Maritime drones--back to the future? One of the many panaceas for modern naval operations is the Unmanned Aerial Vehicle (UAV), which offers the ship commander his own means of aerial reconnaissance over both land and sea. The UAV--or drone--is regarded as a major tool in littoral naval operations, but what is emerging is a concept that was viewed as absolete some 60 years ago.

The advantage of the UAV is that it provides a relatively low cost, expendable platform for reconnaissance, surveillance and observation. Navies first acquired manned aircraft for this role during the First World War, indeed back in 1918 almost every British battleship and cruiser could carry reconnaissance aircraft able to fly off platforms lashed to gun turrets. In the next two decades these were replaced by steam-driven catapults but by the end of the Second World War carriers were the flag-bearers of naval aviation and other surface combatants quickly ceased to have organic airborne reconnaissance.

Drones have recently been touted as the way forward certainly for aerial reconnaissance but it appears that only the United States has a coherent programme for developing and introducing them into service. Remotely operated target aircraft were used from the 1930s onwards but UAVs did not appear in ships until the 1950s when a rotary-wing aircraft, the QH-50 Drone Anti-Submarine Helicopter (Dash) was developed by the US Navy. Flown from a dedicated platform, it was not popular because of its electro-optic sensor which assisted flying the aircraft, some of which landed upside down, and was withdrawn by the Pentagon in the late 1960s--although the Japanese Maritime Self-Defence Force had no problems with its systems (incidentally, the Dash is a reminder that those aircraft were originally called drones, the unmanned aerial vehicle and its UAV acronym, one more!-are purely a product of the American administration).

Improvements in communications and guidance have led to a resurgence of UAVs from the late 1980s but there remain fundamental problems of launching and recovery. The US Navy identified a need for drones after operations in Grenada, Lebanon and Libya for both reconnaissance and bomb damage assessment, and in July 1985 a competition for off-the-shelf systems began, this was won by the IAI Pioneer (see title picture from AAI) which deployed with the battleship USS Iowa in December 1986.

The following year the US Marine Corps bought the system for use off Tarawa class amphibious assault ships, as the US Navy had extended the use of drones to the remaining three battleships as well as integrating it with the Austin class amphibious transport docks. Equipped with an IAI Tamam Moked TV system the RQ-2A pioneer successfully supported the battleships during Operation Desert Storm, and on one famous occasion their mere presence led to the surrender of an Iraqi position.

With the decommissioning of the battleships they now serve only in six of the Austin class (two more are scheduled to receive the system) while the RQ-2B, with a Versatron Smallball or Wescam 12DS infrared camera and colour TV system, serves with the Marines from Tarawa class ships. They are launched from a flight deck like a conventional fixed wing aircraft, but with a Jato (Jet-Assisted Take-Off) booster, and recovered by flying into a net with an energy absorbing system. Such activities clearly interfere with helicopter operations and it is interesting to note that by mid-September 2003 the US Navy's Pioneer squadron, VC-6 with four systems, had flown less than 92 hours compared with nearly 2600 for the US Marine Corps.

Whirly Types

Fixed wing systems tend to be easier to operate and have higher endurance than rotary wing types, but the problems of launch and recovery remain. The South Korean Navy uses a system similar to the US Navy for its AAI Shadow 400 system, while operation like conventional fixed-wing aircraft is used in the Aeronautics Aerolight, evaluated by the US Navy, and the Inta/Ceselsa/Eads Dornier Siva (Sistema Integrado de Vigilancia) being developed for all three Spanish services. In 1996 the US Navy conducted an experiment in which it simulated a launch from a missile container in a submarine torpedo tube and an aircraft already in the air was then guided by the submarine to the target and recovered by parachute. This concept has been proposed for the Northrop Grumman Sea Ferret but does not appear to have been developed further.

One solution to the launching problem might be to reintroduce catapults for fixed-wing drones as they were used for seaplanes between the wars. With greater generating capability in modern surface combatants electric catapults are feasible and might be used in association with automatic recovery systems. Certainly unmanned aircraft might prove a useful tool for ships just like manned helicopters.

Indeed, for shipborne use a simpler solution might be a rotary wing drone that would share the flight deck/hanger facilities, although rotor vibration can have an adverse effect upon electro-optical payloads. Conventional airframe solutions include the lightweight (68 kg) Austrian Schiebel Camcopter, of which two systems have been delivered to Egypt, and the Eads Dornier Seamos (See-Aufklairungsmittel und Ortungssystem), which was developed for German Navy corvettes and frigates and was originally based on a modified Dash dynamic system. An accident to the demonstrator in 1999 led to the abandonment of the programme although the manufacturers continue to market the product.

