In the sixth of our series, we look at military warfare. New munitions technology abounds, but can the US military strike a balance between capability and cost?

Digital signals sleeting through the ether, carrying target images from orbiting satellite to command and control workstation to strike fighter cockpit, seem light years away from the Wright brothers' first flights. But from the early days of military aviation to the latest concepts for network-centric warfare there has been a common theme - holding the high ground. At the beginning it was the high ground of reconnaissance and artillery spotting flights over the blasted quagmires of First Word War battlefields. Today it is high ground of information and intelligence.

Armed forces worldwide are trying to come to terms with the impact of information technology on warfare. Inevitably, the USA has taken the lead in exploiting network-enabled operations, raising the spectre of a tightly networked force that is at once invincible and incapable of co-operating with allies that are not equipped to join the network. It is equivalent to the early days of office IT, when different computers were not compatible with each other. And the solution is similar: the development of industry standards that allow any platform to plug into the network.

Just as advances in commercial technology have made desktop computers more capable, but also easier to use, progress in military technology promises to make it easier for coalition partners to plug into a network and play a valuable role in allied operations. The same hardware and software standards and communication protocols will allow smaller networks to be formed for tasks like homeland defence or peacekeeping operations.

Nowhere is the power and the peril of networking for the military more apparent than in the arena of precision strike, where the flow of time-critical targeting information from sensor to shooter is dependent on datalinks. Standardised communications are essential to coalition operations, but the demands of the military and the capability of the technology do not always line up.

Laser-guided bombs were first used in the Vietnam War, ushering in the era of precision-guided munitions. The concept was simple: illuminate the target with a laser and equip the bomb with a seeker to home in on the reflected energy. The NATO-standard laser-guided bomb is the Raytheon Paveway series, which made its debut in Vietnam but came of age in Operation Desert Storm, when it accounted for over half the precision-guided weapons expended.

The limitations of laser-guided bombs became apparent in Operation Allied Force over Kosovo, where weather and smoke prevented the laser designation of targets, or caused the weapon to lose lock and resulted in collateral damage. The result was development of the Enhanced Paveway, which added a global-positioning/inertial-navigation system (GPS/INS) to the laser-guided bomb. Programmed with its co-ordinates, the weapon will fly to the intended target even if laser designation is denied or lost.

Target to go

Increased use of laser-guided bombs was made possible by the proliferation of targeting pods enabling aircraft to self-designate, or illuminate targets for a group of attacking aircraft. Key was the development of forward-looking infrared (FLIR) sensors that allow targets to be located, identified and designated at night and in reduced visibility. Pods are expensive, and their carriage requires costly aircraft weapon-system upgrades, but precision targeting capability is required for coalition operations so most allied nations buy a handful of systems.

Technology has provided a solution in the form of the GPS/INS-guided bomb. This seekerless, and therefore relatively inexpensive, weapon is programmed with the target's co-ordinates before take-off or before release, and uses satellite-aided inertial navigation to fly itself to the planned impact point. The Boeing Joint Direct Attack Munition (JDAM), which is becoming the NATO-standard GPS-guided bomb, was first used in Kosovo and accounted for half the precision-guided munitions expended during Operation Enduring Freedom over Afghanistan.

Compared with laser-guided bombs, JDAMs can be carried by a wider range of aircraft, including bombers. The weapon has turned the ageing Boeing B-52 into a powerful precision-strike platform in what should otherwise have been the twilight of its career. This gives a hint of how technology is changing military thinking, a process of re-examination that is accelerating as the power of network-enabled operations becomes evident.

While almost any aircraft can be used to carry preprogrammed GPS-guided bombs to the battlefield, a targeting pod still offers advantages (even on a B-52), including the ability to generate co-ordinates for targets of opportunity, to confirm target identity before weapon release, and for post-strike battle damage assessment. But JDAM's "fire and forget" guidance gives the launch aircraft far greater freedom to manoeuvre.

Having established their effectiveness, precision-guided munitions are being developed in several directions, including greater accuracy, longer range, moving targets and different warheads. While JDAM routinely beats its 13m (43ft) accuracy requirement, the military would like to get below 3m to reduce collateral damage. This has been demonstrated under the Damask programme, in which a low-cost imaging-infrared terminal seeker based on automotive technology was flight tested on a JDAM.

