DAYTON, Ohio — When the National Museum of the U.S. Air Force began looking at ways to depict the wars in Iraq and Afghanistan, big obstacles loomed.

Certain missions remain classified and some equipment — such as night-vision goggles — was unavailable for display, because it was still being used by troops or might be if they are redeployed.

“We don’t want to take things away from the warfighter,” said Jeff Duford, a museum historian. “It was pretty challenging.”

The museum’s struggle underscores the difficulty facing other institutions trying to depict the wars while the conflicts are still underway.

The Air Force museum decided to focus an exhibit opening Tuesday on the experiences of the wars’ airmen. It features more than 400 artifacts, 18 fully equipped soldier mannequins, a robot demonstrating how it inspects roadside bombs and a Sikorsky special operations helicopter used to covertly enter enemy territory.

Since the history of the wars has yet to be fully written, the museum honed in on the individual Americans fighting the wars, using artifacts to tell their stories, Duford said.

“The way that people act — the heroism and sacrifice that people have — that really transcends time,” he said.

Other museums have faced similar constraints.

The Wisconsin Veterans Museum in Madison plans to open an exhibit this spring portraying the role of Wisconsin soldiers in Iraq and Afghanistan. Museum officials interviewed soldiers and collected uniforms, helmets, boots and other items.

But Jeff Kollath, curator of programs and exhibitions, said the Pentagon has become more restrictive about what soldiers can bring home since the Vietnam War, making it more difficult to obtain artifacts that tell important individual stories.

Kollath also said many soldiers who served in Iraq and Afghanistan are in the National Guard and Reserve and return to their civilian lives after deployment, leaving many stories untold.

“They’re not spending a lot of time thinking about their place in history,” he said.

In 2006, the National Museum of the Marine Corps in Triangle, Va., opened a temporary exhibit that included photographs and artifacts from the wars in Iraq and Afghanistan. Spokeswoman Gwenn Adams said it took a little longer to catalog the artifacts and prepare them for display because of the ongoing nature of the wars.

“And keeping it current,” she said. “The challenge is to keep those photographs updated.”

Tim Clarke, spokesman for the National Museum of Health and Medicine in Washington, D.C., said the museum had to avoid interfering with military operations while collecting artifacts on military medical care in Iraq.

Last month, the museum opened an exhibit depicting a former Air Force tent hospital in Balad, Iraq. The museum stepped in after learning that the hospital’s emergency room and trauma bay, where the most seriously wounded soldiers were taken, were to be demolished. Artifacts from the hospital were shipped to the museum in April.

Museum spokesman Tim Clarke said museum officials took the time to learn all they could about the wounded soldiers who are depicted.

Duford, of the Air Force museum, said his institution benefited from the generosity of the depicted airmen, who donated their artifacts to the museum unconditionally and permanently.

Among them is Ramon Colon-Lopez, who took part in search-and-rescue missions in Afghanistan and provided security to Afghan President Hamid Karzai.

Colon-Lopez, 37, donated a blanket he used to blend in with the Afghan population as well as a pink and purple stuffed Cheshire cat he took on his missions as a good luck charm.

“I thought about it for awhile. But looking at preserving the history of what we’ve done, there couldn’t be a better place,” he said. “As far as the declassified aspect of things, I think it does a great job of depicting what we have done so far. We’re not done.”