Eric Raymond is flying across Europe in an aircraft powered by the sun's rays to prove that "solar airplane" is not an oxymoron — but a viable means of air travel.
Raymond's eight-country tour of the continent in Sunseeker II starts Monday would be the first trans-European flight in a manned solar plane. The environmentally friendly aircraft developed by Solar Flight will highlight the potential for electric aircraft to shape air travel, and may even point to design efficiencies that could benefit fossil-fueled planes.
"If we can inspire people to re-examine the way they think about transportation and travel — to help them envision transportation modes that are not only cleaner and less destructive, but that provide a pleasant experience — then we will feel we've succeeded," Eric
Lentz-Gauthier, a member of the Swiss team, told Wired.com.
But, science and progress and greeness and all that aside, what's it like up there, soaring silently?
Incredible, said Lentz-Gauthier. Absolutely incredible.
"After a quiet takeoff and climb to a few thousand feet, you level off and throttle back," he said. "Then, with the sun at your back, you glance at the volt meter and see that it's ticking up instead of down.
That's when it really dawns on you that it is a new game you're playing with this airplane. It changes everything."
No one's saying you'll take a seat on a 747 sporting batteries and photovoltaic cells anytime soon. Battery weight and range remain the limiting factors for all but small aircraft. Still, electric aircraft are coming along. Start-ups like Pipistrel and Electric Aircraft build e-planes that work, and Boeing is experimenting with hydrogen fuel-cell aircraft. A venture called Solar Impulse hopes to test a sun-powered plane later this year.
The guys at Solar Flight say aircraft like theirs also provide insight into maximizing efficiency and minimizing weight that could make fossil fuel-burning planes a little cleaner and greener. Perhaps more than that, they get people thinking about new ways of propulsion.
Sunseeker II
weighs a whisper-light 292 pounds (506 pounds fully loaded) — about the same as an average motorcycle weighs. It's 23 feet long and has a wing span of 17 feet. Four lithium polymer batteries stashed in the wings provide power to an 8 horsepower motor for takeoff and climbing. Once the plane hits cruising altitude of around 3,000 feet, Sunseeker II uses solar power to maintain altitude. Open 'er up and the batteries drain in just 15 minutes, but Raymond says they'll recharge in 30 to 45 minutes.
The plane is capable of 40 mph under solar power and twice that with the batteries, speeds that are fast enough to make things fun, but slow enough to fly with the canopy open.
"You really feel like you are out there when there is no plastic to look through and you can feel the wind going by," Raymond said.
Sunseeker II has done more than 60 flights of an hour or more since its debut in 2002 — more, the company says than any other solar airplane. The plane is an improved version of Sunseeker I, the Raymond-designed plane that first took to the skies in 1989. Raymond took the plane as high as 16,000 feet and flew it across the United States during a 21-stop tour in 1990 that saw the plane spend 121 hours in the air.
"With Sunseeker I, powered performance was very limited, so you had to be crafty about finding updrafts," Raymond says. "Most of the time I flew it as an ultralight sailplane, with the motor off and the propeller folded."
It's an different game with the Sunseeker II, which was a featured attraction at Germany's AERO Friedrichshafen general aviation expo this week. It starts the European tour on Monday, with stops in Germany, Switzerland, Austria, Hungary, Slovenia, Italy, France and Spain. If all goes according to plan, it will be the longest trip
Solar Flight has made since Sunseeker I flew across the United States on a 21-stop tour in 1990.
The new plane features several improvements over Sunseeker 1, including a more efficient tail design, a full complement of navigation and soaring instruments and lithium polymer batteries instead of nickel cadmium. Larger wings mean more surface area for the solar cells, and this time around they're embedded in the wings rather than stuck on top. As a result, the plane can operate continuously on solar power when the weather is good. The engine's also bigger, climbing from 2.5 horsepower to 8.
"I tend to use the batteries to get to a high altitude, like 10,000 feet, and then fly level on direct solar power, often above the clouds," Raymond says. "At that altitude the air is cool enough that the electronics and the motor are well-cooled, the sun is bright and the air is smooth, so I can just cruise. The entire powertrain in the Sunseeker II is much more robust, so I am comfortable using it full time, more like a normally powered plane."
Much of Raymond's work is inspired by the late Gunther Rochelt, who designed and built the Musculair 1, a pedal-powered plane that broke speed records in 1984 when it reached a speed of 22 mph. Raymond was impressed at the speed and efficiency with which Rochelt built the plane, and he became obsessed with Rochelt's drive to make everything about his aircraft as efficient as possible — lessons he has incorporated into Sunseeker II.
"Every piece of the aircraft is optimized to do its job, both structurally and aerodynamically," Raymond said.
Raymond and Lentz-Gauthier concede the transition to electric flight will be slow, but insist it has already started.
"There are several pure electric self launching sailplanes that are available on the market today," Lentz-Gauthier said, "and I'm sure there will be more coming down the line."
Photos: Solar Flight. They've launched a website where you can track the progress of Sunseeker II's European tour.
Video: YouTube / AvWeb
See also:
- Electric Airplanes Take Flight. Get Yours Now
- Plug and Fly: The Battery-Powered Plane Makes Its Debut
- Solar Plane Test Flights Coming Next Year
Above: Sunseeker II was exhibited at last week's AERO Friedrichshafen show in Germany.
Above: This shot of Eric Raymond being interviewed at AERO Fredrichshafen gives you a sense of how big (or is that small?) the craft is.
Above: The plane's passenger had this view during a flight from Solar Flight's home airfield in Buttwil, Switzerland.
https://www.youtube.com/watch?v=WcWSI03NKo0
