A 57-year-old Texas man died yesterday when the tiny experimental airplane he was piloting crashed into a group of parked cars as it was taking off from a small airfield in southern Prince George's County, Maryland state police reported.

They said Leroy Barto had just started the single-engine plane down the runway at Hyde Field in Clinton about 1:45 p.m. when witnesses reported seeing him "slump over the controls." The craft then veered off the left side of the runway, where it slammed into several parked cars and a pickup truck before coming to rest. There was no explosion or fire, police said.

Barto was taken to Southern Maryland Hospital where he was pronounced dead about 3:05 p.m., hospital officials said. An autopsy at the Maryland state medical examiner's office in Baltimore is scheduled for today.

No other injuries were reported in the incident, but another small aircraft that was parked near the site of the crash was slightly damaged by flying debris, police said.

National Transportation Safety Board spokesman Brad Dunbar said last night that the cause of the crash is under investigation and that it had not been determined if Barto lost consciousness before the craft went out of control.

James Jordan Jr., a pilot with whom Barto had been staying in Alexandria for the past month, said Barto was a mechanical engineer from Texas and was on leave from his job with the Bechtel Corp.

Jordan said Barto traveled around the country frequently and had been building the small airplane on his own for past two years until he finished it last Thursday.

"He had been working on it for about 12 hours a day out at the airfield," Jordan told a reporter last night. "He said he wanted to finish the plane so he could fly down to Texas to vist his family."

Jordan said Barto had recently passed a routine flight check with a Federal Aviation Administration official and that the plane was inspected and certified for flight.

The plane, called a "Quickie-200" by aerial enthusiasts, was constructed from a kit designed by a California-based firm that specialized in light, single-engine aircraft.

George Weiss, a lobbyist for Boeing Aircraft, and other pilots familiar with the design of the craft said its principal feature was an unusual tail section located at the front, which helped to increase the plane's speed.

"It seems unusual for the tail to be at the front," Weiss said, "but you have to remember the Wright Brothers did it that way."