With the intention of being the first aircraft to circumnavigate the world on solar power, the folks at Solar Impulse have unveiled their designs for the Solar Impulse Alpha. The 4 engine aircraft is being built to demonstrate the ability to fly a full 36 hours, proving it capable of staying aloft through a full day/night cycle. While not the first solar aircraft around, it's probably the most ambitious project to date. The group is targeting a circumnavigation by 2011, with test flights for the Alpha design set to begin in 2009. Mark your calendars as we're bound to see coverage of these flights, especially with the current global interest in renewable energy technologies.