The practical problems.

Combat drones may be coming, but serious doubts persist over such matters as uninhabited air vehicle autonomy, the feasibility of carrier-based operations, attrition rates, life-cycle costs, communications bandwidth, flexibility in reactive defence suppression, combined operations with manned aircraft and the practicality of operating swarms of drones.

**********

When future historians look back at recent CIA operations with armed drones in Afghanistan and Yemen, they may well liken them to events of 1910 and 1911, when a rifle was fired from an aircraft for the first time, and the first bomb was dropped. If the combat drone is really to play a major role in aerial warfare across a broad range of scenarios, it will have to be an affordable, stealthy vehicle with weapons designed specifically for it, and must include sufficient processing power and artificial intelligence for a high degree of autonomy in locating and identifying targets. It will also need high-bandwidth secure communications links that provide it with data from airborne and space assets for total situational awareness as well as some degree of human control to minimise collateral damage and casualties, and to deal with failure modes beyond the capacity of the drone itself.

A recent report by the US General Accounting Office (GAO-03-598: <<Matching Resources to Requirements is the Key to the UCAV Program's Success>>) identified five high-risk development aspects:

* survivable air vehicle integration

* advanced targeting and engagement process

* low observable maintainability

* adaptive, autonomous operations

* affordable large-scale software.

The list of medium-risk challenges further included:

* air vehicle affordability

* weapons suspension and release

* secure, robust communications

* turnaround time.

One of the fundamental difficulties in planning for combat drones is to develop a realistic concept of operations (Conops). Over the past 40 years firm operational requirements have been developed in the United Sates for five basic categories of drones, but these have always addressed different forms of reconnaissance or surveillance. In the field of combat drones there is no legacy role, no real foundation for Conops and operational requirements. All that exists is a wish list, and a general acceptance that the necessary technologies are advancing toward the point at which combat drones may well prove the best approach to specific tasks.

How soon such air vehicles may realistically be available is perhaps best illustrated by the Pentagon's <<UAV Roadmap 2002>>, which pointed to combat drones being introduced in the ordnance delivery Sead role (alongside the EA-6B) between 2005 and 2010. Their introduction into strike role (AV-8B and F-117A) is expected to follow from the 2010 to 2015 timeframe, in the integrated strike/Sead role (EA-6B and F-16) in 2015 to 2020, the counter-air mission (F-14, F-15, F-16) sometime in 2020 to 2025, and the integrated strike/Sead/ counter-air mission (F/A-18, F/A-22) between 2025 and 2030.

It currently appears that there will be some slippage in the first (Sead) category under J-Ucas (Joint Unmanned Combat Air Systems), which is expected to provide the US Air Force and US Navy with several programme options only in a FY2007 to 2009 timeframe. For the US Army, subject to satisfactory review at the end of FY2009, the Ucar (Unmanned Combat Armed Rotorcraft) is expected to enter service in 2015.

Conops

It has become standard practice for the US services to use battle labs to develop Conops for emerging systems that have the potential to transform warfare. The idea of battle labs originated with the US Army in 1992, when six were opened. For example, the Advanced Aviation Technology Directorate is converting an AH-1F into an optionally-piloted Unmanned Combat Airborne Demonstrator (Ucad). Likewise, the Air Maneuver Battle Lab is developing combined UAV/helicopter tactics, using a fleet of 30 BAI Aerosystems BQM-147 Exdrones (out of more than 500 built), while the Dismounted Maneuver Battle Lab is evaluating micro air vehicles in urban warfare scenarios.

The other US services followed the Army's lead, the US Air Force establishing its UAV Battle lab in 1997, while the Marine Corps Warfighting Lab was created in 1995, and the Naval Strike and Air Warfare Center has been working since 1998 on integrating UAVs with carrier air wing operations.

It seems likely that Conops for combat drones will be established by such battle labs only when they have full-scale, properly-equipped vehicles to evaluate. In the meantime, limited trials are proceeding with much smaller drones. A little-known project in this category is the tube-launched 363 kg SAIC Lewk (Loitering Electronic Warfare Killer), which this year is scheduled to demonstrate limited radar jamming and lethal/non-lethal munitions delivery for the Sead mission.

One special concern is the question of whether combat drones can be integrated into the established US Navy carrier operating cycle, or whether they will require their own ships, which could well be the case if vertical attitude take-off and landing is adopted. In addition, it is difficult to predict turnaround times in carrier operations, since there is probably little experience of maintaining low observable materials in a saltwater environment. For the US Air Force, one of the key questions must surely be whether or not non-attritable combat drones can realistically be tasked with the electronic attack mission, given the availability of home-on-jam air defence missiles.

Autonomy

There appears to be general agreement that combat drones must be given a high degree of autonomy, if only to reduce communication bandwidth demands to an acceptable level. On the other hand Darpa, in its "J-Ucas Overview" states that these new drones will "enable a new paradigm in warfighting while maintaining the judgment and moral imperative of the human operator".

