30 July 2002
30 July 2002
Twelve miles high, an unmanned, solar-powered aircraft could provide telecommunications companies with a platform for delivering a host of wireless services for the next generation of mobile devices.
SkyTower Inc. said it's successfully tested the equipment and the idea and hopes, within three years, have the unmanned craft aloft over the major cities of the United States to demonstrate the technology. The system would establish a new, high-altitude wireless communications base, providing clearer transmissions by bringing satellite technology closer to Earth, but keeping it high enough to avoid ground interference such as buildings and trees.
Developers of the technology said it will provide higher bandwidth, letting users videoconference with PDAs or download files from the Internet five times faster than cable modems or DSL connections -- all at a fraction of today's cost. ``If it works, there's obviously a market for it. But the big question is if,'' said Jeff Kagan, a private telecommunications industry analyst in Atlanta. ``There's no other company to look at to said, 'Hey, the model works.' ``This is when you have to take a leap of faith.''
SkyTower recently tested the equipment aboard a NASA-developed prototype plane 65,000 feet above the Hawaiian island of Kauai. The tests involved beaming signals for mobile phones and handheld devices and transmission of a high-definition television, or HDTV, signal to the prototype plane Pathfinder-Plus, a smaller version of the aircraft that SkyTower hopes to eventually use for their system.
``It's similar to HDTV transmission that's being explored here now in the United States, but with twice the resolution,'' Hindle said. ``Because of that unique position in the sky -- essentially a 12-mile tall tower -- it provides better coverage than satellites and terrestrial towers.'' But the technology also could be used by government agencies to monitor natural disasters like hurricanes and assist emergency services, Hindle said. ``They could launch an airplane and have instant backup communications,'' he said.
``We expect that within 10 years we can have thousands of airplanes in the sky over the major cities of the world,'' said Matt Kobayashi, director of Asia-Pacific business development for AeroVironment. ``Development of the plane is basically finished.''
AeroVironment developed the solar-powered Pathfinder-Plus and Helios prototypes with NASA's help. The $15 million Helios, which looks more like a flying wing than a conventional plane, reached an altitude of 96,500 feet during a nearly 17-hour flight from Barking Sands on Aug. 13, 2001. The altitude, about 18 miles, was considered a record for a non-rocket powered aircraft. The remote-controlled Helios -- made of carbon fiber, graphite epoxy, Kevlar, plastic foam and a plastic skin -- is extremely flexible, lightweight and durable. Its 14 specially designed propellers are driven by small 2-horsepower motors powered by 65,000 solar cells covering the wing. Its 247-foot wingspan is greater than that of a Boeing 747, yet is only 8 feet from front to back. Its cruising speed ranges from 19 to 25 mph.
Hindle saids the next step in development is testing a fuel cell that allows the solar-powered plane to stay in the air overnight. That demonstration is expected sometime next year.