Monday, January 08, 2007

Small Stealth UAV?

Proposed Small Stealth UAVAn alternative to piloted F-35 stealth aircraft for Australia might be small UAVs. These would cost around $2M each, allowing forty to be purchased for the cost of one F-35 Lightning II Joint Strike Fighter or F/A18F. The UAVs would use engines and weapons from the Australian military inventory and off the self electronics.

Scarab UAV Cross SectionThe US built Ryan Model 324 Scarab/BQM-145A UAV is used by the Egyptian Air Force for reconance. The Scarab is launched from a truck mounted rail with rocket assistance, and recovered by parachute. The Scarab is essentially a reusable unarmed cruse missile. In contrast the EADS Barracuda UAV is a larger conventional wheeled aircraft, allowing it to take off from a runway and with provision for weapons to be carried.

The turbojet engine of the Scarab is similar to that of the Harpoon cruse missile currently in service with the RAAF. The Teledyne J402 turbojet gives the missile a high subsonic speed and good fuel economy. The Joint Air-to-Surface Standoff Missile (JASSM) planned for introduction to the RAAF has a similar engine. The AGM-158A has inertial navigation, GPS, an imaging infrared seeker and data link making it, in effect a disposable armed UAV. However, the cost of JASSM is high, as it can only be used once.

The small turbojet engine design of the Scarab could be combined with the wheels and weapons of the Barracuda to produce a small armed UAV which could operate from a conventional runway. Such an aircraft might be 4 m long, with a 2m wingspan, weigh 1,000 kg, with a speed of 800kph and range of 2,000 km. Typical armament would be one AGM-114 Hellfire air to ground missile or two FIM-92A Stinger air to air missiles (as used on Australian Tiger Helicopters).

The aircraft would be transportable in an NH90 Helicopter or a standard shipping container. To lower the cost, Commercial Off The Shelf (COTS) computers could be used. The aircraft could be equipped with an airborne web server and controlled via a web browser. Automotive components, such as the Controller Area Network (CAN) could be used to further lower cost.

The aircraft would be a limited Unmanned Combat Air Vehicle (UCAV), unlike systemns such as the Boeing Joint Unmanned Combat Air System X-45. The X-45 is much larger with a 10.31m wingspan comparable with a small piloted aircraft. However, at a much lower cost a small UAV would be useful for limited surveillance and attack. It would cause an adversary considerable difficulties, as they would not easily detected.

The small UAV would be useful for attacking small low value targets such as vehicles and small ships, including improvised fighting vehicles ("technicals") and vessels ("boghammars"). Due to its limited armament, the UAV would be less likely to cause concern to Australia's neighbors than full size stealth aircraft and long range cruse missiles.

The Department of Mechanical Engineering at The University of Adelaide, set the building of a miniature radio controlled F-35 VTOL model aircraft as a project in 2004. A conventional larger model would be much less difficult a task. The development of at least an unarmed UAV would be within the capabilities of Australian university researchers.

The US has had difficulties building such Medium Range UAVs, with one program being cancelled in 1993. However, the technology has advanced since then, with carbon fibre being used for UAVs, such as the Australian Aerosonde and COTS computers and low cost commercial avionics being available.

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