This kind of talk may play well in Peoria, but it will be recalled that human US Army Patriot operators mistook a Tornado and a Hornet for ballistic missiles during the invasion of Iraq. It was a human US Navy Standard missile operator aboard the USS Vincennes, who in 1988 mistook an Iran Air A300B2K for an Iranian Air Force F-14 over the Persian Gulf. It was a human US Air Force A-10 operator who mistook a Warrior armoured vehicle for a Russian tank during Desert Storm. It is arguable that the best long-term approach is to develop a thoroughly dependable IFF system, and restrict human intervention to cases in which the drone is clearly in the wrong area.

As the present-day leader in most aspects of drone development, America has introduced a system for measuring levels of drone autonomy. The Boeing Condor of 1988 was capable of autonomous pre-programmed flight, and was capable of redundancy management of subsystems and the use of alternate runways. The Northrop Grumman RQ-4 Global Hawk (with autonomy rated at Level Two to Three), benefits from increased computational power. It is able to deal with a much wider range of contingencies, using pre-programmed corrective actions for such problems as loss of datalinks, navigation components or flight computers. The Frontier Systems A160 is intended to bring a similar degree of autonomy to rotary-wing airframes.

The US Air Force/US Navy J-Ucav will further advance autonomy, with inter-vehicle datalinks to share information. It will make possible co-operative actions, with the drones flying either unescorted or as the forward element of a mixed manned/unmanned force. The J-Ucav will demonstrate at least Level Six autonomy.

The US Army's Ucar will represent another forward step in collaborative behaviour, with Level Eight to Nine autonomy. Beyond sharing information, the system will make possible collaborative search, target identification and engagement and damage assessment. The Ucar will also be able to distil general mission objectives into specific mission plans.

Technology

The principal advances that make combat drones feasible relate to sensors, processors and communications bandwidth. In the field of sensors, substantial progress is being made in radars, ladars and lidars (light detection and ranging), with special reference to foliage penetration and sub-surface imaging. Advances are also taking place in effluent and aerosol detection and identification, onboard image enhancement and lightweight mass storage arrays to compete with wet film in terms of pixels per kilo. US sensor goals include the demonstration by FY2005 of HDTV (high definition television) on a drone for real-time precision targeting and sensors that are compatible with a tactical UAV and will detect (at least) a single tank concealed under trees, and (ideally) a heavy machine gun.

Advances in processors are crucial not only for autonomous operation, but also for onboard sensor data processing and more responsive flight control systems. Ironically, the future for combat drones depends on the commercial sector continuing to produce increasingly capable processors. In 1965, Gordon Moore of Intel produced his well-known Law stating that the number of transistors on a processor (and hence microprocessor speeds) will double every twelve to 18 months. Based on Moore's Law, which has so far proved remarkably accurate, Terahertz (1000 GHz) processors may be expected to be commercially available between 2015 and 2020. However, this will represent a limit for silicon chips, and a switch to gallium arsenide, offering ten times the speed, may then be expected.

Until such time as drones have sufficient onboard power to process all their information and relay only the results to the ground, datalink bandwidth will remain a problem. The current state-of-the-art in RF datalinks is represented by the Global Hawk, which can currently relay 274 Mbps and is expected to reach 548 Mbps by 2015. With better modulation methods, it is predicted that current bandwidths will allow rates up to ten Gbps. Optical datalinks or lasercom offer the prospect of data rates up to five orders of magnitude greater than the best foreseeable RF systems, but will not be applicable to low level combat drones, which need all-weather capability.

Weapons

If combat drones are to be survivable, they must have stealthy designs with internal weapon bays, which in turn demand small but effective (i.e., precisely delivered) weapons. The 130 kg Boeing GBU-39/B SDB (Small Diameter Bomb) is the principal example to date, being designed to deal with a target set that includes command, control and communications bunkers, air defence assets, fuel dumps, airfield targets and artillery. The General Dynamics APKWS (Advanced Precision Kill Weapon System), using a Hydra 70 rocket with a BAE Systems laser homing kit, is scheduled to be employed on the US Army's Ucar project. For fixed-wing combat drones (flying higher than rotary), stealth design considerations favour a dorsal weapons bay, although this would most certainly require the development of a new generation of armament carriage and ejection systems.

Attrition

One of the major challenges arising in developing cost-effective combat drones is the need to achieve an order-of-magnitude improvement in UAV attrition rates. The seriousness of the problem is indicated by US loss rates per 100,000 flight hours, with 334 air vehicles for the Pioneer, 55 for the Hunter, and 31 units for the RQ-1B Predator. For comparison, the Stovl AV-8B rate of around 10.5 is considered high for a manned aircraft (for good reason). Good practice is illustrated by the 3.5 of the F-16 and 3.2 of the F/A-18. Part of the solution is to give drones a much higher level of systems redundancy. The Pentagon has set targets for a major mishap rate of less than 20 by FY2009 and less than 15 by FY2015.