Although the armed forces have been slow to adopt them, more and more helicopter UAVs are appearing on the market. The latest is the Fire-X, which will be based on the 2.7 ton Bell 407 manned helicopter. Bell-X is being developed by the same outfit that produced the Fire Scout. Fire-X will use a lot of technology from Fire Scout. While the military has been slow to adopt helicopter UAVs, there is sufficient interest to keep the manufacturers at work on new models.
But the military has not had a lot of success with helicopter UAVs. Recently, the U.S. Army cancelled its RQ-8B Fire Scout UAV (unmanned aerial vehicle) project. It just didn't work out. The two ton Fire Scout is based upon the Schweitzer 333 unmanned helicopter, which in turn is derived from the Schweitzer 330 commercial lightweight manned helicopter. The U.S. Navy remains interested in Fire Scout, and they have developed, and put into use, their own RQ-8A version. The RQ-8B died because the army already had plenty of UAVs that got the job done. The navy kept Fire Scout because helicopters are more practical on most navy ships (for landings and takeoffs.) A navy Fire Scout just completed several months of successful use on a frigate (in both the Atlantic and Pacific).
Another helicopter manufacturer, Kaman, modified its K-MAX manned helicopter to meet U.S. Marine Corps requirements for a supply helicopter UAV. The resulting Kaman K-MAX UAV is a 5.4 ton helicopter with a cruising speed of 148 kilometers an hour and an endurance of over six hours. It can carry up to 2.7 tons slung underneath.
Already out there for over a decade is the A160T, a three ton helicopter, able to fly under remote control or under its own pre-programmed control. It is based on the Robinson R22 manned helicopter. It has a top speed of 255 kilometers an hour, and was originally designed to operate for up to 40 hours carrying a payload of 136 kg (300 pounds).
There are some smaller helicopter UAVs, that are not based on commercial vehicles.