They announced the VULTURE program last week which is an initiative to develop an airborne platform that is heavier-than-air and can remain aloft for 5 continuous years, this announcement is to potential offerors (or companies interested in contracting for some of the R&D).
This would be an exploratory development program with the overall goal to develop and demonstrate the ability to deliver and maintain an airborne payload on station for an uninterrupted period exceeding 5 years.
Note to you wannabe contractor geeks - the government is not interested in approaches that use either radioactive energy sources or employs any form of buoyant flight for this application.
The VULTURE Air Vehicle Program will research and develop technologies and systems which will enable the Military to deliver and maintain a 1000 lb, 5 kW airborne payload for an uninterrupted period exceeding 5 years with a 99+% on station probability. The architectures selected and the specific approaches taken by the Offerors will determine the range of technical areas that are developed, including, but not limited to, environmental energy collection, high specific energy storage, extremely efficient propulsion systems, precision robotic refueling, autonomous materiel transfer, extremely efficient vehicle structural design, and mitigation of environmentally-induced loads.
The real purpose of the project isn’t necessarily to develop a working prototype for the military, but rather, while working towards that goal they must research and develop individual technologies that, while they may lead to a prototype, will definitely lead to more robust aircraft technologies that can be integrated into current or future systems. It’s envisioned that this program will, at a minimum, develop and demonstrate advanced reliability technologies for air vehicles.