Landing Makes the Mission

Written by Peter A. Buxbaum

SOTECH 2009 Volume: 7 Issue: 7 (September)

The Armed Services Are Looking To
Improve Their Ability To Expeditiously
Land Forces And Equipment
In Expeditionary Operations.

Unlike the days of the Cold War, when the U.S. military planned the pre-positioning of forces and materiel six months or a year in advance, today’s environment demands agility. And that means the capability to deploy forces to a hot spot within a matter of days. Today’s commanders work on timelines measured in hours instead of days or weeks.

That is why the armed services are looking to improve their ability to expeditiously land forces and equipment in expeditionary operations. This requires preparing the ground for the landing of aircraft in forward areas of operation.

Fixed wing and rotary wing aircraft each have their requirements for suitable materials for landing zones at forward airfields. Fixed wing aircraft require materials that are heat- and skid-resistant, among other attributes. Landing pads for rotary wing aircraft must be able to cope with the phenomenon of brownout from dust generation during landing and takeoffs.

The use of helicopters is increasingly being emphasized in forward expeditionary operations. The Marine Corps, for example, relies on smaller, lightweight units and heavy use of rotary aircraft such as the CH-46, CH-53, AH-1 and UH-1, and tilt-rotor V-22 aircraft.

Brownouts have already taken their toll on U.S. and coalition operations in Iraq and Afghanistan. In one 2005 incident alone, a U.S. Army CH-47D Chinook and 18 lives were lost due to brownout conditions. Experts estimate that three of four helicopter accidents in Southwest Asia have been caused by brownouts.

Brownouts occur when dust and foreign object debris (FOD) are thrown up by the helicopter rotor downwash and can blind pilots, erode helicopter rotor blades, and affect helicopters’ engines, filters and electronic equipment. The ability of rotary wing aircraft to hover above, take off from, and land on deserts, rocky fields and mountain tops makes them vulnerable to brownout.

A variety of materials and methodologies are available to alleviate these hazardous conditions. Matting material can be placed on the ground to prevent the updraft of dust and debris and the soil can be prepared with chemicals and other materials to reduce dust and strengthen its engineering properties.

To date, the workhorse of matting materials has been AM2, an aluminum extrusion product that has been around since the 1960s, and which has been used to accommodate the more stringent requirements of fixed wing aircraft landing strips as well as for rotary wing landing pads. But the military is looking to replace AM2 for both applications for a variety of reasons.

The Naval Air Warfare Center Aircraft Division Lakehurst recently released a request for information seeking alternative sources of a lightduty mat in support of its Expeditionary Airfield (EAF) program. The EAF concept seeks to land aircraft within an effective range of ground forces and strives for the construction of portable, reusable, forwarddeployed, and easily constructed airfields for the rapid introduction of air power.

“While AM2 mat is a highly capable medium-duty, battle-proven airfield surfacing system,” the announcement noted, “the substantial weight and cube embarkation profile of this system is slowly reducing the operational capability and feasibility of deploying this system for all applications. Some operational commanders have elected not to employ the use of the only airfield surfacing system in the inventory.”

The U.S. Army Engineer Research and Development Center (ERDC) has been conducting extensive research for a program it calls Joint Rapid Airfield Construction, or JRAC. “This involves constructing air strips in remote, austere environments,” said Gary Anderton, chief of ERDC’s airfields and pavements branch. “It could be in the middle of nowhere with a distinct lack of engineering materials like asphalt, rock and quality soil. The challenge is to build an airfield with little or no local industry support and under compressed timelines.”

Under such conditions AM2 is becoming an increasingly disadvantageous material. “The main reason we are looking into replacing AM2 is that, at 6.5 pounds per square foot, it is very heavy,” said Tim Rushing, an ERDC research civil engineer. “With lighter material we could put more volume on an aircraft and get more matting to a remote area faster.”

