WHAT A FEELING!. . . . He flips over on his back going out of control. . . . Jesus, I gotta be hittin' him . . . Must be doin' a hundred and fifty . . . EEEeeerrruuunnnnn! . . ."

All you see is this skinny guy on the stage, wearing a World War I aviator's helmet and goggles, and another guy at the piano making machine-gun noises into his mike, and the skinny guy suddenly peels off, his hands banking, swerving, nosing over into a screaming dive. And you are right there with him, looking over the cowl of the cockpit as the muddy trenches of the Somme rush up at you . . .

It's a play. "Billy Bishop Goes to War," which has its U.S. premier at Arena Stage on Tuesday, is a sort of revue based on the true story of the Canadian ace who shot down 72 enemy planes in barely a year. The whole extravaganza -- with its songs and its 18 speaking parts -- is played by two Canadians, John Gray and Eric Peterson, both 33.

Next month the show moves to New York with a promising future in front of it. Mike Nichols and his co-producer, Lewis Allen, will be shepherding the play there. A year ago Nichols flew up to Listowel, a town of 5,000 in western Ontario, to catch "Billy." It was being put on in the Legion Hall and there was a blizzard, but Nichols got there in a rented car, driving over from the airport at Stratford.

At that, he was probably lucky to find the production. It has played from Vancouver to Halifax, from Saskatoon to Montreal -- a pocket triumphof Canadian theater.

"On one level, it's a success story, a little like 'Rocky,'" said Gray, who wrote the script and the songs. "Billy was one of those kids everybody knows in their hometown -- a wise guy, always in trouble, but smart."

Somehow Bishop, the lisping farm boy, came into contact with Lady St. Helier, a wealthy grande dame who had introduced Winston to Clementine, and she wangled a chance for him to join the Royal Flying Corps. In the stage version Billy, the dowager, the school chums, the Germans, King George V, British generals -- all are played by Peterson. He also does a Nieuport biplane.

"I'm not even sure it's 18 characters," Peterson mused. "Some of them are walk-ons, of course."

Their voices change, too. One night a general will sound rather like Alastair Sim; the next night he's pure Terry-Thomas. But you always know who is who, for each personage has a certain way of standing, a characteristic gesture or some other leitmotif.

They are taken from Peterson's own experience or from movies he has seen, but they are transformed into what they must have looked like to young Billy Bishop.

"The play is also a parable about colonialism," Gray said, "and also about the experience of war itself. The issues of that war were really blurred. It was the last throes of dying empires. The colonies were injecting vigor into the British war effort. . . ."

Gray and Peterson have been steeping themselves in World War I ever since they took to reading Bishop's autobiography a year ago because they were bored in Ottawa.("If you've ever been to Ottawa, you know what I mean," they said more or less in unison.) Both men had been devoted to the stage -- in one form or another -- for most of their adult lives. Gray as a playwright and song-writer, Peterson as an actor. At the time they began working on "Billy Bishop," they were involved in a joint production. They already had experimented with the multiple-character idea in a pleasant also-ran called "Herringbone," and Gray had made a name with his book and songs for a revue about truckers, "18 Wheels."

"Anyway, we had different concepts of what Billy must have been like," said Gray. "We started talking about him.The book was nothing but an account of his first 42 kills.You see, he was absolutely unknown in Canada when we discovered him. In his time, he was the most famous Canadian."

Canada in 1914 was the flyingest country in the world (still is, Peterson says), and long before the United States entered World War I, adventurous citizens were getting into the fight with various Canadian or French outfits, notably the Lafayettes Escadrille. William Faulkner was one, and James Norman Hall and other romantics.

"Those were the champagne-and-silk-scarf fliers," Gray muttered. "They were doing it for a lark."

By the war's end, the British Royal Flying Corps was one third Canadian, for much of the sketchy training was done in Canada. Many of the top 10 Allied aces were Canadians. There was an unwritten rule that any Canadian doughboy could get himself out of the trenches by volunteering for the RFC.

"They were very young. Nearly all of them were 18 to 23, when you still think you're immortal. They grew up fast. There were more killed in training than in the war," Gray said.

Billy Barker, another Canadian ace, was a better flier than Bishop, Peterson said. He would lure heavier planes behind him in a steep dive, then roll out and wind up on the enemy's tail. Bishop was such a hell-for-leather pilot that he once said he should have been a German ace too -- because he's wrecked so many British planes.

Still, even the worst of them had to be gifted pilots. Their planes cruised at 80 m.p.h. and stalled at 12 m.p.h. The German Fokkers were superior in almost every respect.

"Billy Bishop would hang up there in the sky like a hawk. He only went in if he had some advantage. He'd go after the last in line if there were more than one. And if a dogfight went on too long, he got out. There was no percentage."

They were obsessed with numbers, the aces of World War I. Numbers could make a man famous. Sometimes fliers would go out on their own time, working 16, 18 hours a day to score another kill.

"It wasn't men we were killing," Bishop said once, "but machines."

It got so the old hands around the airfields could tell the hunters from the hunted even before they went up: The hunters were the ones who checked the gas supply and the ammo. The hunted were the ones who checked their parachutes and made sure they had plenty of francs.

In that war, a pilot's combat life figured to last about 11 days.

Gray and Peterson have never fought in a war. Maybe that's why they were so fascinated by this other generation of young men. Much of their experience of military types comes from movies. They note that many British actors have played soldiers -- even Noel Coward, the song-and-dance man.

There's also a tradition of multiple roles in British film: Alec Guiness, Peter Sellers, Alastair Sim.

"When you see a war story, you always expect the author to be either for it or against it," remarked Gray. "We just try to describe it without judgment."

Billy Bishop liked to kill. It was easier in that mudless, pure, one-to-one sky duel. It was a machine, a number, that went spiraling down, and the doomed flier might even wave, as though he were immune to what was happening.

The remarkable thing about this wild little production, with its grown men making engine noises and running around the stage with a 5-inch wingspan plane, is that it can tell us this fact about Billy Bishop -- this fact about all of us -- so deftly that we hardly know it until after. And they do not judge. Who could?