Mighty Minis Find Foes

June 2006
By Clarence A. Robinson Jr.

The Defense Advanced Research Projects Agency (DARPA) unmanned micro air vehicle (MAV) performs a hover-and-stare maneuver at a contractor test facility in New Mexico. Successful in-flight testing moved the program toward advanced concept technology demonstration tactical operations with soldiers in Hawaii.
Vertical flight vehicles enable operations in tight spaces to locate hidden snipers, traps.

Diminutive but potent, a versatile unmanned micro air vehicle leaps tall buildings to look for rooftop shooters or hovers and stares through windows to search within for hidden enemies. New applications continually tumble forth for a 14-pound ducted fan vertical takeoff and landing aircraft. This nascent platform rapidly is being recognized for its important platoon-level infantry and cavalry reconnaissance capabilities.

Within the next few months, if all goes as planned, this micro air vehicle (MAV) could be en route to Afghanistan and Iraq for U.S. Army convoy and other reconnaissance applications. Uses include scout missions, possible detection of treacherous improvised explosive devices (IEDs) and urban combat. MAV provides a 10-kilometer (6-mile) communications range using common military unmanned aerial vehicle (UAV) frequencies.

Developed by the Defense Advanced Research Projects Agency (DARPA), Arlington, Virginia, MAV’s sensors can detect and recognize man-size targets at 250 meters during daylight and at 125 meters at night. Forward- and downward-looking electro-optic and infrared sensor pods also can see through fog, dust and sand to locate targets accurately, according to Dr. Brad Tousley. He is the senior scientist and program manager in DARPA’s tactical technology office. The air vehicle’s sensors can transmit imagery in real time, store 10 minutes of imagery onboard or store 60 minutes of video with the groundstation. The sensors also are modular and interchangeable.

This vertical takeoff and landing (VTOL) UAV provides endurance of 40 minutes at altitudes of 5,500 feet and great flexibility for small combat units. Generally, however, MAV operates at altitudes between 100 feet and 500 feet above the ground. Moreover, MAV can climb at a rate of 25 feet per second, transition to horizontal flight and fly to an objective at a 50-knot airspeed, Tousley points out. MAV also can take off and land in 15-knot winds and can fly in 20-knot winds and rain with a service ceiling of 10,500 feet.

Collectively, MAVs have made several hundred flights during the past two years and are scheduled to go to operational users in the 25th Infantry Division for more extensive assessment this October. Earlier advanced concept technology demonstration (ACTD) experiments with the same Hawaii-based division unfolded in an urban combat training environment late last year. MAV, with limited upgrades and improvements, is scheduled to return to Hawaii for continued use by division soldiers.

Successful applications on a range in Hawaii could lead to an urgent requirements statement from the division for MAV’s combat use in operations Enduring Freedom and Iraqi Freedom, Tousley says. A graduate of the U.S. Military Academy at West Point, New York, he recently was selected as the U.S. Defense Department’s ACTD manager of the year. The vehicles would go to Iraq or Afghanistan for use with units already deployed there. It takes little specialized training to instruct soldiers how to handle the UAV with simple intuitive operations. MAV’s deployment and stowing operations are accomplished within five minutes.

As the MAV program manager, Tousley is demonstrating the technologies for a manpackable, vertical-lift UAV system suitable for dismounted soldier, U.S. Marine Corps and special forces missions. Earning a master’s of science degree and a doctorate in electrical engineering from the University of Rochester, he also brings 20 years of Army armored cavalry unit service to the ACTD effort. The longer soldiers use the vehicle, the more resourceful ideas and ingenious concepts emerge for UAV applications, especially in urban terrain, he emphasizes.

The possibility also exists to arm the UAV with small missiles or to equip it with a variety of sensors such as hyperspectral devices to locate IEDs and other concealed targets. In a parallel IED detection effort, a Defense Department task force is working with prime contractor Honeywell Aerospace to conduct experiments in China Lake, California.

In addition to a hover-and-stare mode, the versatile UAV also operates using a perch-and-stare technique functioning as an unattended ground sensor system, Tousley reveals. This application greatly conserves fuel while the platform’s inherent flexibility allows it to relocate to other positions or to take off to track targets as they move.