ERDC is searching for materials at least as durable as AM2 but with a weight reduction to a maximum of 3.8 pounds per square foot and which also has other necessary attributes such as durability; fuel spillage, heat and skid resistance; and the ability to fit properly on a standard 463L cargo pallet. ERDC is evaluating nylon polymers and aluminum materials, among others, according to Rushing.

There are several existing matting and soil preparation products currently on the market and in use by various U.S. military branches. The Mobi-Mat, marketed by Deschamps Mat Systems Inc. of Little Falls, N.J., was originally developed in France and was evaluated for U.S. use by the Pentagon’s Office of Advanced Systems and Concepts in 2002. The U.S. Marine Corps was the first to buy it. Since then, Mobi-Mat has been used by the Army’s 101st Airborne Division and the 10th Mountain Division.

“The Mobi-Mat helipads are used to reduce brownouts and build forward operating bases enabling helicopters to operate closer to the battlefront,” said Alex Hamon, Deschamps’ defense sales manager.“This expedient capability shortens the forces’ response time and provides the warfighter increased flexibility for landing zones and medical evacuations.” The Mobi-Mat is a light tri-dimensional polyester mesh that comes in rolls of 13 feet, 11 inches by 33 feet, weighing 176 pounds. Two men can transport the roll and three can unload, unroll, connect and stake it down.

“The Mobi-Mat installation rate is a minimum of 10,000 square feet per hour for a 16-man team on an eight-hour shift, using only common handheld or powered tools,” said Hamon, and the same goes for its removal rate. “The Mobi-Mat system has the ability to accomplish this process of installation, removal and re-installation a minimum of three times in any 12-hour period, including all applicable anchoring installation and removal iterations.”

CGear, a company based in Port Melbourne, Australia, provides lightweight flooring composed of two layers of woven polyethylene mesh sewn together, with reinforced binding at the edges. The product, known as CGear Tactical Helimat, is designed to be used on the ground, which is relatively flat, said the company’s chief executive officer, Glen Sinclair-Gibson.

The CGear Tactical Helimat includes multi-layered, open-weave polyethylene mesh, which prevents brownout by inhibiting the sand and dust underneath the mat from coming back up even when being pounded by a powerful rotor downwash.

“The product was originally designed as a beach mat,” explained Sinclair- Gibson. “The holes in the polyethylene mesh are very fine, allowing sand to fall through them but at the same time preventing the sand from coming back up. One of the guys in the company flew helicopters so we put a prototype together for use as a landing pad. When we tested we found again that the sand went through but didn’t come back up.”

From that point CGear was invited to demonstrate the product to the U.S. Marine Corps and has been awarded two contracts since 2005 to deliver a total of 2 million square feet of the product.

The size of each segment is 20 feet by 20 feet. Sizing of the landing pad depends on the rotor span of each particular helicopter, with dimensions of the helipad approximating 33 feet wider than rotor span, in all directions. The 100 foot by 100 foot helipad configured with 25 segments, suitable for a Black Hawk, Huey or Super Puma, can be contained in less than 211 cubic feet. A Chinook would require a configuration of 6 by 6 Helimat segments, or 120 feet by 120 feet.

The shape of the CGear Tactical helipad can be customized to suit individual requirements, said Sinclair-Gibson, and it can be quickly and easily moved from one task to another. It can be packed up and deployed at forward arming and refueling points, increasing helicopter time over target. The fabric’s weave technology prevents it from tearing or fraying, and it is resistant to fuel and oil spill damage.

The CGear Tactical Helimat has been extensively tested by the U.S. Marines and other military services, according to Sinclair-Gibson. “In U.S. Marine Corps trials at Navair Lakehurst Airbase, the CGear Tactical Helimat stood fast, even when the Marines attempted to lift and rip apart CGear’s joining and anchoring systems using a Huey, a Black Hawk and a Super Stallion helicopter,” he said. “There was no risk of the Helimat being sucked up and tangled in the rotors when correctly installed.” Testing of the Tactical Helimat in Abu Dhabi in November 2007 using a Chinook helicopter also confirmed that the product eliminates brownout and FOD.

