More Air and Space
Although it owes its very existence to aviation, the National Air and Space Museum was operating in restricted air space.
NASM's flagship building on the National Mall in Washington, D.C., which opened in 1976, had room to display only 10% of its collection. The new Steven F. Udvar-Hazy Center, located 28 miles away at the edge of Dulles International Airport, will enable NASM to display about 80% of its collection. Most of the collection has been kept in a preservation, restoration, and storage facility in Suitland, Md.
"Udvar-Hazy's open, hangar-like design allows us to display aircraft that could not fit through the doors of the Mall building," says NASM director J.R. Dailey. Lin Ezell, NASM project coordinator, says the primary advantage of the new annex, popularly known as "America's Hangar," is its ability to accommodate larger air- and spacecraft.
The 1,000-foot-long, 250-foot-wide hangar and its associated public amenities building — which includes a museum store, food court, administrative offices, and IMAX theater — opened last December 15, two days before the 100th anniversary of the Wright brothers' first successful heavier-than-air flight.
The architect was St. Louis-based A/E Hellmuth, Obata & Kassabaum, which also designed the Mall building — an assignment that led to the opening of its Washington office.
The hangar's shape, reminiscent of structures built to house dirigibles, allowed designers of the 49 million cubic foot facility to create a high ceiling within a relatively economical structure, according to HOK design principal Bill Hellmuth. Unlike a rectilinear space, the structure becomes an artificial sky that removes the sense of confinement created by a ceiling. "We were able to have a ceiling 10 stories high — far enough away from the planes that it became an appropriate backdrop," he says. One design scheme envisioned a roof rising to 130 feet; in the final design, it tops out at 103.
The British/French supersonic airliner Concorde, retired from service last year, is among the most prominent displays in the commercial aircraft section of the Udvar-Hazy Center.
Hellmuth says the Udvar-Hazy design was influenced by a National Building Museum exhibit of models of 21 dirigible hangars — structures so huge that, if they were not internally conditioned, could experience the formation of clouds.
Let there be light, but not too much
Udvar-Hazy differs notably from its predecessor with regard to its use of light and daylighting. The Mall building was one of the first air museums that placed aircraft adjacent to large windows or skylights, in order to let the artifacts be seen with the sky as a backdrop. But experience has shown that a high level of such light degrades features such as fabric or leather items in cockpits.
Charles Lindbergh's flight coveralls, which were exhibited in an intensively lit display case at the Mall building, provide an example of such deterioration. When they lifted its fur collar, curators became aware of extensive fading in the garment's exposed area. Original glazing at the Mall building was subsequently replaced with glass that has a greater UV-filtering capability.
Udvar-Hazy's glazing is confined to arcs of glass at each end of the hangar that follow the profile of the barrel vault, and windows only 1½ feet high at alternate building bays on the east and west elevations. Interior light fixtures attached to light shelves below these windows direct light to the ceiling plane, reinforcing the appearance of a sky dome.
Although it is not apparent to visitors, the overall light level in the hangar is only 15 foot-candles — only a fifth of the intensity in the center's office areas. Task lighting highlights the exhibits themselves.
The virtually imperceptible transition from outside light levels to the low brightness inside the hangar is facilitated by a clerestory window at the entrance of the public amenities building. This window decreases in height from 30 feet to 6 feet along the entrance corridor, allowing a visitor's eyes to adjust to the change in light intensity.
The hangar is supported by 21 triangulated trusses, spaced 50 feet apart. They are 17 feet wide at the base and 345 feet long, rise 105 feet above grade, and span 230 feet. All trusses are designed to accommodate suspended loads of more than 22,000 pounds, and one truss supports six aircraft with a combined weight of 14,000 pounds.
Each truss has three segments — two end pieces each weighing 30 tons, plus a center section. Due to their size, they had to be assembled on site. Within two-and-a-half days of the components' arrival from the Canadian fabricator, the end sections were assembled and ready to be erected — with decking already attached, according to Paul Dickens, senior project manager for construction manager Parsons Brinckerhoff Construction Services Co., New York.
Triangulated trusses support the museum’s roof, air ducts, and some of its displayed aircraft. The hangar’s 21 trusses are engineered to carry suspended loads of more than 22,000 pounds.
Due in part to a shortage of available welders, the original intent of welding the truss components was abandoned in favor of a bolting plan. This saved $370,000 and maintained the construction schedule, Dickens says.
