Reference Technologies has designed the Hummingbird UAS which uses both multi-rotors and ducted fans for VTOL capabilities and manoeuvring. The Hummingbird boasts flight times in excess of 5 hours and can lift payloads over 25 pounds, and comes in three flavours: an electric model, a hybrid gas/electric, and a larger model that uses eight external rotors in conjunction with a 24″ central ducted fan.
Source: Engineering TV