The problem is cost, because JDAM's great advantage is its low price. The weapon is simply a tailkit that converts existing "dumb" bombs to precision-guided munitions. With production ramping up to almost 3,000 kits a month, cost has been reduced to around $20,000, while a Paveway laser-guidance kit costs $13,000-15,000. Even a low-cost seeker could add 50% to JDAM's cost, which would make a big difference over the hundreds of thousands of munitions the US and its allies will buy.

The story is similar when it comes to extending JDAM's range, and adapting the weapon to attack moving targets. The military wants the capability, but is concerned about the cost. Experiments have been conducted using pop-out wing kits to extend the range of JDAM from under 30km (16nm) to over 110km, allowing the launch aircraft to stay out of range of air defences, but cost remains the obstacle.

Instead, the US military is pursuing development of a new family of bombs that will extend the capability of GPS-guided munitions. The Small Diameter Bomb (SDB) will be a 115kg (250lb) weapon, half the size of the smallest bomb in NATO-wide use today, but with the destructive capability of a 900kg penetrating bomb. The SDB's small size will allow aircraft to carry more munitions and engage more targets - from eight on a Lockheed Martin/Boeing F/A-22 to around 200 on a Northrop Grumman B-2 - while reducing collateral damage. Two versions are planned: one with GPS/INS guidance for use against fixed targets; and a second with a terminal seeker with automatic target recognition for use against mobile targets. A pop-up wing kit is planned to extend the weapon's range and later versions may have the capability to loiter and autonomously seek out targets.

The current focus of GPS-guided weapon advanced development is on engaging mobile targets. This is part of a wider thrust towards networked targeting technology, enabling forces to attack fixed or moving targets at short notice, at any time, in any weather. The ability to hit a target on the move with a seekerless JDAM has been demonstrated under the US Defense Advanced Research Projects Agency's advanced moving surface target engagement (AMSTE) programme.

The key to networked targeting is to be able to locate and track targets and provide timely and accurate location information first to the launch aircraft then to the weapon in flight. In the AMSTE demonstration, data from multiple ground moving-target indication (GMTI) radars was combined to provide precision targeting. GMTI radars - on airborne ground-surveillance aircraft, unmanned air vehicles and, eventually, even satellites - provide all-weather capability. Combining data from two or more geo-registered radars - called multilateration - allows moving targets to be tracked with fire-control precision.

In the AMSTE demonstration, target updates were datalinked to the launch aircraft, then to the weapon after it was released. The goal was to achieve an accuracy of better than 10m. In tests, the JDAM has scored direct hits on moving trucks. AMSTE prime contractor Northrop Grumman is now proposing producing kits for JDAM - and the Raytheon Joint Stand-Off Weapon, a seekerless glide bomb - for under $12,000, depending on the datalink.

Critical datalink

The choice of datalink is critical to the success of networked targeting technology. A standard datalink, such as the widely used Link 16, is preferred, but may be too bulky and expensive for a weapon like JDAM. A cheaper, more compact UHF datalink would be better, but would incur the cost of retrofitting the GMTI radar platforms. Introducing another unique datalink to the lexicon of tactical communications would also complicate coalition operations.

The Link 16 digital datalink has been around for decades, but is only now entering widespread use. Developed by the USA as the Joint Tactical Information Distribution System, it has been adopted as the NATO-standard Multifunction Information Distribution System and is emerging as one of the key enablers of network-centric warfare.

Unlike earlier systems, which are point-to-point, Link 16 is a multiple-access, jam-resistant digital datalink. There is no controlling node to the network. Each participant is assigned a time slot in which to transmit data. All participants receive all the data, then select from it the information they need. One or more members of the net can act as relays, extending its reach beyond line of sight and to other, similar networks.

The early Link 16 terminals were heavy and bulky and were used only on high-value platforms such as airborne early-warning aircraft, air-defence command centres and ships. The more recent development of low-volume terminals has extended the tactical datalink's use to air-defence and strike fighters. Now tankers and transports are being equipped so that they can act as communications relays and extend the reach of the network.

Conceived in the mid-1970s, Link 16 has a relatively narrow bandwidth by today's commercial communications standards, but designers are finding ways to exploit the datalink to provide an internet-like capability to exchange information - whether it is sending target images direct to a fighter cockpit or mission instructions to an unmanned air vehicle.

The commercial computing industry has adopted on network standards that may not be the best technology can produce, but are the most widely accepted. The technology exists to produce a much better tactical datalink, but is in the military's interest to encourage Link 16's adoption as an alliance standard for network-centric warfare. As long as standards exist, coalition operations will be possible.

Source: Flight International