NATICK, Mass. (May 29, 2014) -- Helicopter pilots have for years kept cool by plugging into aircraft-mounted microclimate cooling systems, but their crews have used them less frequently to avoid becoming entangled in the tethers that connected them to the systems.
That's why researchers at the Natick Soldier Systems Center have been testing the Light-Weight Environmental Control System, or LWECS, a body-worn microclimate cooling system that allows crew members to move around inside the aircraft without tripping on tethers, and to exit the aircraft while still being cooled.
"Basically, it's a small refrigeration device," said Brad Laprise, a mechanical engineer with the Warfighter Directorate, Natick Soldier Research, Development and Engineering Center, or NSRDEC. "It's the same technology that's in your air conditioner or in your refrigerator, except instead of conditioning air, it chills a fluid. And then it pumps that fluid through a tube-lined cooling vest."
The cooling unit is a cylinder 3 1/2 inches around that connects to a cooling vest and provides 120 watts of cooling. The vest has approximately 110 feet of tubing through which fluid can pass, and it is worn against a Soldier's skin. The system is powered by a plate-like conformal battery that can fit inside body armor.
"So we're hoping that this small, lighter-weight system would give them a lot more autonomy in the rear of the aircraft," explained Laprise, "and to allow them to get the cooling when they need it."
Researchers from NSRDEC and the U.S. Army Research Institute of Environmental Medicine, or USARIEM, working with Product Manager Air Warrior, have been testing LWECS at Natick's Doriot Climatic Chambers. With the assistance of volunteers wearing MOPP 4 chemical-protective gear, they have been simulating 11-hour missions in desert and jungle conditions.
"We've been living in the desert for the last 20 years, but we also know that the Pacific Rim is the next area that we're looking at," said Bruce Cadarette, a research physiologist with USARIEM's Thermal and Mountain Medicine Division. "We've been providing microclimate cooling for the pilots for 16 years now. It made them be able to prolong their mission, their endurance time, and able to perform at a higher level."
The hope is that their crews will be able to realize similar benefits with LWECS, without being tethered to an aircraft-mounted system.
"Right now we're looking at crew chiefs who have to load and unload cargo and maintain the cargo," Cadarette said. "They also have to sit as rear gunners in some of the helicopter frames.
"The other people that we're concentrating on are the medics, who have to fly out in the back of the helicopters, and who have to go out and treat wounded in the field, load them onto stretchers, (and) get them onto the back of the helicopter."
Over two weeks, the five test subjects each took two turns in the simulated desert conditions and a pair in the jungle conditions -- one using the cooling system and one without it -- in the chamber.
"It's really a critical step, proving out the efficacy of this microclimate cooling technology and the capability that it provides," Laprise said. "If we don't have Doriot, we need to find somewhere else to do it, and I'm not so sure there's a place in the world where we can do this testing. So it is absolutely critical that we have this capability here at Natick."
The cooling systems and the volunteers performed well, according to the researchers.
"We really haven't had any issues with (the LWECS)," said Laprise, who looked at the fluid temperature before and after it passed through the system, and monitored flow rate. "By and large, they've been very reliable."
Cadarette said the same for the volunteers, who sat for 50 minutes and walked for 10 minutes each hour to simulate missions during which they would get off and back on the aircraft.
"A lot of the day is not heavy work, but for brief periods of time, they work very, very hard," Cadarette said. "Now you've got a battle between your muscles calling for blood in order to exercise and your skin calling for blood in order to cool off."
During the 11-hour sessions, Cadarette and his team monitored core and skin temperature, heart rate, and everything that went into or came out of the subjects' bodies.
"From our point of view, we monitor everything we can, physiologically," Cadarette said. "So now we know, are you doing better with the cooling?"
Cadarette has a great deal of data to sift through, but the early indications are that the LWECS is making a difference.
"Physiologically, we're seeing that their body core temperatures are lower, their heart rates are lower," Cadaratte said. "So far, what I'm seeing looks really good. I think we can show that the cooling portion of this does what we're asking of it."