The researchers at Natick are also working on portable buildings that are made of what are essentially large, high-strength textile balloons. Called air beams, these building materials would allow a team to build a structure large enough to hold airplanes in a fraction of the time a conventional metal structure would take. The largest air beams, about 0.75 meters (2.5 feet) in diameter and 24 meters (78 feet) long, are so rigid that you can hang a heavy truck from one. Yet they can be packed into a truck. Whereas a conventional metal hangar takes ten people five days to set up, one made of air beams can be sct up by six people in just two days.