Infantry troops will test backpack-size drones.

The Army 25th Infantry Division will be testing later, this year five unmanned air vehicle systems--small UAVs called micro air vehicles." Each MAV system contains a ground control station and two air vehicles in a backpack weighing 40 pounds or less.

The Defense Advanced Research Projects Agency oversees the MAY program, and predicts the vehicle could be operational by 2010. DARPA officials foresee that the ducted-fan MAV may complement conventional fixed-wing UAVs in the future.

Unlike fixed-wing UAVs with greater range and endurance, the vertical takeoff and landing MAV can hover and stare at targets. It is being designed to operate in urban settings, and to be carried by dismounted soldiers. Prime contractor Honeywell Defense and Space Electronic Systems is leading a team to refine the compact, but inherently unstable, ducted-fan configuration. The system passed a critical design review in June.

The 11.5 inch diameter, 12.5 pound MAV should fly for the first time at the company's Albuquerque facility in late July. At 5,500 feet above sea level, Albuquerque provides a high density-altitude to tax the payload and endurance. "This is one of the issues with rotor systems.... They don't like to fly high," says Brad Tousley, program manager at DARPA Tactical Technology office.

Honeywell will deliver 10 gasoline-powered prototypes by the end of 2004 and 50 diesel-fueled vehicles by the end of 2005, Army evaluations at Fort Benning, Ga., and Scofield Barracks, Hawaii, are expected to precede a deployment to Iraq.

The UAV can carry cameras, biological and chemical detectors, mine detectors, platoon-level communications relays and a datalink. The demonstrators for the 25th ID will be equipped with off-the-shelf daylight or infrared cameras and a commercial datalink.

The diesel-powered ducted fan MAV is expected to fly at speeds up to 40 mph and hover for 60 minutes at sea level, 40 minutes at 5,500 feet, or 20 minutes at 10,000 feet.

DARPA launched the Micro Air Vehicle program in late 2001, in an effort to develop affordable backpack UAVs.

The 25th ID plans to give instructor and operators 16 hours of training in preparation for MAV experiments.

The ducted-fan MAV wraps a fixed-pitch fan in an aerodynamic shroud with moving exhaust flaps that divert the fan thrust for vertical takeoff, inclined cruise, surveillance hover and vertical landing. "It never flies horizontally," says Honeywell engineer Mark Simmons. "It became obvious the hard part was stabilizing the platform."

After a six-way competition, Honeywell chose AAI Corporation to make the vehicles.

The gasoline-engine UAVs present the biggest challenge in the program. "We don't want to put volatile fuel on the back of a dismounted soldier," says Tousley. Although diesel fuel is a more desirable option, "The hardest piece is that there does not exist a large base of 3 horsepower class diesel engines. The commercial market never had a need to drive it. ... We have to do it."

An industry competition sought bids for a 3-4 horsepower custom diesel engine. "You just can't buy little diesel engines this size," says Simmons. Honeywell plans to select an engine supplier in about a year.