Cannon Falls, MN--In his daydreams, Jim Theis sees small personal aircraft that can dip, turn, and hover like dragonflies. He envisions teen-agers soaring across town, dropping in on friends. And he foresees the day when soldiers will fly bird-like aircraft across enemy lines, swooping in on their targets as they do their reconnaissance.

Theis knows that his vision won't take shape soon. But he can't help working on it. Surrounded by fluid dynamics textbooks and reams of spreadsheets that contain 4,000 rows of propulsion calculations, Theis continues investigating his dream: the creation of a flapping-wing aircraft.

He's been at it for more than 20 years now. In the more than two intervening decades, he has taken time off to start his own company, New Product Design Inc., which he runs with his brother, Charley, who is the company president. Working in a converted barn in the tiny town of Cannon Falls (population 3,232), he has churned out ideas ranging from the theoretically esoteric to the purely practical. In all, he has more than 20 patents and countless unpatented inventions. Many of those involve turbines, stemming from work he did for the Hollymatic Corp. in the 1970s and Air Turbine Technology in the '80s.

But the flapping-wing concept is still the one that stirs Theis' inventive passions. He knows that its chances of near-term commercial success are slim, but that doesn't stop him. "Don't think I don't know what it sounds like when I talk about flapping-wing aircraft," Theis says."People think it's a waste of time. But I would ask you to think about what it would be like if we could use aircraft locally. I can foresee a time in the future when people will climb into their 'flappers,' punch a button, and a pair of wings will pop out."

That Theis can work on such experimental concepts is amazing in itself. Nineteen years ago, while flying an ultralight of his own design, Theis's aircraft clipped the edge of a steel tower and crashed 35 ft to the ground, breaking his back. He's still in a wheelchair.

In typical Theis fashion, however, his spirit was unbroken. His physical confinement gave him the opportunity to design better wheelchairs. In the past decade, he has designed steerable wheelchairs, hand-crank wheelchairs, and wheelchairs that fold up. His hand-crank chair is currently licensed to Ultimate Support Systems (Fort Collins, CO). The chair's hand crank is said to help eliminate serious hand, shoulder, and elbow injuries that often plague those in wheelchairs.

Whether or not the flapping wing enjoys similar commercial success isn't an issue for Theis. "You have to have faith in the process," he says. And because he has a rare abundance of faith, he continues his work, which is sponsored mostly by his wife, Linda. He has already laid out the design of a 420--lb piloted prototype with a 45-ft wingspan and a 15 hp motor. He plans plans to fly the prototype before the year 2000.

This year, he will again give a forum presentation at the world-renowned Experimental Aircraft Association Fly-In Convention in Oshkosh, WI, in August. The forum, he says, may not lead to the near-term development of a product, but it will add to the foundation of knowledge that's being built."The Wright brothers did all their work because they were driven by curiosity," Theis concludes. "When you invent, the passion has to be there. You can't pay for that kind of emotion."