Greased Lightning GL-10 Successful Transition Test - Published on Apr 30, 2015 NASA Langley researchers designed and built a battery-powered, 10-engine remotely piloted aircraft. The Greased Lightning GL-10 prototype has a 10-foot wingspan and can take off like a helicopter and fly efficiently like an airplane. In this video, engineers successfully transition the plan from hover to wing-borne flight in tests at Fort A.P. Hill in Virginia.