BOOM-CUTTING PLANE STUDIED.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - NASA and aerospace companies are studying whether it's possible to design and build an airplane that would reduce the startling impact of sonic booms.

Under the Sonic Boom Mitigation Project, NASA and its partners are looking at the feasibility of the concept and what design would be required for a prototype airplane to test boom-reducing technology.

``The concept exploration studies are crucial,'' said Peter Coen of the Langley Research Center at Hampton, Va., and a member of the Sonic Boom Mitigation Project planning team. ``Those studies will determine whether a low sonic boom demonstrator aircraft can be built at an affordable cost in a reasonable amount of time.''

The project would continue research conducted at NASA Dryden Flight Research Center that tested a fighter jet with a modified nose to show it was possible to use the shape of an aircraft to soften sonic booms.

As supersonic aircraft speed along, air molecules are pushed aside with great force and this forms a shock wave much like a boat creates a bow wave in water. The sharp release of pressure, after the buildup by the shock wave, is heard as the sonic boom.

The bigger and heavier the aircraft, the more air it displaces, NASA officials said.

A Concorde flying at an altitude of 50,000 feet creates a sonic boom of 1.94 pounds per square feet; a space shuttle returning to Earth causes a sonic boom of 1.25 pounds per square foot.

NASA awarded a grant to American Technology Alliances to fund studies being conducted by four industry teams, including Boeing Phantom Works; Raytheon Aircraft; Northrop Grumman, which is teamed with Gulfstream Aerospace; and Lockheed Martin in Palmdale, which is partnered with Cessna Aircraft Co.

The same grant is also funding Allison Advanced Development Co., Indianapolis; GE Transportation, Cincinnati; and Pratt and Whitney, Hartford, Conn., to support the teams with engine-related data.

Each team has been awarded about $1 million for a five-month study. NASA will use the results to define technology and design requirements for a low sonic boom demonstration aircraft.

``NASA plans to develop a request for proposals to design and build a low sonic boom demonstrator using the information provided by the teams,'' said Bob Meyer, Dryden's project manager for the program.

The questions the research will answer include whether it's feasible to modify an existing aircraft to be the ``quiet boom'' demonstrator, or whether a whole new aircraft design will have to be created, NASA officials said.

In late 2003 and early 2004, researchers from NASA and Northrop Grumman conducted flights with two F-5E fighters, one with a modified nose.

In tests, the standard F-5 registered a sonic boom measuring 1.2 pounds per square foot while the modified jet recorded a sonic boom at .8.

It might be possible to design aircraft with sonic boom pressures of just .3, researchers said.

Such technologies would allow commercial and military aircraft to fly unrestricted over land rather than being restricted to certain test ranges or - as in the case of the Concorde passenger jet - restricted to trans-Atlantic flights.

Jim Skeen, [phone]

james.skeen(at)dailynews.com