Clowns, trained animals, barking concessionaires and nearly 2,000 spectators gathered under the Big Top at Frying Pan Park in Herndon last weekend, but not for a circus. The event was a rodeo.

For the Frying Pan Park Championship Rodeo, the Triple K Rodeo Company of Hagerstown, Md., brought 20 bucking broncos, 11 evil-looking Brahma bulls and 35 steers and calves into the cavernous indoor arena, and 96 cowboy contestants rode, roped and 'rassled in three sold-out performances. In all, almost 6,000 visitors paid $5 each to see the rodeo, sponsored by the Fairfax County Park Authority.

Country was the theme of the day, and at times it was difficult to tell the spectators from the participants. Blue jeans, western-style shirt and Stetson hat was the costume de rigueur for both men and women. Country music twanged over the tinny sound system, Sam Legard brought his "pit-cooked barbecue" from Lovettsville, Va., and paper platters of Pennsylvania Dutch "funnel cake" were on sale, along with tickets to an upcoming Tammy Wynette concert. One vendor did a brisk business in cowboy hats, at $14.95 to $70. The boot concession was not quite as busy--perhaps customers were discouraged by the prices, some of which approached $200.

Dave Case of Waldorf, Md., was on hand with his mechanical bull, giving would-be cowpokes an opportunity to taste what the real cowboys would be going through in the arena.

"It's never the bull that hurts you, it's the fall," Case said before the start of Sunday's show. "This mechanical one actually isn't much like a real bull. This one's a little more predictable."

Case's mechanical bull could not, for instance, turn and charge a roundup horse, which is just what the first bull did in Sunday's first event, sending up a loud "oooh" from the audience. That was to be the first of many chilling thrills in the 2 1/2-hour show. Cowboys were thrown from bucking horses and bulls and landed on the arena's dirt floor with muted thuds. But if there were any injuries in the rodeo, they were limited to the cowboys' pride--and their denim-clad backsides.

Contestants traveled from New Mexico, Pennsylvania, New Jersey and even Staten Island to compete in the two-day affair, and paid a $25 fee for each of the seven events they entered. The Triple K Rodeo Company contributed $1,400 to the kitty and the total from each event was divided among the top three finishers.

Purses averaged $250, but Kenny Van Pelt of Ohio was the day's big winner. He came away with $287.50 for winning the calf-roping contest and an additional $150 and a silver commemorative belt buckle for capturing the "all around" honors.

"I think everybody--or at least every man--at some time or other in his lifetime wanted to be a cowboy," said Ken Brown, 54, who heads Triple K. "A couple of years ago, if you went into a place and had a cowboy hat on, you almost had to whip somebody to get out of there. But today, everywhere you go you see cowboy hats. A man might be president of a bank and have a western hat and a pair of boots on right here in Virginia--it doesn't necessarily have to be out West. Western wear has made a big advance, and I think rodeos will, too."

At one end of the oval arena, chutes launched bolting broncos and bulls under intrepid cowboys who struggled to stay mounted for a few seconds. Staying aboard a bucking horse or bull is tough enough, but the judges also rated form and style. Use of the wrong hand or improper positioning of the legs could get the rider disqualified.

Brown pointed out that rodeo is an original American sport, with practical roots rising from ranch life in the West of the 1800s.

"A few of these events aren't ranch events," he said. "For example, steer wrestling--that's not something you would do on a ranch. But take team roping: If you've got a pasture full of cattle but no pens to catch them, then a rancher has to rope them by the head and heels and stretch them out to doctor them."

Other rodeo events included bareback and saddle-bronc riding, calf-roping and ladies' barrel racing.

Frying Pan Park manager Lowell Pirnie said last week's success may mean a return engagement for the rodeo, perhaps as early as this fall.

"We're just trying to test a few things to see how well they go," Pirnie said, referring to the variety of attractions offered in the Frying Pan arena since it was opened a little more than a year ago. "So far, everything we have done has really been received well and we're pleased. . . . We didn't know how the response to the rodeo would be, but it doesn't surprise me that we sold out three shows."

The park authority expects to make about $8,000 from the rodeo, according to James A. Heberlein, park authority assistant director for operations. Pirnie said the decision on whether to have another one will be made "after we've had a chance to sit down and see how this one came out."

"I would come again next year," said Barbara Charlet, who brought her son Jamie from Annandale to see the rodeo. "This was the first time we'd ever been to a rodeo . We enjoyed it."

"I've seen two other rodeos out West and they were a little better, but for a Virginia rodeo this one was all right," said Rick Keller, an accountant from Herndon who brought his wife and two small children.

One spectator at Sunday's rodeo was Joseph P. Downs, park authority director, who came with his family. Clad in jeans and western shirt, Downs was all smiles as he stood in line for a platter of funnel cake. Pondering the question of future rodeos, Downs looked at the crowd around him and said, "I don't think we can stop it at this point. We had to turn away quite a few people at the door yesterday and today. . . . I'd like to do this again; I think it fulfills a need in this area. You don't have too many rodeos in Fairfax County."