It is the lift-augmented ducted fan propulsion technology that provides MAV’s unique capability. Powered by a small gasoline engine and a fan that acts as a propeller, and enclosed by a duct, MAV draws air through the duct and ejects it out the bottom to generate sufficient thrust to function as a helicopter.

Tousley also relates that DARPA is competitively developing a larger, 150-pound version VTOL UAV for use by company-size combat units. This developmental effort is known as the Organic Air Vehicle (OAV) II program. While MAV developmental funding is approximately $50 million, OAV II is “times two,” or about $100 million, he explains. OAV II flights are scheduled to begin in mid-2007 at the Army’s White Sands Missile Range, New Mexico, and to run for about two years.

DARPA conducted a series of studies circa 1995 concerning MAV programs that included industry involvement to examine both fixed-wing and other flight concepts. That effort included augmented ducted fan technology, Tousley continues. By 2000, ducted fan technology split into two paths—one to develop a small ACTD vehicle and the other to continue exploring size and performance issues to meet various military requirements. In 2003, the ACTD program was restructured and Honeywell Aerospace, Albuquerque, New Mexico, won a contract to develop the smaller UAV. Soon after, the company began conducting MAV flight tests at the Laguna Indian Reservation 40 miles to the west.

Last year DARPA also recompeted the larger OAV II program, focusing on specific requirements for the Army’s Future Combat Systems as a company-level platform, Tousley discloses. This program calls for developing the larger ducted fan UAV for diverse missions in complex environments—reconnaissance and surveillance missions, path finding for both robotic and manned vehicles and targeting for non-line-of-sight operations. Honeywell also is developing the OAV II platform, competing against Aurora Flight Sciences, Manassas, Virginia.

Aurora’s UAV offering is called GoldenEye-OAV. It takes off vertically and transitions to horizontal wing-borne flight. The aircraft accomplishes this by using torsionally disconnected, or free-floating, wings. The wings turn into the wind during hover flight to reduce the aircraft’s vulnerability to wind gusts. As the aircraft accelerates and transitions to high-speed forward flight, the wings begin to produce lift and support the UAV. This approach burns less fuel while realizing faster speeds and greater endurance.

Tousley compares the size of the two UAVs, noting that MAV weighs 14 pounds wet, or fully fueled, is 21 inches wide and has a 13-inch duct diameter. The OAV II’s duct diameter is 33 inches. Whereas the MAV carries strap-down forward- and downward-looking cameras, the OAV II is being equipped with a fully gimbaled day-night sensor system and a laser target designator. MAV design requirements mandate that the aircraft be small enough to be carried in a backpack. This 40-pound load is split between two soldiers. Vehicles, however, are necessary to move an OAV II.

The OAV II is designed to take off vertically, transition to horizontal flight, fly out 15 kilometers, hover on station for two hours and fly back. Trade-offs between hover time and range can increase the UAV’s distance to 80 kilometers, Tousley allows. The OAV II also is being equipped with an infrared ball turret and will operate with an autonomous laser detection and ranging collision avoidance system to steer clear of obstacles such as telephone lines, tree limbs and buildings. The smaller MAV does not have this capability, relying instead on the operator. The Army’s Night Vision Laboratory, Fort Belvoir, Virginia, is managing OAV II payload development.

The DARPA MAV hovers to stare with its sensors trained on a partially open second-floor window during urban combat training. U.S. Army soldiers can learn quickly to operate the UAV effectively, usually within 24 hours.
DARPA worked with the Army Infantry School at Fort Benning, Georgia; Army aviation officials; the UAV systems program manager; and the 25th Infantry Division to determine and prioritize MAV mission requirements, Tousley continues. “What emerged were the day-night camera system and that MAV had to be capable of flying with a platoon at patrol altitudes. In locations such as Afghanistan, this means operating at altitudes up to 10,000 feet. When you put the requirements together, those requirements size the vehicle at a 13-inch diameter duct for sufficient lift,” he adds.

