On Aug. 19, National Aviation Day, a lot of people are reflecting on how far aviation has come in the last century. Could this be the future – a plane with many electric motors that can hover like a helicopter and fly like a plane, and that could revolutionize air travel? Engineers at NASA's Langley Research Center in Hampton, Va., are studying the concept with models such as the unmanned aerial system GL-10 Greased Lightning. The GL-10, which has a 10-foot wingspan, recently flew successfully while tethered. Free-flight tests are planned in the fall of 2014. This research has helped lead to NASA Aeronautics Research Mission Directorate efforts to better understand the potential of electric propulsion across all types, sizes and missions for aviation.