The new acting director of the National Air and Space Museum, Donald S. Lopez, told staffers yesterday that the popular institution will continue to "charge ahead" in the ways established by Director Donald D. Engen, who died Tuesday in a Nevada glider accident.

More than 100 staffers gathered in a third-floor conference room at the museum on the Mall also heard Smithsonian Secretary Michael Heyman affirm that "we'll carry on, and carry on his dream."

Engen, 75, a retired admiral and war hero, was known as a graceful, considerate boss who pulled Air and Space out of a downward attendance spiral in the wake of the 1994 controversy over the exhibition about the Enola Gay, the plane that dropped the first atomic bomb on Japan.

The session was closed to the press, but Lopez--himself a World War II combat ace who has served at the museum for 27 years--later reported the remarks, adding that he was willing, if necessary, to remain acting director until 2003, when a vast new branch of the museum is slated to open at Dulles Airport.

The annex--where more than 280 airplanes and spacecraft, including the Enola Gay and a space shuttle, will be displayed on a 176-acre campus--was a key element of Engen's dream, Lopez and others said yesterday. The director was spending a good deal of time raising money for the Smithsonian facility from the corporate, aviation and military communities.

In his remarks to the staff yesterday, Heyman told everyone to press on to "get the Dulles center opened," Lopez reported. Lopez had commiserated with staffers during the session, assuring them: "We're not going to make any changes. Keep charging ahead."

The new director's responsibilities will be far greater than shepherding the new Dulles center, however. The whole tone, tint and spirit of the museum had been thoroughly revamped by Engen after his appointment three years ago last month.

When he came on board, veterans and military groups felt they were reclaiming a beloved institution from "academics" such as former director Martin Harwit, who, they believed, had tried to distort a display about the Enola Gay.

In what turned into a big, nasty spat, the military and veterans groups prevailed in their view that the exhibit should emphasize American military heroism, rather than be a scholarly look at the beginnings of the nuclear era with Japanese sensitivities taken into account. Veterans argued that the 1995 exhibit should focus on the bomb's role in ending World War II, rather than its role in starting the Cold War, as the exhibit was originally conceived.

"We had grandmothers calling up in tears" because they felt the proposed exhibit misinterpreted history, recalled Mike Fetters, a former spokesman for the museum. "Then Engen comes on board like he was from Central Casting--war hero, former head of the Federal Aviation Administration, he built Piper Aircraft. He was the right guy at the right time."

Engen, a World War II dive bomber pilot who sank a Japanese cruiser, was awarded the Navy Cross for extraordinary heroism. He instinctively understood Air and Space the way most Americans do, Fetters said--as a patriotic Temple of Technology.

Lopez recalled yesterday that Engen would arrive at work at 7:15 a.m., strolling through the exhibits to make sure there was no dust on the aircraft. "He understood the museum was for the people, and he wanted to make it as friendly and open a place for the public as he could."

Most important from a political--and fund-raising--point of view, Fetters said, "he brought instant credibility with groups across the spectrum--sports, military, business, veterans groups."

And children. "He had school kids do murals" that were displayed in the museum, Lopez said. And, Fetters added, he ramrodded a total make-over of the museum's major space hall "so that it told a story rather than just being a collection of technology." Hands-on exhibits were created where children could get inside a cockpit and work the controls.

Fetters and others also recalled yesterday that the former vice admiral--"with his usual grace, he was one of the most un-authoritarian military men I've ever met," Heyman recalled--had reorganized and streamlined museum management, improved morale and rolled out a series of popular new exhibits.

Chief among these was "Star Wars: The Magic of Myth," a study of the popular movie from a cultural standpoint, which with a million visitors a year became the most visited exhibit in the world's most visited museum.

As a result of Engen's initiatives, Fetters and others said, attendance increased from 7 million annually at the time of his appointment to 10 million last year.

"Don has been a wonderful director," Heyman said in a statement issued yesterday at the time he appointed Lopez as acting director. "He will be sorely missed at the Smithsonian."

Heyman said it is not clear what role he will play in the appointment of Engen's permanent successor, since he himself is leaving his job at the end of the year. A search is on for Heyman's successor, and the result is expected to be announced by the Smithsonian's Board of Regents on Sept. 13.

Heyman normally would hold off making a lame-duck appointment out of courtesy to his successor. But if he can privately learn who his own successor is to be and work with him or her, a new Air and Space director might be appointed quickly, he said.

"It would be very helpful, in terms of administration and the capital campaign [for the Dulles expansion], to act more rapidly," Heyman said.

If he could play a role in the search, he added, "I'd be looking for somebody who had a lot of those qualities" that Engen had. "He was a doer, but a doer who was smart and effective. He was a genuine hero, too, and there is something to be said for having somebody with those claims and credentials in his repertoire as the chief of Air and Space."

Sen. John Warner (R-Va.) helped choose Engen for the museum post and had been working closely with him on the Dulles expansion. "He set course and speed for that museum," Warner said yesterday, "and we'll be able to find somebody to carry on" in the same direction.

Lopez agreed. "They could move fast," he said, "but they have to get somebody acceptable to the air and space community, because they're the ones who we want to make the donations.

"It should be one of theirs, one of their own."

CAPTION: Former Air and Space Museum director Donald D. Engen envisioned a vast expansion of the museum.

CAPTION: Donald S. Lopez, the new acting director of the popular Air and Space Museum.