Barnard Microsystems Limited

Above: the twin engine, twin tail fin, twin flight control unit InView unmanned aircraft.

• Approach
• Design considerations
• Mishap rate
• Causes of failure
• Breakdown of causes of Predator losses
• Shadow 200 passes 100,000 hour mark

• Prototypes to be operated under Harsh Environment Test conditions, to encourage any design weaknesses to manifest themselves at an early stage.
• Detailed and ongoing in-flight tests need to be instituted, accumulating many hours of flight time, to identify failure modes and guide preventative maintenance.
• In a mission, several UA need to be used, to ensure there is always a back up, should any UA experience any problems and need to return to base.

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• Adopt a modular design approach, in which aircraft modules (engine, fuel tank, wing, navigation and flight control modules) and payloads can easily be changed.
• Design the engine unit to contribute minimal stresses to the airframe.
• The engine should be a low vibration engine to reduce stresses on the airframe and payload.
• The UA should have two or more engiines.
• The UA should have multiple, electrically isolated engines, control surfaces and electronics to ensure backup, should any system fail in flight.

The EADS DRAC UAV, developed for the French military, is an example of a twin engined UAV.

complete with a swivel camera

and foldable propellers,driven by electric motors. All photographs from the EADS stand at the Dubai 2007 Air Show.

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UAV Mishap Rates decreasing with time as a result of experience

From uav_roadmap2005.pdf.

From the DoD UAV Roadmap. From www.uavforum.com (link no longer exists) uav_roadmap.pdf.

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from uav_roadmap2005.pdf

Causes of failure averaged over all UAVs, from uav_roadmap2005.pdf

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Data from USA Today, 28th March 2007

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HUNT VALLEY, Maryland, 20 June 2006 - Shadow Tactical Unmanned Aircraft Systems (TUAS), designed and built by AAI Corporation, surpassed 100,000 flight hours, during a June, 2006 combat mission, in support of U.S. forces in Operation Iraqi Freedom (OIF), less than a year after reaching 50,000 hours, in total flight operations.

The hours-of-operation milestone was recorded in the week of June 12 during a sortie flown by a U.S. Army unit, supporting ground operations against terrorism in Iraq.

The 50,000 hour mark was reached on 9 August 2005.

“Shadow systems have proven to be key surveillance and intelligence-gathering assets, in support of U.S. Army and National Guard units in Iraq,” said Steve Reid, AAI’s vice president of unmanned aircraft systems. “For instance, achieving 50,000 flight hours over the last 10 months, means that between seven and eight Shadow aircraft were in the air simultaneously, on average, during every hour, day and night of that entire stretch.”

Since being deployed to Iraq, at the onset of military operations there in early 2003, Shadow systems have flown more than 19,000 sorties and more than 84,000 flight hours, in support of U.S. and allied operations. Total hours include sorties in training and other deployments.

http://www.shephard.co.uk/UVOnline/default.aspx?Action=-187126550& ID=5f0e4974-a548-4b35-ad93-463f517c54e4

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