LESS BANG FOR THE BUCK SONIC-BOOM SCIENTISTS SEEK NOISE CONTROL.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - Rosamond residents are used to the familiar pops of sonic booms from their flight-test neighbors at Edwards Air Force Base, but the morning of June 15 was more rocking than usual.

Seventeen sonic booms were cracked that morning in support of research aimed at reducing the annoyance factor of the loud bangs. On the ground below the aircraft's flight track, the research team was operating sensitive microphones to make detailed recordings of the booms.

``This data will be used to identify features of the boom, which improve the realism of laboratory simulations,'' said Peter Coen, Supersonic Vehicle Sector manager at NASA's Langley Research Center in Virginia. ``Eventually, these improved simulations will be used ... to identify what levels of sonic-boom noise are not offensive to ground observers. This information, in turn, will be used by NASA and industry to develop technology for future supersonic aircraft that are environmentally and community friendly.''

NASA's Dryden Flight Research Center at Edwards assisted with the June 15 flight-test work. Three F-18s from Dryden made a series of supersonic passes, flying at different altitudes from 32,000 feet to 45,000 feet and at speeds of roughly 910 mph to 980 mph, said Ed Haering, a sonic boom research at Dryden.

The sonic booms were recorded with high-performance microphones. The researchers also used a group of 18 volunteers to listen to both the original booms and simulated booms to give their impressions on the accuracy of the simulations.

The effort included placing instruments both inside and outside a vacant home on base to measure the booms and the impact they had on wall shaking.

``It's going to take weeks and months to analyze the data,'' Haering said.

No additional flights are currently planned in the tests.

Sonic booms occur as supersonic aircraft push aside air molecules with great force. This forms a shock wave, much as a boat creates a bow wave. The bigger and heavier the aircraft, the more air it displaces, NASA officials said.

The shock wave creates a cone of pressurized air molecules that move outward in all directions and extend to the ground. As the cone spreads across the landscape along the flight path, there is a continuous sonic boom along the full width of the cone's base. For now, supersonic aircraft are restricted to flying over certain test ranges in the United States. Developing technologies to lessen the impact of the booms could open the national airspace to supersonic business and commercial flights.

The research is being conducted by a consortium sponsored by NASA and North American regulators from the U.S. Federal Aviation Administration and Transport Canada. The consortium is conducting a series of research programs aimed at addressing environmental and quality-of-life issues as the aviation industry advances.

The consortium, called the Partnership for Air Transportation Noise and Emissions Reduction or PARTNER Center of Excellence, includes several universities, aircraft engine manufacturers, major defense contractors, private aircraft manufacturers and an airline.

Researchers at Pennsylvania State University and Purdue University are assisting with the project.

Jim Skeen, [phone]

james.skeen(at)dailynews.com