It's in the nature of experiments that not all of them succeed. One that rather fizzles is the Smithsonian Institution's new Experimental Gallery, whose first three exhibitions go on view Friday. It opens with a whimper rather than a bang.

It's true its contents are unusual. Even old Smithsonian hands accustomed to variety -- to Titians and Tiepolos, the biggest of stuffed elephants and Archie Bunker's chair -- are likely to be startled by the subjects of these shows. The first one presents portrayals of San Franciscans who have AIDS. The second helps explain why airplanes stay aloft. The third takes as its subjects the little hand-built clubhouses constructed in New York by that city's Puerto Ricans. This is, one must admit, not the standard fare of the museums on the Mall.

But surprising us with content is not the mission of the gallery. "The subject matter itself is not the experiment," insists its director, Kimberly Camp. Instead, she is concerned with audience interaction, with displays that ask the visitor to listen or press buttons, and with farthest reaches of museum design. But it is precisely there that these three shows go limp.

The limpest is "Casitas: An Urban Cultural Alternative," the Puerto Rican-New York show arranged by Betti-Sue Hertz of the Bronx Council on the Arts. The casitas (little houses) that this show applauds are little painted shacks wrapped around with gardens. Puerto Rican immigrants have constructed them informally on many vacant lots in the most impoverished stretches of the South Bronx and East Harlem. Out there in the real world -- filled with laughing neighbors, perfumed by the smells of roast pork and fresh flowers, and enlivened by the sounds of the plena and the salsa -- the neighborhood casita may be a place of real joy. But the one that's been constructed in the Arts and Industries Building has no life within it. It's as if it's been canned. Nothing's growing in the garden, nothing's cooking on the stove, and its various Puerto Rican props -- those decal maps of the island, those photographs of Hector "Macho" Camacho and Roberto Clemente, and that plaster bust of JFK -- feel both sad and dead. "Visitors," we're told, "will be able to walk through the casita and touch {these} adornments." But who would want to?

The casita itself is surrounded by text panels that celebrate casitas, the people who use them and the Bronx Council on the Arts. If you're looking for a state-of-the-art museum display, look elsewhere. The panels' photos are not much and the wordiness is killing. Most of this show feels like a magazine article pasted to the walls.

The AIDS exhibit, "Project Face to Face," organized by Jason Dilley, is simpler and more touching. Dilley took plaster life-casts of the faces of 20 people with AIDS. He also recorded their voices so that the visitor, who dons earphones and presses a button, can hear Sergio Mayorgo saying, "I was using drugs. ... I was scared to tell my wife I was positive. ... I was real mad at myself for having the sickness," while staring at Mayorgo's plaster face. Dilley hopes that by thus "meeting" people living with AIDS, the public might replace its "negative attitudes" with more "positive reactions." That's not altogether likely. Those casts, set on black velvet, have a corpselike pallor. Their eyes are closed as if in pain. Something in their presence insists upon death.

"Principles of Flight," the little participatory show organized by Beatrice Matkovic of the National Air and Space Museum, is livelier by far. What holds that blue ball floating in midair? Poke at it and see. How do you make palpable the 14.7 pounds of air pressure pressing on each square inch of your skin? By hefting the 14.7-pound bowling ball Matkovic has provided, that's how. Her exhibits move. They also surprise. Why is that flat plastic plate sucked into that blast of air when "common sense" tells you it should be blown away?

Washingtonians have been spoiled. Few museums elsewhere can begin to meet the high installation standards set by those that line the Mall. If you can look beyond their rather fashionable subjects, if you can see them, instead, as experiments in museum display, you'll see that the overly wordy casitas show, and the AIDS show too, look stiff and amateurish. We're used to better. The main reason that Matkovic's aerodynamics show works as well as it does in Washington is that we do not yet have anything resembling a participatory science museum.

The Experimental Gallery -- which has thus far received more than $1.2 million from the Cafritz and Rockefeller foundations, the Pew Charitable Trusts and the Smithsonian's Special Exhibitions Fund -- has been given 7,000 square feet of nicely flexible exhibition space, a worthy, open mandate, and ample freedom too. Eventually it may revolutionize the Smithsonian's exhibitions. But it hasn't done so yet. It isn't even close.