This is a previously unreleased video from the ANN archives.
Jack Langelaan, Pipistrel Team Leader and engineering professor at Penn State University explains the Green Challenge. The NASA Green Challenge was to design, build, and fly an airplane that gets 200 passenger miles per gallon of fuel at 100 mph. To this into perspective, a Cessna 172 with four people aboard gets about 60 passenger miles per gallon of fuel.