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Robotic Resupply

Unmanned K-MAX’s Afghanistan Demonstration

By David Axe

In early 2012, a Sikorsky CH-53D Sea Stallion helicopter belonging to Marine Heavylift Squadron 363 out of Hawaii crashed in southern Afghanistan's Helmand province. Six Marine crewmembers died — the greatest single loss of life for the Marines in Afghanistan this year.

The crash, reportedly the result of mechanical error, was only the latest in a long chain of helicopter losses for U.S. forces. The Marine Corps believes it has a solution to this problem in the form of a robotic helicopter. It’s not that unmanned aircraft don’t crash. But when they do, usually nobody gets hurt.

A demonstrator version of the Marines’ planned full-spec robotic supply helicopter had already been flying for several weeks in Helmand when the CH-53D went down. A pilotless version of the twin-rotor K-MAX, co-developed by Kaman and Lockheed Martin and operated by a combined Lockheed-Marine crew, was still hard at work in Afghanistan four months later. The real-world test is laying the groundwork for a follow-on supply UAS that should fly farther, faster, with a heavier load and with more sophisticated controls.

Helicopters are indispensable in Afghanistan. Due to the rugged terrain and lack of good roads, many smaller combat outposts are resupplied entirely by helicopters supplemented by fixed-wing airdrops.

But the heavy reliance on helicopters comes at a cost. In more than a decade of fighting since 9/11, the Army, Navy, Marines and Air Force have lost more than 400 rotorcraft and 600 crewmembers in shoot-downs, crashes, hard landings and ground accidents.

The Marines began weighing options for pilotless aerial resupply as early as 2008. The amphibious combat branch considered four robotic platforms — the Mist Mobility SnowGoose parafoil and three rotorcraft, including the Northrop Grumman Fire Scout, the Boeing Hummingbird and the K-MAX.

To turn the manned K-MAX into an unmanned vehicle, Lockheed and Kaman added satellite and line-of-sight data-links, a mission-control computer, redundant flight-control computers and actuators. With no crew but extra equipment for remote operation, the robo-K-MAX boasts essentially the same performance as the manned version: 5,500-pound payload, 80-knot cruise speed and a range of 250 miles.

In 2009, the Corps selected the Lockheed-Kaman and Boeing teams for demonstrations under separate contracts valued at $46 million and $30 million, respectively. The Hummingbird was grounded following a crash in Belize in 2010, delaying the Boeing demonstration. The Boeing contract eventually lapsed, leaving the K-MAX as the de facto winner of the cargo-‘bot demonstrator contest. “We are committed to providing the Marine Corps with the life-saving unmanned capability of our proven airframe,” says Sal Bordonaro, division president at Kaman.

After August 2011 field trials in Arizona, in November Lockheed Martin and Kaman deployed two pilotless K-MAX aircraft to Afghanistan with the 3rd Marine Air Wing for a six-month war-zone trial. The first combat resupply sortie took place on 17 Dec.

Combat Ops

The Marines and industry have not specified exactly where in Afghanistan the two K-MAX UAS were based and how many people it took to operate them, but it's possible to make educated guesses. Kandahar Air Field in Kandahar province, adjacent to Helmand, is the main air hub for southern Afghanistan. The airfield is the apparent setting of a team photo released by the Marines that shows around a dozen civilian contractors and fewer than 10 Marines posed in front of a K-MAX.

The team apparently included several officers who serve as mission commanders plus enlisted air vehicle operators. According to press reports, some air vehicle operators were staged at forward bases, where they helped steer the copters during the final moments of a supply run. But for most of a mission’s duration, the K-MAX aircraft autonomously followed preprogrammed waypoints. 

“A ground controller uses a ruggedized laptop with command-and-control software to develop and upload a mission flight plan to the aircraft’s onboard Mission Management Computer prior to launch,” says Lockheed’s Jeff Brown. “The controller can upload new mission plans at any time during flight.”

When in view of an airfield or outpost, the K-MAX was typically controlled via a line-of-sight radio antenna. Between sites, connectivity was maintained by satellite.

