Making its maiden flight, the GL-10 will hopefully be able to replace the helicopter one of these days down the road. Right now, the NASA-designed GL-10 Greased Lightning happens to be an unmanned hybrid-electric aircraft which is capable of swiveling not only its wings, but its engines as well, into the vertical position so that it can function as a vertical takeoff and landing (VTOL) aircraft. Thanks to the wonders of electric propulsion, it has paved the way for an efficient hybrid-electric aircraft design which might see it phase out the helicopter one of these days.
Efficiency is the key obstacle here where VTOL aircraft are concerned, and hopefully the advances made in due time from where the GL-10 left off will be able to usher in a new era in aviation.