NASA Langley Research Center has developed Greased Lightning, the first unmanned aerial vehicle (UAV) that combines vertical take-off and landing (VTOL) capability with long-endurance flight. Previously, these two capabilities were considered mutually exclusive; for example, helicopters offer VTOL capability, yet are inefficient for long-endurance travel.
The UAV market is large (multi-billion USD) and growing, with a global reach and many regional markets. This presents numerous opportunities and entry points for a new and superior UAV technology. The core technology that enables the Greased Lightning UAV is the aerodynamic efficiency it achieves in its cruise configuration. Electric motors at each propeller negate the need for drive shafts and gearing, enabling this distributed electric propulsion (DEP) aircraft configuration. The design is intended to utilize a hybrid electric drive system that includes small diesel engines that drive alternators to power the electric motors and charge an onboard battery system. The batteries provide the power boost needed for VTOL and hovering.
Numerous other novel design elements are incorporated, such as folding propellers to minimize drag when not in operation so the propulsive efficiency can be nearly ideal at both hover and wing-borne flight conditions.