Research underway at the Turkish Armed Forces military academy defence sciences institute is warning of a growing imbalance between the cost of a threat UAV and the measures available to western defence forces to destroy it.

Preliminary research results warn that the imbalance has already reached "overkill" proportions in situations where high-cost surface-to-air missiles or manned fighters are being scrambled to engage tactical UAVs.

Likewise, lower-echelon forces are not sufficiently prepared to deal with UAV proliferation. According to researcher leader Kemal Codur, as defence forces and other military organisations, including terrorist groups, field greater numbers of small, mini and micro systems, counter-UAV operations will demand better sensors be available to individual soldiers on the ground.

Aerial mines, adapted from anti-helicopter mines and optimised to respond to hostile UAV signatures, could be a growth area of the future, Codur says. He also suggests that the humble shotgun may have a new role in the front line - as a primary mechanism for countering micro-UAV surveillance by hostile forces.

Detailing preliminary study findings at last month's Unmanned Vehicle Systems International UAV 2007 conference in Paris, Codur said western defence forces have dominated in the development and battlefield proliferation of UAVs. This has resulted in the technology rarely being discussed in terms of its threat potential.

"They do not consider UAVs as an air threat. But as with all technologies, UAV technologies can also be obtained by other countries and even by terrorist groups and this fact has been demonstrated by Hezbollah UAV flights over Israel in 2004 and 2006," he said.

Israel responded to one Hezbollah border incursion during last year's war in Southern Lebanon by using an air force Lockheed Martin F-16 carrying a Rafael Python 5 air-to-air missile to shoot down the low-altitude, low-flying Iranian-built UAV.

Typical air defence threat planning is based on countering combat aircraft that are capable of high degrees of manoeuvre and speed and carry sophisticated electronic warfare self-protection systems. Codur said that in contrast the most common UAVs fly at low speed in pre-planned flight profiles: "They do not change their direction in case of a threat."

The typical UAV airframe has an inherently small signature that is optimised in more advanced types. UAVs can also be produced in their thousands, compared to the limited numbers of aircraft deployed even by a large western air force. "Countries usually have a few hundred combat aircraft and a few hundred missiles and current air defences are organised according to such numbers. But UAVs will be deployed in their thousands and most of the current countermeasures, air defence assets, are overkill for most of those UAV [types]," Codur said. This is particularly the case with mini and micro UAVs he added.

Reliance on detecting those smaller classes using traditional air defence sensors such as radar is unlikely to prove cost effective. Given that units seeking to conduct air defence against mini and micro UAVs are likely to be at lower echelon levels, Codur argues, a variety of alternative sensor types are likely to be required. This would include portable infra-red sensors, already commonplace on the battlefield, optimised to support UAV detection.

Using acoustic sensors to detect UAV engine noise also appears to have some application, however manufacturers are actively seeking to reduce the audible signature of new-generation aircraft, including using electric propulsion systems. Codur also said the limitations of acoustic solutions are compounded by operators using deliberate engine shut-down techniques during critical phases of a surveillance mission.

In contrast, the UAV datalink is a key vulnerability and could be readily located using compact electronic warfare sensors. The datalink could also be a focus for softkill options by using portable jamming equipment.

There are both limits and benefits in electronic warfare solutions, Codur told the conference.

He said that the bulk of such systems tend to be deployed by western forces at higher echelon levels. However, higher echelon electronic warfare capabilities could be valuable in terms of using detection of the datalink to geolocate the threat UAV ground station and support its engagement using heavy weapons fire.

Engagement of tactical class threat air vehicles could be conducted reasonably cost-effectively using standard man portable air defence missiles, Codur said, as the value of such weapons is comparable to that of the UAV. Air defence artillery systems will have similar application.

There is also a role for attack helicopters in engaging larger UAVs because they have "suitable sensors, suitable weapons and similar flight characteristics", he added.

The most basic level of defence would be provided by the individual soldier himself using his personal weapon. In that context the shotgun would be a valuable addition, given its area effect. "They have spreading munitions which create a metal wall and increase the chance of a hit," Codur said.

Development of specific air defence architectures optimised to counter UAVs will, however, result in more intelligent UAV capabilities. Codur warned that while electronic warfare self protection systems are generally too large and too heavy to be carried by most UAV types, continued technological development will make this increasingly possible in the future.

He also suggested that smaller classes of UAV could use acoustic sensors to detect and localise ground-based gunfire, providing a means of intelligent threat avoidance. "If you cannot hit that type of UAV with the first shot they may have a chance to get away," he warned.

Source: Flight International