Slashdot Mirror
Solar-Powered Ultralight To Try 24-Hour Flight
blair1q writes "When the solar aircraft Solar Impulse lifts off from an airfield in Switzerland on a sunny day at the end of June, it will begin the first ever manned night flight on a plane propelled exclusively by power it collects from the sun. Former Swiss Air Force pilot Andre Borschberg and round-the-world balloonist Bertrand Piccard developed the aircraft, and Borschberg will be the pilot for this mission. 'The flight will require a lot of attention and concentration — the plane doesn't have an auto-pilot, it has to be flown for 24 hours straight.' For him, the most exciting part of the venture is 'being on the plane during the day and seeing the amount of energy increasing instead of decreasing as on a normal aircraft.'"
What everyone seems to ignore is that ridge lift has little to do with thermals.
Thermals are streams of warmer air rising up through colder air and caused by temperature differences, just as the parent mentions.
Ridge lift on the other hand is caused by wind encountering a slope and having to move up to get over it, thus creating an upwards vector that can be used by gliders to soar.
The wind that creates ridge lift is of course ultimately caused by air moving in to balance pressure differences, which are formed by air being displaced by temperature differences, but that doesn't mean that ridge lift is the same thing as a thermal.