AS AVIATION grew up it left behind a certain number of enthusiasts who never were able to transfer their allegiance from the wire-and-fabric kites of the early days to the closed-cockpit behemoths that took half the fun out of flying.

The original airplanes were built to human scale, and they had enough wings to make it possible to believe that they would fly. When they fell down, sometimes you could walk away.

That passion for the wind in the wires has been passed down from the pioneers to their sons and grandsons, a couple of dozen of whom spend every fair Sunday from May through October buzzing above the Virginia countryside near Warrenton to keep alive the barnstorming tradition.

The Flying Circus Aerodrome is not fancy and its pilots are not daredevils. "We don't do a thrill show, because none of us is interested in collecting insurance, said Ron SHelly last week as he tuned his Stearman stunt biplane for Sunday's season opener.

"Most of us are either airline or military pilots who work at flying and who come out here to get back some of the fun. The difference between these old machines and an airliner is the difference between riding a motorcycle and driving a streetcar."

This will be the eighth season for the circus, which was conceived as a way to get rich, but turned out to be "just a way to slow down the slide to the poorhouse," Shelly said. "It never has paid for itself and probably never will, but there are certain economies in pooling your losses. I lose money giving 10-minute rides for $15, but not as much as when I fly with the passenger seat empty. And a lot of us were surprised to find out we like showing off for an audience."

Showtime - weather permitting, of course - is 2:30, but people are encouraged to come early and stay late. "The gate opens at 10 a.m. [admission is $4 for adults, $2 for children 3 to 12] and there's usually something in the air. Most of our patrons are families who bring a picnic lunch and spend the day."

The Flying Circus always gives rain checks and often hands out free passes if mechanical problems cause the show to be cut short. The aircraft were delicate when they were new, and since most of them are now considerably older than their pilots, they spend a good deal of time spread out on the hanger floor. A Stearman that crashed after a mid-air collision last year is slowly being reassembled in one corner; stripped of its fabric and its shattered wings, it looks like a turkey three days after Thanksgiving.

On any given Sunday about a third of the crowd are repeaters, which speaks well for a routine - "The Greatest Show Off Earth!" - that is deliverately kept low-key and moderately cornball. Baron Von Anger, swaggering through the crowd in a German Imperial Army spiked helmet, is eminently hissable and always gets his just desserts; Father John Frizzel Jr. tosses out a roll of paper towels and as it streams toward the ground chops it to ribbons with the prop of his tight-turning Tiger Moth; the plane that's supposed to snatch Miss Fifi (Cindy Kuhn) aloft from midfield tailhooks only her tearaway flight suit, leaving behind a little bit of bikini and a lot of Ms. Kuhn. There is skydiving and wingwalking and, on calm days, hot-air ballooning.

At the end of the show the aircraft are lined up for inspection, each with a nervous owner praying somebody won't poke a hole through the fabric. "Do not touch the airplanes, please," announcer Ron David says sternly. Pause. "You may, however, fondle the pilots."

"We think - and hope - that the atmosphere here is very like it was in the early days," Shelly said. "Flying has become increasingly formalized and technical since World War II. From the time you climb into the cockpit until you taxi to the parking strip some guy on the ground is telling you exactly what to do every minute. This gives us a chance to experience something of what seat-of-the-pants aviation was like.

"The audiences seem to appreciate it. I think a lot of them would come out even if there were no show, just to look at the planes. I never get tired of taking people up, because I can watch the passenber's face in the front-view mirror and share a little of that first-time excitement again."

Shelly pays particular attention to the color of a passenger's face, because he is always downwind. He alters his routine to suit the subject, jazzing it up a little for a 10-year-old girl who's having the time of her life but backing off slightly to save the self-respect of her father, who is game but somewhat green around the gills.

"I flew for years in the Navy and never knew what flying was," Shelly said. "You fly in cocoons now. Think about the astronauts on the moon, all bundled up in those incredible suits: They never touched it. Man, in these planes you can see and hear and taste and feel flying."

It seems a lovely way to go broke.