Never mind the jumbo jets swooping low over this corner of McLean every five minutes: Turkey Run Farm is the kind of place where visitors expect Fess Parker to stroll out of the dense woods with a bear carcass slung over his shoulder.

"It's actually pretty neat out here," said Lamonte Washington, 10, as he surveyed the 100-acre preserve and its re-creation of an 18th-century homestead. "I wouldn't want to live back then. There was no Ataris, TVs and no telephones, you know."

Lamonte, a tricorn hat on his head and Nikes on his feet, was one of 40 Arlington fifth-graders who camped overnight last week at this park that was nearly closed by a federal budget cut last year. But since it was saved by a determined band of history-lovers, Turkey Run Farm -- officially, the Claude Moore Colonial Farm at Turkey Run -- has become one of the hottest educational resources in the Washington area and beyond.

"There's nothing like it on the East Coast," boasts Carol Deakin, the historian of the group that raised $500,000 to keep the park open.

When the National Park Service scheduled the farm for closing in February 1981, Northern Virginia residents enlisted the help of their congressmen to buy enough time for fund raising to keep the park open. They succeeded: In two months, the farm's friends raised $250,000 to match the grant of Claude Moore, a Loudoun County philanthropist who turned 90 last week.

"The response we got from the public surprised everyone around here. The people really did care, especially about the things that could educate their kids," said Deakin, who lives in Reston. "The help came out of the woodwork."

It still does. Employes of the Central Intelligence Agency in nearby Langley spend lunch hours repairing the farm's decrepit plumbing and electrical wiring. Some park service employes quit their civil service jobs to volunteer on the farm, which has a 25-year lease with the U.S. government for the property.

"We were also very pleasantly surprised by our collection at the gate," said Joe Harsh, a farm trustee and chairman of George Mason University's history department. The nominal fee -- $1 for adults, 50 cents for children -- for farm visitors has generated as much as $2,000 a month this year. The farm, with a $65,000 annual budget, has two full-time and several part-time employes.

"Our crew has shown us they can operate on a shoestring," said Harsh. "A lot of our volunteers could be making tremendous money, but they stay on at the farm."

Headquarters of the farm, located off Rte. 193 (Old Georgetown Pike) between Dolley Madison Highway and the Beltway, is two leaky government trailers that serve both as staff offices and research library -- the focus, appropriately, is on colonial agriculture. But the farm's real draw continues to be its overnight camping trips, a kind of "living history" program that has earned rave reviews.

"This is the kind of fringe program -- an extra -- that you always hear about the private schools pulling on," said Judie Leibner, the teacher who led a contingent of fifth-graders from Nottingham and Long Branch elementary schools last week. "It's tremendous that we have this kind of resource right here in our back yard."

Under wispy October clouds, her students, who included some of Vietnamese and Mexican national origin plus a number of learning-disabled and gifted children, dipped candles, wore rustic clothing they made themselves, foraged for wood, and ate chicken, soup, cornbread, cheese and cider out of wooden bowls and tin mugs. They played colonial-era games, then toured the farm, its primitive tobacco field, the one-room house, the vegetable garden and the livestock pens. At night, they slept on hay and blankets in flimsy muslin tents.

One of the few intrusions of the 20th century occurred when they were videotaped for a local school program.

"It was pretty good before the Revolution," said Long Branch student Kevin Gilpin, 9. "But your parents had to be really hard workers just so you could eat every day."

"The kids who use the farm will tell you they don't like to study history and that they aren't while they are here," said Deakin. "But they are learning history. They just don't realize it."

Harsh called the student program in the farm's Environmental Learning Center the farm's "best and most enduring aspect."

"You can't beat the kind of hands-on experience the kids have," he said. "For two nights and three days, they're living a program that is tied to the classroom." All teachers take an intensive, farm-run training course.

While it faces no shutdown now, Turkey Run will host several fund-raisers when it reopens next April following its winter closing on Dec. 1. "Compared to a year ago, we're in great shape," Deakin said. "Now we don't face the continual threat of being closed. And that's pretty nice."