Since 2009 an Israeli firm has developed three versions of their Black Eagle helicopter UAV for military and civilian use. The original gasoline-powered Black Eagle 50 weighed 35 kg (77 pounds) including a three kg (6.6 pound) sensor payload and had a top speed of 130 kilometers an hour. Max altitude is 2,800 meters (9,000 feet) with endurance of three hours and the ability to operate up to ten kilometers from the operator. That was later increased to 150 kilometers. Payload was also increased to five kg (11 pounds) and endurance to four hours. Max altitude increased to 3,100 meters (10,000 feet) The only drawback was the engine generated noise, which made Black Eagle 50 unsuitable for missions requiring stealth. Basic sensor was a day/night stabilized vidcam. This could be replaced or augmented by ELINT (electronic intelligence) sensors that detected a variety of electronic signals. There was also a maritime patrol version including a synthetic aperture radar that detected objects below in any weather and provided a photo-like image and this could be augmented by an AIS (automatic identification system) transponder which all ships displacing more than 300 tons must carry. AIS provides detailed information on the ship. All Black Eagle UAVs are controlled by a laptop computer that allows the operator to create and modify flight plans plus directly control the UAV with a small joystick. There is also a map calibration feature which turns aerial photos into precise maps of what was recorded.
A decade later the silent electric powered Black Eagle 25E and 50E were developed. The smaller 25E weighed 25 kg (55 pounds) with a two kg (4.4 pound) payload and max endurance of 60 minutes. The 50E weighed 35 kg (77 pounds) with a 15 kg (33 pound) payload and endurance of 110 minutes.
More recently the Black Eagle 50H (hybrid) was introduced. This model used a gasoline engine and battery power. Payload is 12 kg (26 pounds) and endurance is five hours using the engine plus less than an hour using batteries. All electric and hybrid Black Eagles use composite/aluminum bodies and are built to operate from ships.
There have been several of these helicopter UAVs developed over the last two decades, but few have found steady work with the military. For example, the U.S. Army has had a hard time finding enthusiastic users for its RQ-16A helicopter UAV. Although it successfully tested this miniature helicopter UAV, originally called the MAV (Micro Air Vehicle), in Iraq, only the U.S. Navy ordered some (372). Theis 8.4 kg (20 pound) UAVs can fly as high as 3,300 meters (10,500 feet), and carry stabilized day/night cameras. The MAV is most useful in urban environments, where it can quickly flit around buildings and other obstacles. What attracted the navy order, and some interest in Britain, was the RQ-16As ability to assist EOD (Explosive Ordnance Disposal) troops who search for, and clear, roadside bombs in Iraq and Afghanistan. The RQ-16A, equipped with one downward looking vidcam, and one looking forward, can quickly go to suspicious objects, hover nearby and allow the UAV operator to get a detailed look. This is often all it takes. If not, a ground robot, with a robotic hand, can be rolled up, to pick at the suspicious object.
The MAV has its blades contained within a cylindrical enclosure, and uses software control to keep it stable in flight. All the operator has to do is tell it where to go. Endurance, as with helicopters, depends on altitude. At sea level, the MAV will stay in the air for about 40 minutes, before it has to be refueled with the same fuel as military vehicles. The UAV can operate up to 11 kilometers from the ground station, and has a top speed of about 1.5 kilometers a minute. It cannot operate if there is a wind of more than 28 kilometers (17 MPH) an hour.
When operating at 10,000 feet (typical in Afghanistan) it can stay in the air for only about 20 minutes. The MAV and control equipment can be carried in a special container which, when loaded weighs about 18 kg (40 pounds). It can be backpacked. The MAV costs about $35,000. A complete RQ-16A system consists of two UAVs and a ground station.
The MAV was designed in a more compact package, instead of just producing a miniature helicopter (like the Black Eagle 50). But even the more compact form factor did not overcome the resistance to helicopter UAVs.
The problem with helicopter UAVs is that the ability to hover, while useful, is not as important as being able to stay over an area for hours and hours, passing on video of what is going on down there. Fixed wing UAVs can do that more cheaply and reliably than can helicopter UAVs.
Black Eagle overcame a lot of those objections, in part by developing a number of Black Eagle versions, usually in response to military and civilian user requests.