Less conventional approaches include the Orion 706 Seabat, a tail-sitting aircraft designed as a private venture in consultation with the US Navy but possibly now moribund. Bombardier (formerly Canadair) developed an airframe with the rotors in the middle giving the impression of a flying peanut. The CL-227 Sentinel was tested in US Navy frigates in the early to mid 1990s with the Sierra Nevada UAV Common Automatic Recovery System (Ucars) which uses a radar tracker and aircraft transponder to land aircraft with an accuracy of up to 18 cm of the centre point. The more powerful CL-327 Guardian was tested by the US Navy but withdrew from the US Navy's Vertical Tactical UAV (VTUAV) contest due to concern about its ability to meet requirements of speed, payload and endurance.

The Vertical Tactical UAV programme began in January 1999 with a Request for Proposals some seven months later. This led to the Northrop Grumman RQ-8A Fire Scout, which is an unmanned and modified Schweizer 333 light helicopter giving a take-off weight of 1.15 tonnes to make it the heaviest rotary-wing naval drone in the skies. The aircraft is launched like a conventional helicopter and recovered with a Ucars. Programme development has been protracted and subject to doubts but it has recently passed exhaustive tests including the first fully autonomous flight and it is attracting interest from Australia, Germany and Japan.

Northrop Grumman is planning a more powerful version, with four rather than three rotor blades as the MQ-8B Sea Scout, with 14 per cent greater take-off power, 45.5 kg of extra fuel and a 250 kg increase in gross weight. The current electro-optics (TV, thermal camera, laser designator/rangefinder) would be replaced by a synthetic aperture radar and it could carry weapons such as air-to-air missiles. The US Navy was hoping to secure FY04 funding for development of this version.

Naval but Dry Feet

Alternatives to shipborne vehicles are land-based aircraft in a role similar to that of the maritime patrol aircraft. The US Navy has the Broad Area Maritime Surveillance (Bams) programme with Phase II responses in October and a contract award anticipated in May 2004. The concept is for a land-based drone capable of providing around-the-clock reconnaissance and surveillance coverage and strike support over a range of at least 2780 km for 24 to 36 hours. It would have a 360 [degrees] radar with a detection range of 200 km and a signals intelligence payload and later a hyper-spectral imaging sensor or a communications relay system.

The initial operational capability is scheduled for 2007 or 2008 and potential contenders include Northrop Grumman's RQ-4A Global Hawk and the General Atomics' RQ-1B Predator. The US Navy has stated the Bams will act as an information collection hub operating either independently or in direct collaboration with other manned, unmanned and space-based platforms with worldwide coverage from just five bases.

A number of other new long-endurance land-based UAVs with similar sensor packages could perform like roles on a regional basis, including the Eads Fregate, the Silver Arrow Hermes 450 and 1500 as well as IAI's Heron and Searcher. The advantage of this concept is that it would offer lower cost and higher endurance alternatives to maritime patrol aircraft for covering wider areas, but they will not be cheap.

Not only are long-endurance UAVs on the horizon to support naval operations but also the prospect of Unmanned Combat Air Vehicles (Ucav). The purpose of these combat drones was originally the Suppression of Enemy Air Defences (Sead) and attacks upon high risk, high value targets. In 2000, Northrop Grumman and the US Navy began a feasibility study of the Naval Ucav (Ucav-N) beginning with the X-47A Pegasus to demonstrate that a simple, low-cost and very stealth-compatible shape can approach and land with the speed and accuracy required by carrier operations. One feature the Ucav-N will need is compatibility with the Shipboard Relative Global Positioning System, which can locate a landing aircraft relative to the carrier deck within 20 cm in three dimensions. It is hoped that the X-47A programme will facilitate development of either Boeing's X-46 or the X-47B as the Ucav-N, which the US Navy hopes will enter production from the end of the decade.

However, the Ucav-N project has been absorbed with a similar US Air Force programme in 2003, as the US Defense Department established a joint programme office and a Joint service combat UAV (J-Ucav), which would include a carrier-based version. The naval element will be led by Boeing and/or Northrop Grumman.

The US Navy is unlikely to have more than six combat drones per carrier and with relatively few aircraft likely to be purchased they will need to be multi-mission, indeed it is possible that an overland reconnaissance element will be added, and this rather than strike will become the primary role. Not only will the US Navy have problems with controlling the aircraft in the sky but there is also major deliberation about movement around the crowded kaleidoscope of the flight deck and how this will be achieved safely. Here radio control or temporary manned control are options.

Another problem will be the storage of the aircraft. Will they be stored like their manned counterparts and absorb space that could be made available for manned aircraft or crated and assembled on a per-mission basis? But in the crated scenario there will be problems with features such as the hydraulic system that will leak over time and possibly render the apartus non-operational even after assembly. For naval drones and combat drones another problem will be the question of who is to control the aircraft. Should highly trained pilots be assigned the task or technical specialists equivalent to radar and sonar operators?

Unmanned aircraft will certainly play a part in littoral operations from the end of the decade but to what degree is uncertain. The fact is that achieving performance capabilities equivalent to manned aircraft requires expensive electronic guidance and control systems together with sensor systems which, even high quality electro-optic ones, will also absorb funds which are becoming scarcer.