Soil stabilization products improve the properties of soil to make it amenable for aircraft landing purposes. These products are sometimes used by themselves but also in conjunction with matting materials. “We refer to soil stabilization products as improving the engineering properties primarily by increasing the strength of soil,” said Kent Newman, an ERDC research physical scientist. “There are numerous commercial products used for stabilizing soils.”

Bob Vitale, CEO of Midwest Industrial Supply Inc., echoed that view. “In my view, the preferred method must stabilize or modify the surface area, eliminate dust and FOD, must be simple with ease of handling and use, and must be able to be deployed fast.” Midwest specializes in dust control, soil stabilization and erosion prevention with a range of products designed to meet specific requirements.

The company acknowledges that three of its products are currently being used in Iraq and Afghanistan: EnviroKleen, EK35 and Soil Sement.

“Envirokleen and EK35 are both new technologies and combine synthetic fluid and two unique binder systems that create surface stability and prevent surface fines becoming airborne by durably bonding particles and aggregrate together, said Vitale. “These products do not leach out in high temperatures, providing longlasting effectiveness; these products do not create any hazard for rotary wing aircraft during either landing and takeoff; rotor wash will not destabilize the surface.

“These products are 100 percent active and spray-applied to the area as delivered to the site,” he added. “No water is added, and the treated area can be used immediately.”

“The basic definition of soil stabilization is modifying the existing soil to increase its load-carrying capacity,” noted Shane Williams of Soilworks LLC in Gilbert, Ariz.

“The bearing capacity of bare dirt can be as little as 70 to 200 pounds of pressure,” said Williams. “With our product the bearing capacity can be boosted to 500–1,000 pounds depending on the soil type. The polymer coalesces with aggregate and creates a matrix in which soil is held together mechanically.”

The product is also biodegradable and photo-degradable. “Eventually the product dissipates,” said Williams, “and that makes it environmentally friendly.” Soilworks’ primary military customers are the U.S. Air Force and Marine Corps. It also provides its product to other U.S. and international military organizations.

When ERDC investigated soil stabilizers for its JRAC program, the goal was to find a simple product that was locally available in most areas of the world, limiting the necessity of transporting large amounts of heavy material. “At first we thought we would be able to find epoxies and polyurethanes, but for different reasons they didn’t meet our needs,” said Newman. “Then we went back to Portland cement.

“Cement proved to be a better answer because it is universally available, while epoxies and polyurethanes can be difficult to find in quantity. We felt it was a useful material because it can be obtained locally and it reacts with a minimal amount of water,” said Newman. “Even if there is excess water in the soil, we can use that to our advantage in some cases.”

ERDC then started investigating ways at improving soil-cement properties and reducing the volumes necessary to be carried into theater. “Because of cement’s heavy weight, we wanted to reduce the required dosage as much as possible,” said Newman. “The best way we found was to add fibers to the soil and then blend the cement in the soil. The cement increases the strength of the soil, and adding fibers improves the modified soil’s toughness, which reduces the amount of cement required.”

ERDC tested different types of fibers and found the best, because of its availability and low cost, to be polypropylene fiber of 1 to 2 inches in length.

ERDC’s soil stabilization findings were incorporated into the JRAC program’s final demonstration project in 2007, which involved the complete construction of a C-17 capable runway and two aircraft parking aprons at Bradshaw Field Training Area in Australia’s Northern Territory. In Australia, a 4,100-foot by 90-foot runway was constructed in only 16 12-hour work days. In addition, two 5,000 square-yard parking aprons and two 1,400 square-yard taxiways were constructed with fiber-cement stabilization in just 40 hours.

“No one in any military anywhere comes close to this capability,” said Newman. “Our goal was a 50 percent reduction in construction time and logistical effort compared to traditional methods, and we achieved that and then some.”

As for JRAC’s legacy, “It is now in the hands of the Army’s acquisition community,” said Newman. ♦

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