Dulles Addition Is Anything But Dull The Steven V. Udvar-Hazy Center – an extension of the Smithsonian Institution's National Air and Space Museum – will open in December (two days prior to the 100th anniversary of the Wright brothers' first flight in 1903) on a site at Washington Dulles International Airport. Direct airport access means additions to the museum's collection (like the Space Shuttle Enterprise) will not have to be taken apart and transported by truck in pieces to the new facility. The Center's impressive collection includes the Dash 80 prototype of the Boeing 707, the F-4 Phantom fighter jet and the B-29 Superfortress Enola Gay. In June 2003, an Air France supersonic Concorde passenger jet made its final flight to Dulles Airport, where it, too, will become part of the Center's collection.         The US$300 million Center is on a 176-acre (71-hectare) tract of land on the southeast side of Dulles Airport. An additional 50 acres (20 hectares) is available for future expansion of the museum. The aviation hangar section of the museum, under the curved roof, is 986 feet (300 meters) long, providing more than 760,000 sq. ft. (70,600 sq. m.) of exhibit and other space.         An economic impact study found that the museum complex would generate $1.4 million annually in new, direct tax revenue for Fairfax County and $939,000 to $1.25 million in indirect tax revenue.         Northern Virginia was not without competition for the project. "As the new international airport was being built in Denver, and as Air Force bases were going underutilized or being decommissioned in other states, there was interest expressed on the part of members of Congress in having us study alternate sites," says Lin Ezell, the Center's program coordinator. "Those studies set us back a little bit, but we looked at every legitimate [site] and compared them with what we were intending to build here. We also had to factor in the cost of moving the collection and the dislocation of staff that would be required if we moved far away from the home facility. In the end, when you add the numbers and consider all the ramifications of being at a distance from Washington, a free home wasn't really a free home."         What's more, says Ezell, an airport isn't a museum. "We require a tolerance for mechanical systems that are not required at an airport, for example. A museum exists to keep the artifacts around forever, so we have pretty tight tolerances on humidity and temperature."         For more information, visit www.nasm.si.edu/museum/udvarhazy/. – Mark Arend