchase of Titan Aerospace, hoping to put 11,000 solar-powered drones to work providing WiFi access points for Facebook customers in an attempt to compete with internet service providers for monthly access fees.
More than cash flow is at stake. Both Facebook and Google have been looking for ways to minimize their exposure to adverse actions by internet service providers such as Comcast, which have the ability to throttle back on the download speeds for specific websites, as Comcast had been doing with Netflix.
Google gurus Larry Page and Sergey Brin have already bet a bundle on Project Loon, which uses Helium filled balloon to carry WiFi access points. They may be hedging their bets, however, by supporting this solar-powered aircraft project, just in case the balloons break, in which case Google already has a foot in the door at Solar Impulse.
By Alan M. Milner