Tests Ideas on Computer Model : Ultralight Pilot Flying in Face of Reality

Flying more than 600 miles in an open-cockpit aircraft originally designed as a hang-glider might sound like a thrill-seeker’s stunt, but Tom Pratt considers himself anything but a daredevil.

Pratt, an aeronautics engineer, holds two of the three world records for microlight, or ultralight aircraft, which aviation buffs call Type R aircraft.

In a plane that weighs less empty than many men, Pratt has flown farther in a straight line than anyone else--693.3 miles. He also owns the distance record of 500.5 miles over a closed course in his 275-pound Mitchell Wing A-10.

Sometime in the next year, Pratt said, he wants to capture the only Type R record he does not hold: that of altitude. He said he will modify his tiny plane so that it can be flown at 19,600 feet.

Admittedly, Pratt said, the climb will approach performance limits--of his own body, not the plane.

“The airplane can go a whole lot further. I don’t know if I can,” said Pratt, who spent 11 1/2 hours in the sidecar-sized cockpit when he set the open-course distance record. “I get buffeted around up there pretty good. I’m pretty wiped out after a long flight.”

Pratt helps design aircraft brake assemblies for the Parker Hannifin’s Aircraft Wheel and Brake Division in Cleveland. He uses a computer model of his airplane to explore its capabilities.

“I’m sure I know a lot more about the specifications of that airplane than the factory does,” Pratt said. “Once you build a computer model, there’s a lot you can do in terms of playing around with the performance.”

Pratt, 33 and father of three, said he didn’t want to leave anything to chance, so he spent 500 hours planning the 11 1/2-hour flight from Winterset, Iowa, to Cleveland. By the time he had strapped himself into the cockpit on Sept. 26, he was reasonably assured of the outcome.

“I’ve found the fun is in the planning,” Pratt said. “It’s a real challenge to make the flight, however, both mentally and physically.”

Friend and co-worker Tom Bishop said Pratt is fanatical about planning his world record attempts.

“He’s a detail freak. He gets excited about the details. You should see. His mind never stops,” Bishop said.

Pratt finds it difficult to understand why more people have not competed for ultralight records. The craft are among the most numerous in the world, they are inexpensive and the Federal Aviation Administration does not require pilots to be licensed.

Type R aircraft have a poor reputation, Pratt said, because some manufacturers produce flimsy craft and fail to educate prospective pilots about what the plane can do. If anything, Pratt said, his records have proven that microlights have “big aircraft” performance abilities and should be more strictly regulated.

“Even if you go by the letter of the law, you can fly yourself up 1,000 to 2,000 feet and fly yourself into an airliner,” Pratt said. “I’m a firm believer in education, no matter what kind of airplane you’re buying.”

Pratt, who has flown his Silver Eagle as high as 12,000 feet--is already planning how he will go for the altitude record. It will require additional modifications to the aluminum-winged craft, which has been designated experimental by the FAA.

To complement the small fuel tank beneath the pilot’s seat, Pratt has installed two fuel cells in each wing, for a total capacity of 15 gallons.

Fuel won’t be as much of a problem as breathing, however. At 20,000 feet, the air is thin for both humans and small gasoline engines.

Pratt said he is looking for a small jet engine, similar to the one in the military cruise missile, to power his plane toward the record altitude. If he’s unable to acquire a jet engine, he plans to turbocharge the 23-horsepower, two-stroke engine now on the plane. He also plans to take along a small oxygen tank.

Going almost 4 miles high in an airplane that weighs less than a big motorcycle must take a little bit of a daredevil spirit, right?

“I think most of my friends know that’s really not true. The interest is mostly scientific,” Pratt said.