Fred Klein has a nutty dream. Someday he and his partners in the foot-launched ultra-light aviation society will put together a cross-country whistlestop tour that will put the barnstormers of the '20s to shame.

He can see it now. "We'll follow the interstates. When we get low on gas we'll just zoom into a service area and fuel up. When we hit the towns the people will go wild."

One problem. "We haven't figured out yet how to take people for rides." And what's an air show without rides?

Actually, the death-defying foot-launchers aren't really sure they can take themselves for rides. Witness Klein's performance a couple of weeks ago as he warmed up his one-man motor-kite for an appearance in the Flying Circus in Bealeton, Va.

First flight, not bad. Of course it was so early no one was around to see it, but Klein insists it went off without a hitch.

"You probably saw my plane up there when you were driving in. I'm the only one without a body. Or a mind."

Second flight, disaster. Klein strapped himself into his fragile wings and hop-scotched across the grass field all right, and even got airborne with a last few leaps. But somewhere along the way he hit bad air. It was up and down, as they say, as he frantically circled the field looking for lift.

With the little chainsaw motor screming along at 7,500 rpm he found downdraft, instead, in the propwash of an ancient biplane coming in for a landing. Clunk, then crash, nose-first into a bumpy hillock.

Klein gathered himself up with a sigh and a stream of low-key epithets that would make a linebacker blush. He hoisted the little plane to hip-level and trudged back to his takeoff area.

A little scotch tape patched up the holes he'd torn in the rip-stop nylon wings; a couple of blasts with the three-pound sledge straightened the frame. A half-hour later Klein was aloft again, this time on a magnificent 15-minute tear around the little field, bobbing and bouncing with the drafts. He spotted a cameraman below and descended to a perfect five-step landing, practically in the bewildered photographer's lap.

Two more flights and Klein was done for the day. His final nose-bending touchdown left him hobbling off on a twisted ankle.

Who is this Fred Klein and why is he trying to kill himself? "The whole bag is getting back to sport flying. It's very simple.

We don't have to fool with airports; there are no encumbrances," said the Washington architect.

"We're trying to reinvent the airplane, to fly without the infrastructure of presentday aviation."

The Federal Aviation Administration gave Klein and the other foot-launchers a break last May when it redesignated the wacky one-man craft so they needed no registration and pilots needed no licenses. Klein, who has never flown real planes or the hang-gliders that his foot-launched aircraft evolved from, can now take off and land wherever and whenever he chooses.

All he has to do is find some soft ground. He tried asphalt once last summer and learned his lesson about hard, flat surfaces.

Klein's craft is constructed from a kit. It's an Easy Riser fixed-wing hang glider, and he ran it off some small hills without a motor for awhile until he got the feel of it.

Then came the chain saw motor and prop, also from a kit, and the tacked-on altimeter, wind-speed indicator, mouth-operated cut-off switch and other 'accouterments' of powered flight. His initial plan was to use the motor to get to soaring height, then cut it off and glide in the quiet peace of altitude until the sky ran out. But he admits, frankly, he's not had the guts so far to cut the buzz saw off.

If you're driving down the Jersey Turnpike next summer and you hear a chain saw sweeping by overhead, pull in to the next service area and wait awhile. Pretty soon Klein will be along. Just as soon as he gets the kill switch out of his mouth and the plugs out of his ears he'll have a tale to tell you.