That looks like a Gulfstream. Gulfstream factory is in Savannah Georgia.
Most are built for private or corporate customers but some are built for military with a wide variety of special equipment fits.
Planes returned to the factory for overhaul or upgrading, or prototype development planes might complete a series of test flights.
Might also be prospective buyers going for a 'test drive' so to speak, rather like buying a car or truck.