Donald Hoover, 14, is a three-year veteran of the "Gravity Grand Prix," having raced in his first All-American Soap Box Derby as a Junior driver on the Mount Trashmore track in Norfolk, Va., in 1982.

"I placed third in that race," he says, adding that this year he is competing in the Washington regional for the first time . . . and expects to win.

But this time, Donald is faced with friendly sibling rivalry: Brother Douglas, 13, and sister Denise, 11, also plan on winning in the Senior division competition. And his brother Dustin, 9, has high hopes for his car in the Junior division.

The Hoovers, of Fort Belvoir, will be among at least 40 youngsters competing here in the two divisions for the chance to go nose-to-nose with approximately 180 other finalists -- from Canada, Germany, Guam, the Philippines and Venezuela as well as several other American cities -- at the 48th Soap Box Derby finals in Akron, Ohio, Aug. 10.

Denise made it to Akron (where she placed 16th) last year, having won first place in the Junior competition in Norfolk. Douglas, who placed third in that division in 1983, came in second in Norfolk last year, losing to his sister by just a few feet.

The Hoovers believe they are a family to be contended with. All are building their cars from scratch this year, and, though three of them are competing in the Senior division, they're helping one another as they go through the long, demanding construction process.

Their parents also are playing an active role. "I'm the go-fer," says their mother, Diane. "I go for this and that and I run interference with their father when they want to take a break and he is pushing for them to go on."

Diane Hoover says her husband Don "is with them every minute . . . teaching them how to use the tools, getting them to work together."

That, say adults connected with the Soap Box Derby, is one of the aims of the program. The derby's goals, in fact, "have not changed since it began in 1934. They are to teach youngsters some of the basic skills of workmanship, the spirit of competition and the perseverance to continue a project once it has begun."

Washington has been a big derby town in the past. Last year, however, the future of the derby here was in serious doubt. Only a handful of youngsters entered the competition, and the Downtown Jaycees -- major backers of the event -- said last July they were considering withdrawing their support.

The local competition got its reprieve later last year when the Automotive Trade Association National Capital Area (ATANCA) agreed to provide a much-needed publicity blitz as well as a $2,500 grant to match a like amount provided by the Jaycees. "We think the program is back on the upswing," says Chuck McElroy, president of the downtown group, "thanks to the great support of ATANCA and its president, Gerry Murphy." Murphy says ATANCA is committed to "bring the Soap Box Derby back in a big way for Washingtonians."

Derby officials say the cost of running a local derby program runs around $2,000 for such things as T-shirts, racing helmets, trophies, prizes, police security, insurance and newsletters. Added to those costs are sponsorship of needy youngsters and their cars, shipping the winning racers to the Akron finals and transportation of the local finalists to the All-American.

McElroy stresses the need for individuals, businesses and charitable organizations to volunteer their financial and moral support. The Hoovers, for example, have found a sponsor for only one of their four entries, and a number of other local youngsters still are in need of financial assistance.

While derby officials play up the satisfaction that comes in the construction of the cars, the participants say guiding their cars down the 953.75-foot tracks -- at speeds up to 32 miles per hour -- provides the biggest thrill.

The rewards for local and national winners have an appeal of their own: The local first- and second-place Seniors receive trophies and $250 and $150 savings bonds; Juniors get trophies and $150 and $100 bonds. The top three Seniors in Akron receive trophies and scholarships of $5,000, $3,000 and $2,000. The top three Juniors win trophies and power tools. Each local champion receives -- among other gifts -- an official derby watch, racing apparel.

Win or lose, Fort Belvoir's four D's -- Donald, Douglas, Denise and Dustin Hoover -- say they're looking forward to the competitions.

"We hope we win," says Diane Hoover, "but we're really taking the attitude that this is a stepping stone in Washington. Watch out for next year if we don't place this year!"