Cooling Tech for Army Aviators Is Out of Reach for Grunts
A U.S. Army Blackhawk helicopter simulates an assault.
CREDIT: U.S. Army
When the U.S. Army invaded Iraq in 2003, its helicopter crews had just begun to wear a water-cooled vest to fight overheating during long combat missions. Now, a decade after the Sept. 11 attacks, the same vest is worn by the human operators of war machines ranging from Black Hawk helicopters to Abrams tanks and Stryker armored vehicles.
It's a different story for the soldiers who tough it out on the ground when they patrol in the extreme heat found in parts of Iraq and Afghanistan . Most adaptation to local climates "is done naturally by the human body," said David Accetta, a retired lieutenant colonel at the U.S. Army Natick Soldier Research, Development and Engineering Center in Natick, Mass.
"After 18 months in Iraq and 15 months in Afghanistan, I can tell you that as much as we would like to have this type of equipment for our troops, the technology isn't there yet," Accetta said. "In the end it comes down to body conditioning."
That has not stopped the U.S. Army from eying new technologies that could help soldiers adapt to hot or cold conditions. This year, it put out the call for a new clothing material that could respond to temperature swings between 73 degrees F (23 degrees C) and minus 22 degrees F (minus 30 degrees C). By using textiles or fibers that can change in thickness, the proposed clothing could keep soldiers comfortable in torrid conditions and still provide the protection of multilayered cold and wet weather gear.
Still, making that climate-controlled future possible may prove tricky, if the history of the cooling vest worn by Army aviators and vehicle crews serves as any lesson.
From jungle to desert
During the Vietnam War, U.S. Army helicopter crews had less of a problem with overheating because they wore less gear than their modern-day counterparts helmet, flight suit, gloves, survival vest and maybe "flak vest" or "chicken plate" body armor designed to stop shrapnel or bullets. But the gear was still very hot, according to Vietnam veterans in the U.S. Army's Air Warrior program.
In response, Bell Helicopters designed a blue canopy to cut down on cabin heat in AH-1 Cobra attack helicopters, and later introduced the first helicopter air-conditioning system. The Hughes OH-6 Cayuse flew with its doors removed. Crews of the Bell UH-1 "Huey" that transported troops and evacuated the wounded flew with cabin doors opened and pilot windows down.
By the time the U.S. Army geared up for the Iraq war in 2003, its aviators wore anywhere between 65 and 70 pounds of gear, including better protection against enemy fire. Combat missions in the extreme desert temperatures added to the overheating problem.
Keeping it cool
A solution came in the form of the Microclimate Cooling System (MCS). Studies in the 1990s had shown that helicopter crews wearing full chemical protective gear could stand only about 1.6 hours in conditions of 125 degrees F (52 degrees C) and 14 percent relative humidity without cooling. Wearing the MCS vest allows pilots and crew to endure such conditions for up to 5.7 hours.
"Without this cooling system, we wouldn't be able to fly over two hours," said Lt. Col. Ian Klinkhammer, an Air Warrior product manager.
The system's cooling power comes from a 13-pound vapor compressor similar to the technology used in refrigerators and air conditioners. That unit is attached to the inside of helicopters so that it can pump chilled water through an umbilical to small tubes embedded in the vest worn by an aviator or vehicle crew member.
"The MCS gives an improvement in mission endurance of 300 to 400 percent," Klinkhammer told InnovationNewsDaily.
Since 2003, the technology has spread to 85 or 90 percent of the U.S. Army's helicopter crews, as well as the crews of Abrams tanks, Bradley fighting vehicles and the newer Stryker fighting vehicles. The U.S. Navy has also adopted the system for its Sh-60 Seahawk and CH-53 Sea Stallion helicopters.
Making it smaller
Not all helicopter crews can easily use the current cooling system. Crew members in the rear of Blackhawk and Chinook helicopters move around a lot and don't want to be tethered to the electronic cooling unit. OH-58D Kiowa Warrior helicopters could not make the space, weight or power available for the system, and so they fly with doors removed.
Air Warrior's new Air Soldier program looks to remedy these types of situations by creating a wearable version of the system, so that aft crew members don't have to drag an umbilical behind them as they move around performing their duties. The new Air Soldier program also aims to reduce weight and bulk by 25 to 40 percent as compared with the existing Air Warrior vests.
"We want a lightweight, untethered electronic personal cooling system integrated with the crew member's survival vest," Klinkhammer said. "We want to get it down to 3 or 4 pounds so that the aft crew member can move about the aircraft unencumbered and dismount the aircraft for short periods without losing their cooling capability."
The Air Warrior program did initially consider technologies that use phase changes or evaporation to keep helicopter crews cool, but such materials remain out of reach for practical use because of limits in how much cooling they can maintain over long missions. That may change over the next 10 years.