30 mai 2013
RQ-11B Raven small Unmanned Aircraft System photo US Army
.May 30, 2013: Strategy Page
With combat operations winding down in Afghanistan, the U.S. Army is cutting back on purchases of its popular Raven micro-UAV. In the last decade the U.S. has bought most of the 19,000 Ravens produced. But now those purchases are fading to zero. Last year the army bought 1,134, this year it was 234 and next year it is zero. The reason why the army has bought so many Ravens is because this tiny (two kg/3.3 pound) rapidly wears out in combat. The Raven is made of Kevlar, the same material used in helmets and protective vests, but there are many ways for one to be lost in combat. On paper a Raven can survive about 200 landings before it can no longer be used. That’s in peacetime operations. In a combat zone few Ravens make it past fifty or so landings. While some Ravens have been shot down, the most common cause of loss is a problem with the communications link (as the aircraft flies out of range or behind something that interrupts the signal) or a software/hardware failure on the aircraft. Combat losses have been high, as nearly 20,000 have been built and most of those have been lost on the battlefield.
With much less combat expected in the next few years, the army is cutting orders for new Ravens and, in effect, living off existing stocks (over 5,000 Ravens) and resuming purchases only if a lot of troops are sent into combat. Raven, in effect, is being treated like ammunition, with much needed in peacetime than in wartime.
Despite the high loss rate the Raven is popular with combat and non-combat troops alike. In part this is because the army has developed better training methods, which enables operators to get more out of Raven more quickly. Combat troops use it for finding and tracking the enemy, while non-combat troops use it for security (guarding bases or convoys). In both cases troops have come to use the Raven for more than just getting a look over the hill or around the corner. The distinctive noise of a Raven overhead is very unpopular with the enemy below and is often used to scare the enemy away or make him move to where he can be more easily spotted.
The current model, the Raven B (RQ-11B), was introduced six years ago, a year after the original Raven entered service in large numbers. This UAV is inexpensive ($35,000 each). The Raven is battery powered (and largely silent unless flown close to the ground). It carries a color day vidcam or a two color infrared night camera. It can also carry a laser designator and a new gimbaled camera is being bought. The cameras broadcast real time video back to the operator, who controls the Raven via a handheld controller, which uses a hood to shield the display from direct sunlight (thus allowing the operator to clearly see what is on the ground). The Raven can go as fast as 95 kilometers an hour but usually cruises at between 40 and 50 kilometers an hour. It can go as far as 15 kilometers from its controller and usually flies a pre-programmed route, using GPS for navigation.
From the very beginning the Raven changed the way troops fight. With the bird's eye view of the battlefield, commanders can move their troops more quickly, confident that they won't be ambushed and often with certain knowledge of where the unseen enemy is. The big advantage with Raven is that it’s simple, reliable, and it just works. The UAV can be quickly taken apart and put into a backpack. It takes off by having the operator start the motor and then throwing it. This can be done from a moving vehicle and the Raven is a popular recon tool for convoys. It lands by coming in low and then turning the motor off. Special Forces troops like to use it at night because the enemy can’t see it and often can’t hear it either.
Puma unmanned aerial vehicle-launch
Last year the U.S. Army began using the larger (5.9 kg) Puma AE UAVs. Adopting Puma is part of an army effort to find micro-UAVs that are more effective than current models and just as easy to use. The Puma, a 5.9 kg (13 pound) UAV with a 2.6 meter (8.5 feet) wingspan and a range of 15 kilometers from the operator, has proved to be the next big (or micro) thing the army was looking for. Combat commanders quickly realized how useful Puma is and wanted more, as quickly as possible. This is not surprising as SOCOM (Special Operations Command) has been using Puma since 2008.
The army wants to equip each infantry company with a Puma system. That would mean 18 Puma AE UAVs per brigade and nearly 400 for the entire army. These larger UAVs have been most useful in route clearance (scouting ahead to spot ambushes, roadside bombs, landslides, washouts, or whatever). The larger Puma is particularly useful in Afghanistan, which is windier than Iraq and thus more difficult for the tiny Raven to operate.
Top speed for Puma is 87 kilometers an hour and cruising speed is 37-50 kilometers an hour. Max altitude is 3,800 meters (12,500 feet). Puma has a better vidcam (providing tilt, pan, and zoom) than the smaller Raven and that provides steadier and more detailed pictures. Because it is larger than Raven, and three times as heavy, Puma is much steadier in bad weather. Both Puma and Raven are battery powered.
Puma has been around for a decade but never got purchased in large quantities by anyone. The latest model uses a lot of proven tech from the Raven (both UAVs are made by the same company). Like the Raven, Puma is hand launched and can be quickly snapped together or apart. Another version, using a fuel cell, has been tested and was able to stay in the air for nine hours at a time. There is also a naval version that floats and is built to withstand exposure to salt water.
Each combat brigade is now supposed to have 35 mini-UAV systems (each with three UAVs, most of them Raven but at least ten of these systems are to be Pumas). That means that each combat brigade now has its own air force of over a hundred reconnaissance aircraft.
The army currently has nearly 7,000 UAVs. Over 6,000 are micro-UAVs like the Raven and Puma. These tiny (under six kg/13.2 pound) reconnaissance aircraft have become very popular with the troops, anyone of which can become an operator after a few hours of training. These tiny UAVs are a radical new military aircraft technology that took air recon to a new level. That level is low, a few hundred meters off the ground. The army has nearly 1,798 Raven and 325 Puma UAV systems in use by ground troops. A complete system (controller, spare parts, and three UAVs) costs $250,000 for the Raven and over $400,000 for Puma. These tiny aircraft have changed how the troops fight and greatly reduced army dependence on the air force for air reconnaissance. The lightweight, hand launched Raven UAV can only stay airborne about an hour per sortie, but troops have found that this is enough time to do all sorts of useful work, even when there's no fighting going on. This is most of the time. The heavier Puma can stay up for 120 minutes.