Lighter Than Air : Altitude record: Simi Valley’s Dave Timms takes his home-built Long EZ aircraft 30,500 feet up to new heights.

After Dave Timms set an altitude record in his home-built airplane Saturday, friends asked what he planned to do next.

“I’m going to go home and eat,” said Timms, who lives in Simi Valley. “I’ve been eating nothing but popcorn for the past three weeks.” The diet--which resulted in a loss of 15 pounds--was one of several ways the 54-year-old Timms found to lighten the load for his Long EZ aircraft. He got rid of another 40 pounds by removing the plane’s alternator, navigational lights, automatic-pilot mechanism and unnecessary radio equipment.

But Timms had to add an oxygen tank and breathing apparatus, which are necessary above 12,500 feet.

When pilot and aircraft weighed in Saturday morning at the Camarillo Airport, the total was 1,099 pounds--three pounds under the limit for his weight class, which ranges from 661 pounds to 1,102 pounds.

The bright yellow craft lifted off about 8:15 a.m. and headed southwest over the ocean, where Timms would be in no danger of running into commercial aircraft.

To set a record, Timms had to exceed by at least 3% the old record for his weight class: 27,040 feet, set last year by Robert L. (Hoot) Gibson, who was commander of Space Shuttle Endeavour in September. And he had to maintain that altitude for 90 seconds or 15 kilometers.

Somewhere south of Santa Cruz Island, Timms hit 30,500 feet--more than 5.7 miles up--and stayed there for five to 10 minutes, he said. On board was an barograph that the National Aeronautic Assn. will use to verify the altitude.

By radio, someone back at the airport asked Timms how he felt.

“Cold, very cold,” Timms replied. Later, he said the temperature was about 40 degrees below zero.

Timms, a laid-off tester of circuit boards for a Simi Valley electronics company, spent 8 1/2 years building the plane and has been flying it for about four years. It has a standard piston engine and a single propeller in the rear. The stabilizing wing found in the tail of most planes is in the front of Timms’ craft.

The plane was designed by Burt Rutan, who also designed the super-efficient Voyager plane that was flown around the world without refueling.

“This shows the capability of a really good home-built airplane,” said Jack Norris, Timms’ technical adviser. Timms agreed. “The future of general aviation is in home-built planes,” he said.