In the first three months of operations at Kandahar, the K-MAX systems flew just one mission per day, on average. A typical mission lasted just over an hour, meaning the K-MAX was probably ranging just 50 miles or so from its home base for most deliveries. “The requested loads are generally 50 percent of lift capacity,” says 2nd Lt. Jose Negrete, a spokesman for the 3rd Marine Air Wing.

In about 100 missions conducted between mid-December and late February, the two K-MAX vehicles delivered an estimated 275,000 pounds of cargo — 2,750 pounds per mission, on average, Negrete says. “Icing, lightning and strong winds have been the major weather elements that we have encountered during the deployment,” he added. “Rain, dust and low visibility are not really an issue. This aircraft works well at night and is relatively quiet compared to other military helicopters.”

Most of the missions were flown at night and at high altitude in order to minimize the risk from ground fire, according to Marine Capt. Caleb Joiner, one of the mission commanders.

As the operators grew more comfortable, the sortie rate increased, says Bettina Chavanne, a Lockheed Martin spokesperson. By April, the K-MAX helicopters were flying up to six missions per day — and the average load had increased to more than 3,000 pounds, still more than a ton short of the maximum. The robots required less than an hour of maintenance per flight hour, Chavanne says.

Despite being an experimental system, the unmanned K-MAX was included in the Marines’ routine aviation tasking system, which pairs up mission requests with available aircraft. “In that respect, we are no different,” Negrete says.

Faster, Farther, Smarter

The Marines want to follow K-MAX with a more capable cargo UAS within the next six years. According to a Lt. Col. Brad Beach, unmanned aerial system coordinator at Marine headquarters, the new cargo system should have a top speed of at least 240 knots and a range of 350 miles, both a significant improvement compared to the K-MAX. But the new vehicle’s payload capacity should be at least 1,500 pounds, a little more than a quarter what K-MAX can haul.

Unlike the K-MAX, the new UAS should be highly autonomous and also capable of operating from a ship.

The Navy, on behalf of the Marines, launched the follow-on Autonomous Aerial Cargo Utility System (AACUS) program late last year. The goal is to produce an unmanned aircraft to “provide affordable and reliable rapid-response cargo delivery to distributed small units,” according to program document.

The Marines envision the new cargo UAS as a sort of smarter, faster, farther-flying, shipboard K-MAX. But to the Navy, the airframe is almost beside the point. To the Navy, the most important lesson from early pilotless resupply trials is that the control system matters more than the airframe.

To that end, the sailing branch is approaching AACUS as a universal control system and sensor suite that can be installed in a wide range of different vertical takeoff and landing airframes, potentially ducted-fan designs. “We want to show that we can plug and play across different rotorcraft and VTOL aircraft and get some level of guaranteed performance,” says Missy Cummings, the program director.

If the project works out as planned, the AACUS supply UAS will fly between sites with no direct human control, scanning their surroundings, detecting obstacles and enemies, and even zooming in for quick deliveries after spending only seconds mapping out a landing zone using lasers, radar or other sensors. The ‘bots will only need people to tell them when and where to deliver something, by tapping out a few commands on a smart tablet such as an iPad. The new systems will not require a human controller during the terminal phase, as K-MAX often did.

The program is taking an incremental approach to developing the universal control system. The first step is to select two contractors to build early prototypes, matching Cummings’ control technology with existing aircraft designs. Lockheed Martin, Boeing and Northrop Grumman are likely bidders. The best two best teams will compete in an increasingly realistic set of tests starting in 2014, swapping the AACUS “brains” across multiple airframes. By 2018, Cummings wants to pick a winner — and start building production models for combat use.

If within the next six years the Marines begin fielding large numbers of cargo drones capable of highly autonomous operations that minimize the risk to American lives, it will be because the unmanned K-MAX proved it was possible.

David Axe is a freelance writer based in South Carolina and the author of “WAR BOTS.” He blogs at www.warisboring.com. This article was reprinted with the permission of AUVSI.org.

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