From The New York Times:
The first thing visitors encounter in the main display area of the Udvar-Hazy Center, the National Air and Space Museum annex near Dulles airport in the Virginia countryside, is a huge black spy plane.

It's an SR-71A Blackbird, the ultimate hot-rod aircraft, one of 33 built at the Lockheed Skunk Works in California in the 1960s. This one last flew in 1990, traveling the 2,300 miles between Los Angeles and Washington in 1 hour, 4 minutes, 20 seconds — a transcontinental blur.

But now it's at a standstill, giving visitors the chance to appreciate its outrageousness. There are the two massive engines on short, stubby wings; the tiny cockpit where the two-man crew was shoehorned in, wearing bulky pressure suits; and the sweeping titanium fuselage that was built so loosely, to allow for expansion in the heat of supersonic flight, that the fuel tanks that made up the bulk of the plane routinely leaked, losing as much as 600 pounds of fuel taxiing to the runway.

The Steven F. Udvar-Hazy Center in Chantilly, Va., is about air and space, yes, but as the Blackbird shows, it's also about frozen time. More than 150 aircraft and spacecraft that in their day were among the swiftest or slowest, most graceful or ungainly, most useful or useless, sit on the floor and hang among the catwalks of this giant hangar of a museum as if plucked from the sky.

For Washington, D.C., visitors whose encounters with the Air and Space Museum have been limited to the original 1976 building some 30 miles away on the National Mall, the Udvar-Hazy Center, which opened in 2003 and is named for a major donor, an aviation industry executive, can be quite a different experience. There are fewer "name" aircraft like the Spirit of St. Louis to gawk at, no moon rocks to touch and, while as in the Mall building there can be hordes of schoolchildren, their noise tends to dissipate in this cavernous arched structure. Overall, with more than twice the exhibition space and about one-fifth the visitors, the Virginia museum has a quieter, more worshipful feel.

"There's no froufrou here," said Janet Baltas, one of the museum's nearly 200 volunteer docents, who can become so absorbed in describing the planes that their free tours often continue beyond the scheduled two hours.

The Udvar-Hazy Center is really about aircraft — and more aircraft. There are some of the earliest, including a replica of a Wright Flyer (the only nonoriginal plane in the place), and some of the latest, including the military's Joint Strike Fighter. There are small propeller-driven acrobats, commercial behemoths, carrier jets, pontoon planes, flying wings, helicopters and gliders. All the major World War II fighters are here, as are several German and Japanese warplanes of the same era, including the Aichi M6AI Seiran, which was intended to be carried inside a huge Japanese submarine but was never used in that way.

Visitors can gaze down into the glass-enclosed cockpit of one of the center's few celebrity aircraft, the Enola Gay, the mammoth B-29 that dropped the atomic bomb on Hiroshima; study a landing gear of an Airbus 330 that sits like a giant turkey leg on the exhibition floor; or examine the patched exterior of a Huey helicopter, testament to its service with the 229th Assault Helicopter Battalion in Vietnam. There's a Boeing 307 Clipper, the first pressurized passenger liner, its gleaming aluminum fuselage attached to wings and a tail section adapted from the B-17 Flying Fortress.

Over in the space gallery, the main attraction is the shuttle Enterprise, which was designed solely for flight testing in the atmosphere and will eventually be replaced by one of the spaceworthy shuttles when they are retired. The space gallery also holds some of the more unusual items. There are rocket engines with exquisitely tooled ductwork and bell-shaped nozzles and an old Univac 1232 computer, used by the Air Force to control satellites for more than two decades (and originally equipped with a paltry 120 kilobytes of memory).

The enormity of the collection can prove overwhelming, docents say, as can the vastness of the building (which has huge sliding doors to allow new additions in, towed or taxied up from the runways at Dulles).

Rodney L. Wright, a docent who is helping build a database of information about the museum, said that many visitors, most often men, spend hours wandering from airplane to airplane, like kids in a candy store. Family members who lack the patience or interest to keep up have been known to retreat to the museum's restaurant or gift shop, or down the road a couple of miles to the Sully Plantation, an antebellum historic site that makes a good change of pace.