Read more about the solar airplane "Solar-Impulse HB-SIA"
Piccard comes from a famous family of adventurers. His father, Jacques, is considered an important pioneer of deep sea research. His grandfather, Auguste Piccard, was a physicist and an inventor as well as the first person to reach the stratosphere in a balloon.
Chances are good that grandson Bertrand will also make history. Solar Impulse HB-SIA, the first prototype of the novel airplane, was built between 2007 and 2008. Regular test flights have been taking place in western Switzerland since December 2009, while at the same time the airplane is being continuously optimized. Construction of a second prototype will begin shortly. The round-the-world flight is currently scheduled for 2013 and will comprise five stages, each lasting five days.
The final model will represent a completely new technology. Its fuel tank is the sun. More than 10,000 silicon solar cells mounted on the surfaces of the wings produce the electricity that powers the airplane and keeps it aloft. A portion of the energy generated during the day is stored in lithium-ion batteries so that the airplane can continue to fly throughout the night.
The solar energy is fed into four electric motors, each of which has a peak output of 10 hp. The solar plane has a ceiling of around 9,000 meters and can withstand temperatures between minus 45 and plus 80 degrees Celsius.
The innovative solar airplane is both a giant and a dwarf.
The pivotal element, however, is the airplane’s weight. The heavier it is, the more energy it uses. It’s no wonder, then, that everything possible is being done to reduce its weight.
In Bayer MaterialScience, Piccard and Borschberg have found a partner that is a leader in this field. “Our technology is crucial for the success of the project,” says engineer Johannes Seesing. The primary focus is on the use of innovative material solutions to reduce the airplane’s weight and energy consumption.
The company’s experts have been working since March 2010 to continuously reduce the weight of Solar Impulse through sophisticated technologies and innovative products. The goal is to trim an additional ten percent from the current version’s weight of 1,600 kilograms. The company’s contribution takes the form of comprehensive technical expertise, high-tech polymer materials and energy-saving lightweight products (cf. graphic on pages 38 and 39). Baytubes carbon nanotubes, in particular, could improve the strength of the structural components while enabling an extremely low weight. Seesing points out that the bar is set high. “Solar Impulse will have the wingspan of a jumbo jet while weighing hardly more than a mid-size car.” Never before has an airplane been built that is so large yet at the same time so light.
During the day, Solar Impulse will fly at an altitude of 9,000 meters to make optimal use of the sunshine. At night the airplane descends to around 1,500 meters, where it can fly very steadily with the minimum expenditure of energy because the lift is greater at higher air pressure.
Special vibration device to counter microsleep
Because the current model does not include an autopilot, aviation pioneer Borschberg had to stay awake for the entire 26-hour flight. If he had dozed off, a special vibrating device would have woken him. “André and I will use meditation and self-hypnosis during the round-the-world flight,” says Piccard. In the future, an autopilot will allow the pilots to rest for at least a short time.
There are still a lot of questions to answer before then, however. One idea being considered, for example, is to recycle urine into drinking water on board because liquid storage tanks would make the airplane too heavy. “Every kilogram that the plane carries uses energy,” explains Piccard.
“I am convinced that they will succeed,” says Seesing, the Bayer expert. “They will fly – and actually circle the world!” But sometimes it takes small steps to make big dreams come true. The adventurers’ next step will therefore be to cross the Atlantic.