A small 89-octane gasoline engine is being used on MAV; however, a diesel fuel engine also is in development. The engine is mounted on top of the platform, and the avionics and sensor pods are to either side. A shaft leads down inside to an 11-inch diameter rotor, which directs the airflow in one direction. A series of fixed stators underneath send the airflow slightly in the opposite direction—a counter-swirl effect that acts as a tail rotor on a helicopter to keep the platform from spinning, Tousley points out. Located beneath the stators is a series of box control veins, which are directed by the avionics pod. These veins orient and direct the vehicle in flight.

A small rugged tablet-size computer acts as the observer/controller unit for the MAV system, which includes two of the flight vehicles. A soldier uses a small metal stylus with a touchpad on the screen. The screen provides a small map display and real-time video from the sensors. Preflight mission-planning algorithms also are displayed. “A soldier enters the go command, and the vehicle autonomously launches on a mission,” Tousley maintains.

MAV can be dynamically reprogrammed in flight if the mission changes. Flight planning also includes up to 100 waypoints, and as many as 10 preplanned flights can be stored on the groundstation. Horizontal navigation position accuracy is 10 meters with 4-meter pressure altitude accuracy. The system uses inertial navigation and global positioning systems with selective availability anti-spoof module capabilities.

Through shaping and dampening technologies, Honeywell is seeking to reduce the aircraft’s noise level to 60 decibels acoustic (dBA) to make it inaudible at 100 meters. Initial operations began at 70 dBA, but that already has been reduced to 63 dBA with the ACTD goal anticipated before the return to Hawaii, according to Tousley. “We would like for MAV to be even quieter, and there are some things being done, but it will never be whisper quiet. It has an 11-inch-diameter propeller operating at 6,000 revolutions per minute.”

After final checkout at the contractor’s facility, nearby flight tests were conducted for vehicle performance validation before deployment. “It was determined that altitude, time on station and forward velocity requirements were being met,” Tousley acknowledges. The vehicles were sent to Hawaii. During the earlier demonstration there, a dedicated platoon was assigned. When MAV returns to Hawaii in October for military utility assessment, it is expected to continue with route and aerial reconnaissance objective security missions and will work in concert with Stryker vehicles to seek out and detect IEDs. The experiments also are being conducted to determine whether soldier recommendations to improve bugs discovered earlier have been addressed successfully.

The sensors are being changed on MAV, Tousley says. “In the first experiments at Schofield Barracks [headquarters of the 25th Infantry Division], we used a commercial off-the-shelf charged coupled device forward- and downward-looking camera with 512 x 512 square pixels in the focal plane. Since then, Sony’s new commercially available 10:1 optical zoom camera will fit the size, weight and power requirements for MAV. This new sensor will provide a 27-degree forward-looking field of view and a 54-degree downward-looking capability.

“The optical zoom feature of the Sony camera allows varying the field of view from very narrow to really wide, enabling MAV to hover at low levels for wide area observation or to fly higher and use the narrow optical zoom capability on the forward-looking sensor to stand off from potential threat areas and observe the enemy,” Tousley remarks.

The infrared sensor also is being changed to a similar field-of-view system. Soldiers decide before a mission whether to use a podded optical or infrared camera. The infrared device also can be used in daylight to help locate hidden enemies in areas such as tall grass from their body heat signatures.

Based on successful performance verification with the 25th Infantry Division in October, some 50 available flight vehicles being used for tests are likely to be shipped overseas to combat zones, Tousley says. The Army’s UAV program manager also is expected to pull MAV into the small unit UAV requirements document.

Instead of having only the Raven UAV, platoon-size units will operate with both a fixed-wing forward-flight platform and with a VTOL hover-and-stare capability. The observer/controller unit will be common for both MAV and Raven. After successful October demonstrations, MAV is slated to enter full-scale production by Honeywell for Army-wide use.

Troops Get Bird’s-Eye View
Hover-and-stare sensor platforms find enemy, unmask ambushes.

Improved micro air vehicles soon will be delivered to a platoon within the 25th Infantry Division in Hawaii. These upgrades are based on earlier user evaluations and soldier feedback at the division’s urban training site. Among improvements identified by soldiers are increased vehicle endurance, enhanced sensor performance and an improved observer/controller unit.

Indeed, this tiny unmanned aerial vehicle (UAV) will again be put to the test by soldiers in urban and complex environments during a variety of tactical operations. The micro air vehicle’s (MAV’s) ease of employment and ability to hover and stare show promise for numerous missions. These aerial platforms provide the platoon with better situational awareness and thwart confusion during tactical training engagements.

