BABY BEN, as Ben Loveland is known throughout the competitive boomerang world, has a ferocious right arm.He can fire a boomerang shaped like Admiral Nelson's hat outward more than 20 yards, and it comes whipping back to him mere feet from where he's standing. He can catch a balsa boomerang between his toes.

He'll be 4 in November.

In April 1982, when he was 29 months old, Baby Ben became Australia's youngest-ever boomerang champion--and probably the youngest champion of any sport anywhere in world. Competing against kids up to age 15, he scored highest in the throwing accuracy event, beating 50 rivals. The runner-up was a lad of 14.

Baby Ben is a commanding presence on the playing field, at 3-foot-3 and 38 pounds, with tousled blond hair and fierce blue eyes. He's also a tough interview.

Before he'll answer a question, he likes reporters to bribe him with toys--especially racing cars, which he calls "fasties," much as he calls boomerangs "boomies." Turning somersaults to amuse him also helps. But after the somersaults, the best you get is still some cryptic reply like, "My Nelson's Hat is peeling."

"Kookie-kookie, kookie-kookie," he volunteered the other day, as he tossed boomerangs around West Potomac Park with his grandfather, longtime Australian champion Bunny Read. They are apples of each other's eyes, and spend most of their waking hours following each other around.

Baby Ben crouched over a pile of boomerangs, chose one, stood up, aimed and fired. It whirled out over the grass, climbed, changed direction and returned. When it touched down, Baby Ben leaped and pounced. "Good throw, Ben," Read yelled. Baby Ben grinned.

"Throw it, Pa!" Ben shouted gleefully at Read. Taking up a brightly colored V-shaped number, Read obeyed, hurling it some 50 yards toward the trees. Baby Ben stood directly behind, mimicking windup, release and follow-through. "What a little sportsman," marveled Walter Baum, who had called off a nearby Frisbee game to come over and watch. "Look at the way he struts, like a javelin thrower collecting his javelin."

"He's a dedicated little fellow," said Read, 46, a former train engineer who now makes boomerangs for a living. "If he wants to do something, he'll stick with it till he gets it. I made him his first boomerang when he was born. As a toddler, he'd crawl around the house with it in his hand. He preferred it to his rattle. I used to take him out back to throw and hold him in me arms. He'd say, 'More, Pa! More, Pa!' He was 18 months old when he got his first boomerang to return."

Today and tomorrow at George Mason University in Fairfax County, Ben will be taking part in the U.S. Boomerang Association Championships, trying to repeat his winning feat in Australia. It's part of a barnstorming promotional tour dreamed up by local boomerang maven Benjamin Ruhe, and sponsored by the Lands' End mail-order house and the Seattle Museum of Flight.

The last boomerang thrower Ben's size to come this way was the feral child who tossed his lethal one in the Australian movie "Road Warriors." Baby Ben's visit to Washington promises to be much nicer. And the folks from "That's Incredible" will record it for posterity.

Ruhe, who befriended Baby Ben on a trip to Australia two years ago, has concocted a little vaudeville routine, and the two of them performed it the other day in the park.

"Who's the original Ben?" Ruhe cried.

"You!" Baby Ben replied.

"Who's the famous Ben?"

"Me!" came the answer, with a squeal of delight.

But when a film crew hired by Ruhe arrived, Baby Ben sulked for the camera, his frowning face the picture of misery. He hid behind grandpa's legs.

"Don't ever say we're exploiting him," Ruhe said. "He eats, sleeps and breathes boomerangs. He likes to throw them all day long. He even takes them with him to bed."

Baby Ben has been learning a lot lately about the the pleasures and pitfalls of fame. When he, his grandfather and his parents, Trevor and Leanne Loveland, jetted in from Down Under two weeks ago for the seven-city tour, they descended into a media maelstrom.

In California's Oakland-Alameda County Coliseum, before an A's-Yankees game, Baby Ben chucked his boomerang for a cheering crowd of 50,000 fans. He amazed hundreds at Seattle's Museum of Flight, and conducted teaching sessions in Oregon for scores of admiring kids. He visited Disneyland and the National Zoo, and fans have favored him with such goodies as stuffed animals, sheriff's badges and whistles.

A 9-year-old boy in Portland asked for his autograph. "I can't write," Baby Ben demurred.

"In Portland, there were four TV stations and one newspaper, one right after the other. In Seattle, there were three newspapers and two TV stations," said Leanne Loveland, a robust, woman of 21, and a competitive thrower herself.

"The 'That's Incredible' people wanted him up at 7 in the morning Saturday, so they could work him for four hours before the tournament. Well, we don't want to do it and that's that. He doesn't like the TV cameras. He's had so many stuck right in his face, I think he's just sick of it.

"He does like to throw boomerangs," she confirmed. "At home, he's always wingeing to go out for a throw. But we don't want to push him. He gets a little tired and cantankerous sometimes. He's just the typical 3-year-old."

From Washington, it's off to Wisconsin for another exhibition and finally, like a boomerang, home.