The trusses were erected in four-bay assemblies. Some of the roofing was installed during on-grade assembly. Roofing supported by the center truss sections was installed overhead.
"Regardless of delays in the entire program, we had to make the Wright anniversary date," says Dickens. Schedule disruptions included the loss of 75 workdays due to precipitation (a 22-inch snowfall damaged major electrical equipment) and one of the wettest summers in 50 years
The immensity of the hangar is indicated by the size of its components. The aircraft doors at each end are 47 feet high and 160 feet wide. Assisted by 3,000-pound counterweights, two small electric motors are able to open and close them. Inflatable gaskets at the door edges provide a seal to help maintain the hangar's required temperature and humidity levels. The museum requires strict stability control of temperature (70 F) and humidity (45–50%).
A 164-foot-tall observation tower replicates the layout of control towers at many airports, with an upper observation level above an enclosed level that houses controller equipment. From the observation level, visitors watch planes arrive and depart Dulles Airport. On the level below, they can see airplane icons on a radar screen disappear as planes touch down on a runway.
The hangar is clad with a Hypalon single-ply roofing system, while the IMAX theater and the observation tower are clad in aluminum.
A trench system for the distribution of electrical and communications services is incorporated into the hangar's concrete floor, which has a maximum thickness of 15 inches.
No forced routing
Visitors enter the Udvar-Hazy Center 15 feet above the main level, as if they were on the departure level of an airport. They first come face-to-face with the Lockheed SR-71, the world's fastest jet-propelled aircraft. The space shuttle Enterprise is seen in the background.
A descent to the main level is via a ramp with a gentle slope of less than 5% that accommodates a large volume of visitors, including those in wheelchairs or with baby strollers. After traveling the length of the main floor, visitors can take the elevator or stairs up to two mezzanine levels. They then obtain a new perspective on aircraft previously seen at a lower level, or get close-up views of planes at higher levels. Aircraft are positioned at various heights, but primarily at floor level and at 25 and 42 feet above the floor.
High-visibility aircraft include the Enola Gay, the B-29 bomber that dropped the first atomic weapon on Hiroshima, Japan, in 1945; the British/French Concorde supersonic airliner, which was retired from service last year; and Space Shuttle Enterprise, the first space shuttle orbiter.
Other aircraft on display include the Boeing Dash 80, the prototype for the 707, and the Clipper Flying Cloud, the only surviving Boeing Stratocruiser and the first airliner to have a pressurized cabin.
Walter Urbanek, HOK project manager, notes that the museum's circulation plan allows visitors to remain on a single level to view the major attractions in a short time, or to wander and find vantage points for viewing specific exhibits. This random access approach contrasts with the thematically or chronologically driven circulation pattern of the Mall building's 23 galleries.
Congress approved $8 million for the design of the center in 1993, but stipulated that no Federal money be used for its construction. The state of Virginia provided $40 million for access roads and other infrastructure.
A large site adjacent to a major airport was a prerequisite for the project, to allow some exhibits to be flown directly to the site. That's how the Concorde arrived last summer.
Construction was originally to begin in December 1999, but funding problems delayed the release of construction documents until May 2000. Because bids received in September 2000 exceeded available funds, a revised package of base bid and alternates was issued in January 2001. In April 2001 NASM authorized the start of construction. The general construction contract was awarded to Hensel Phelps Construction, Greeley, Colo.
Phase II planned
Planned additions to the Udvar-Hazy facility include a 57,000-sf archives area, a 56,000-sf study collection area, a 65,000-sf restoration area, where visitors will be able to watch technicians at work through a glass wall.
Phase II will increase the facility's size from 506,000 to 684,000 sf, but it is contingent on funding availability.
The center currently has 82 aircraft on exhibit. It expects to add 20 more by the end of this year, an inventory that will increase to nearly 200 after Phase II is completed.
Consistent with the policy of other Smithsonian Institution museums, Udvar-Hazy does not levy an admissions fee. However, a $12 fee is charged to park in its 2,000-vehicle lot. This fee, which is required by the museum's lease with the Washington Airports Task Force, will be applied to Phase II development.
The facility is named after aircraft leasing magnate Steven F. Udvar-Hazy, who donated $65 million for the project. It is expected to attract three to four million visitors a year. By mid-July, attendance had reached 1.2 million.