Division soldiers in earlier advanced concept technology demonstrations used MAV instead of sending troops to conduct end-run sweeping reconnaissance missions. They also launched the UAV to conduct aerial observations prior to driving convoy routes and on scouting missions to provide information on the location of opposing forces. During October 2005 tests, soldiers who were familiar with commercial video games found it easy to learn how to operate MAV.

The division selected five junior enlisted men—three privates first class, one private and a specialist—and prime contractor Honeywell Aerospace provided initial training on how to operate and fly the system, according to Lt. Col. Malcolm B. Frost, USA. He commanded the 2nd Battalion, 5th Infantry Regiment, during the test period. As part of a transformation, that unit is now the 3rd Squadron, 4th Cavalry Regiment, 25th Infantry Division. Deployed to Afghanistan in 2002, the colonel is a graduate of the U.S. Military Academy, West Point, New York, and holds a master’s degree from Webster University.

“The Army’s Infantry Battle Laboratory, Fort Benning, Georgia, coordinated and supervised MAV testing in concert with Honeywell Aerospace at the division’s military operations on urbanized terrain, or MOUT, site,” the colonel explains. He adds that instructors and operators handled maintenance and gained flight proficiency for about a week before a platoon conducted a series of tactical missions. That unit, since converted to 1st Platoon, B Troop, 3rd Squadron, 4th Cavalry Regiment, is commanded by 1st Lt. Mario A. Quevedo, USA. He also is an Afghanistan combat veteran.

“The platoon was made up of cavalry scouts even though the conversion was not final,” the colonel relates. “Some 80 percent of the platoon was composed of soldiers right out of basic training, which made it good for test purposes. The unit had two weeks of trial runs, which were full-on missions, and a week of executing tactical operations in reconnaissance of an urban area, assault of buildings, route reconnaissance, convoy escort and as a leader’s scouting tool.”

MAV also located and identified opposition force soldiers on the tops of or hidden behind buildings. This UAV’s capability enabled the platoon to confirm its scheme of maneuver and to avoid surprise or being flanked. The vertical takeoff and landing aircraft also was employed by the platoon to hover and check inside the second and third floors of buildings for possible concealed enemies. MAV was successful in confirming that routes of advance were clear as the platoon maneuvered toward its objectives, the colonel verifies.

“MAV’s use also included checking out courtyards and the opposite sides of buildings for enemy presence or obstacles, just as in Iraq,” Col. Frost says. “In some instances, the opposition force was detected with snipers atop buildings, and in others hiding behind structures. When opposition forces heard MAV coming, they often rapidly withdrew to other positions.”

While not quite sequential, the colonel continues, two MAVs were employed in near simultaneous use to maximize time on station for the sensor platforms. As one MAV was flying, another was readied for flight. When the first UAV was inbound to land, the second was already powering up for takeoff.

Approximately 25 MAVs were available for testing by the platoon. Some parts problems arose with prototype hardware, and one of the vehicles crashed. However, with the colonel’s combat experience and that of Lt. Quevedo, it soon became obvious that MAV could play significant roles in either Afghanistan or Iraq, they added.

“Even with limitations, such as time on station or the sensor’s inability to focus in some areas, the UAV has great utility. MAV is a bit bulky and unwieldy for infantrymen to carry, but we were able to cross-level the equipment and carry it,” Col. Frost notes. “But that doesn’t mean you can’t move it in a high mobility multipurpose wheeled vehicle to a designated point, dismount and carry it a couple of kilometers without a problem.” He adds that with the improvements being made, limitations should be overcome before division testing resumes within a few months. “I can see MAV being successful in Iraq or Afghanistan, and it certainly may prove useful in finding improvised explosive devices and helping to protect convoys,” he concludes. 


Web Resources
Defense Advanced Research Projects Agency Defense Sciences Office: www.darpa.mil/dso/index.htm
Honeywell Aerospace: www.honeywell.com/sites/aero
Aurora Flight Sciences: www.aurora.aero
U.S. Army 25th Infantry Division: www.25IDL.army.mil/index.asp


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