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Air support

Inflatable beams replace metal frames for wide span shelter

Inflatable arches or air beams can “blow up” various military shelters within minutes, and give the Army and Air Force a faster, simpler alternative to metal frames.

The Wide Span Air Beam Shelter is the latest product using air beam technology to be demonstrated by the Fabric Structures Group at the U.S. Army Soldier Systems Center (Natick). The shelter—used for temporarily storing aircraft, vehicles and supplies—reduces logistics involved in providing field maintenance, and dramatically cuts the time it takes to set up and break down.

Wide Span Open Air Beam Shelter
The Wide Span Air Beam Shelter uses braided fiber construction, the material composed of durable yet bendable Vectran fibers that give high load-carrying capability and necessary curvature.

The Large Area Maintenance Shelter (LAMS) used since Operation Desert Storm takes 10 people a week to set up, but the air beam shelter will reduce that time to two days, said Jean Hampel, project engineer for air beam technology.

“When you need to rapidly deploy to follow troop movement or establish a port, you can’t wait a week,” Hampel said. “You need a sheltered environment, especially because today’s composite materials in aircraft require a protected environment for repair. With better maintenance and reduced downtime, the more aircraft you have available for the mission.”

Air beams for the wide span shelter reduce deployment time by 75 percent, weight by half and volume by a quarter compared to a similar metal frame shelter, but getting there was a challenge, according to Hampel.

A compressor fills the tubes and monitors pressure.

Traditional commercial inflatable products, such as aircraft escape slides or inflatable boats, are constructed of flat coated fabrics cut and manufactured to the intended shape by stitching, adhesive bonding or thermally welding fabric pieces together. The technique is laborious, and air seeps through seams and abrasions.

“(The products) feel squishy because they can’t go much over 5 pounds per square inch of air pressure,” Hampel said. “If you make (an air beam) too big, it ends up being as heavy as metal. If the pressure is too high, it can blow out.”

From the first low-pressure, leaning inflatable arches in the 1970s, engineers learned they needed to eliminate seams, reduce surface area, increase pressure and develop automated manufacturing processes.

anchored tubes
Tubes are anchored to the ground and inflate in about an hour.

They needed a high-strength sleeve, and the breakthrough came with braided technologies from Vertigo, Inc. and industry partner Fiber Innovations, Inc., and woven textile technologies from Federal Fabrics-Fibers, Inc.

Seamless, continuous tubular laminates can now be produced. The braided layers crossover at a slanted angle as opposed to a 90-degree angle, stretching out when filled with air. The wide span shelter uses the braided fiber construction, the material composed of durable yet bendable Vectran fibers that give high load-carrying capability and necessary curvature.

Air beams contain an inner liner, much like a tire inner tube, to hold the air while a tough protective coating helps prevent damage and degradation.

Wide span air beam technology doubles the spanning capability of seamless air beam technology demonstrated in smaller shelters.

inside the Wide Span Air Beam Shelter
At 80 feet wide, the shelter allows units to temporarily store aircraft, vehicles and supplies.

Tube pressure is now 30-80 pounds per square inch, with 80 pounds used in the wide span shelter for greater load carrying, Hampel said. The high pressure allows designers to make a smaller tube. Less surface area reduces the chances for leaking, and less material means a lighter weight.

High pressure creates a rigid structure under load, but it bends rather than breaks when overloaded. The 80-foot-wide and 33-foot-high wide span shelter is designed to withstand 110 mph winds and hold snow up to 20 pounds per square inch.

Four people can set it up without the aid of ladders or other heavy equipment. Once the tent and air beams are rolled out, fastened to each other and anchored into the ground, an inflation system pumps up the tubes to its setup height in about an hour, Hampel said. Reaching final pressure takes slightly longer. Tubes at the ends can be substituted with metal poles to get most of the benefits of air beams without the extra cost.

Hampel said the goal is to transition the wide span shelter to Natick’s Product Manager-Soldier Support for engineering development. This new air beam technology is already being used for the Chemically and Biologically Protected Shelter developed at Natick. Other related items under development include the Air Force TEMPER tent-sized shelter and the Small Tactical Air Beam Tent.

Beyond shelters, the inflatable technology has military and commercial applications for products such as munitions barricades, fuel or water containers, and space antennas.

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