When Donna and William Whalen drove their blue 1973 Chevelle into the driveway of their home recently, out spilled three tired but tanned clubs, tennis bags, pillows, golf clubs, tennis racquets, T-shirts emblazoned with "Nags Head," two hermit crabs in a cage and lots of lots of sand.

The Whalens were returning from the ritual that families, be they neighbors of the Whalens in the 30-year-old subdivision of Mount Vernon Woods or residents in the newer, professional community of Waynewood, all say is a cornerstone of their summer - the traveling vacation.

A drive through these southern Fairfax County neighborhoods during the summer months reveals mothers like Penny Lane of Waynewood savoring an extra hour of sleep in the mornings, and fathers like William Walthall, a computer service salesman, building an addition on his home.

Children are spending their out-of-school days splashing in community pools like the one at the Pohick Bay Regional Park; playing in recreational programs like the one at Mount Vernon Woods Elementary School or attending day camps like the one run by United Wesley Methodist Church.

But a chat with families here, no matter what their income bracket soon revolves around the highlight of the summer. That is the one or two weeks when pets are farmed out to kennels or friends, newspaper deliveries stopped, neighbors asked to water plants, finishing lines ans cameras taken out, bags packed, the car or camper crammed and routine left behind.

That's why they say they go on vacations - to get away for a change.

Even when a daily routine is hard to discern, as in the Ungerleider household in Waynewood (a dozen children plus pets) a vacation serves to break the pattern. Arthur Ungerleider, father of 12 says. "Even though we have a non-routine here - that's the routing. It's important to have an opportunity to get away from where you are every day. It's no fun to cook a meal in the rain or to sleep 10 in a tent, but it's a change. And you get a chance to drop your dirty clothes in the middle of the tent instead of the middle of your room."

But there's another important reason why families say they go someplace together on vacation. It has to do with generations. Many parents say they want to give their children something that they never had while growing up.

"Vacation was walking to the Deleware River for a swim when I gre up," said Ungerleider, a computer accessary salesman who was raised in New Jersey. "And if you went to the beach it was because a rich relative had rented a bungalow and invited you."

"We didn't take vacations when I was a kid," said Nellie Pugh who was raised with her seven brothers and sisters on a West Virginia farm. "Sometimes mother would cook a meal at home and we would all pile into the truck and go on a picnic."

Nellie and George Pugh of Springfield take their three children with them on their trips. Otherwise, Mrs. Pugh thinks aloud, "When I'd get there, I'd say, 'Oh, I wish the kids could see this.' I wouldn't exactly feel guilty, but I guess you could say I'm enjoying life through them."

Many families say they set aside weekly or monthly sums all year long to have enough money for vacation. Donna and William Whalen, who both work in the Fairfax Couty school system, used to designated the money he earned as a coach for their vacation. "The soccer money was for vacation," Donna said.

Asked if there were any year he could not afford to take his family on a vacation, Ungerleider said, "Yes, all of them, but you either sacrifice or you play catch up afterwards.

In fact, many people say that the family vacation is so important that if their incomes were suddenly slashed in half, they would continue to set aside money for a vacation.

"So much money goes for bills, that if you can't enjoy it a little, it's not worthwhile making it," Donna Whalen said.

Once the money is saved, finding the right time to go is the next task. In families where both parents work and youths are involved in organized sports, not only must dad's vacation coincide with mother's, but parents say they must consider when the diving championships will be over and when the Little League season will end.

Before leaving home, families say they take precautionary measures against vandals. Most depend on neighborhoods to keep an eye on their home and to pick up their mail. Some alert the polcie to their absence so they can make spot-checks on their empty house. Some see that their lawns are mowed.

Nancy and William Dye whose home in the Mount Vernon Woods subdivision has already been broken into once, had planned to put their television in their neighbor's home and to lock their stereo in a closet when they went away. Nancy Dye's parents, who are on vacation in Colorado, have arranged for a "house-sitter."

Packing "usually leads to some pretty healthy arguments," said Ungerleider. "The kids come out with everything." How does he organize it? "Simple, it just stops as soon as no more will fit."

Vacation destinations depends on family imcome limitations but some of the places visited most often by families in these communities included Disney World, Nags Head, Chincoteague, Assateague Island, Myrtle Beach, Georgia, South Carolina and the Maryland shore.

The Ronald Taylor family vacations in White Lake, N.C. because "it's not real crowded and cluttered" and say they spend about $350 for a week in contrast to one of their relatives who recently parted with $80 in one night for two people in Virginia Beach.

Last week the Whalen family took what is a typical vacation for families in subdivisions like Mount Vernon Woods and nearby Fairfield where the median income is about $18,000. They rented a four-bedroom oceanside home at Nags Head, where rents range up to $400 a week for cottages on the North Carolina oceanfront.

During the week the cottage's occupants swelled to 12 spanning four generations when Mrs. Whalen's parents, grandmother, brothers and sisters joined the family. But it never seemed crowded, she said, because "we weren't in very much except for breakfast, supper and sleeping.

"We found out we didn't have to spend a lot of money - everything we did that was fun was free," Mrs. Whalen noted. The children, Kimberly, 11, William, 8 and James, 7, romped in the giant sand dunes climbing to "Jockeys Ridge" to watch hang gliders. They swam, fished and took a free ferry ride from Cape Hatteras to the island where the famous pirate "Blackbeard" was killed. The tennis racquets and golf clubs never got used.

"On the first day, you land in place and automatically have to make beds, buy food and then unpack it. The last day is the same in reverse. You unmake the beds, pack the food and clean the cottage. You're on your hands and knees as you back out the next renters - as a matter of pride," Lane said.

But the most popular kind of vacation in these middle-calss communities - both for the savings and the fun - appears to be camping, either in a tent or in the mobile campers that are so frequently seen parked in drive-ways.

The Pughs sometimes set up their tent right at Burke Lake in southern Fairfax County. "We like to rough it," Nellie said. "Oh listen to me, I do take along my foam rubber mattress," she adds with a laugh.

When the Ungerleiders go camping, it's in "the largest tent Seats Roebuck would sell." In past summers, they pitched it at Assateague or Cape Hatteras. And during winter school vacations, they usually have driven to Florida.

Almost anyonw will tell you vacations end too soon. But snapshots fill the family album and memories of vacations remain.

Often the most vividly recalled events that today brings smiles were far from funny at the time they happened.

Johnny Thurman, who with her husband Lee and five children is moving permanently this summer from southern Fairfax to Rehoboth Beach where they have vacationed for years, remembers one time they made the trip.

"Our twins were three weeks old. It was before the Twin Bridges were built. We spent five hours in a traffic jam. It rained the whole week. We spent it washing diapers and never saw the ocean once."

She is laughing.