NORTHROP DEVELOPS SUPERSONIC JET IDEA.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - Northrop Grumman unveiled its concept design for a long-range supersonic military aircraft that would produce sonic booms just one-seventh as loud as the Concorde's.

The design calls for a sleek, ``joined-wing'' airplane that is 156 feet long with a wingspan of 58 feet, its engine intake mounted on top of the fuselage and toward the aircraft's rear.

The design is part of the company's study work for the U.S. Defense Advanced Research Projects Agency's Quiet Supersonic Platform program, focused on finding breakthrough technologies to let an aircraft achieve long-range supersonic flight with minimal sonic-boom noise.

The program is not aimed at building an operational aircraft, but at providing technologies that could lead to new or improved bombers and fighters, reconnaissance aircraft and supersonic commercial aircraft, according to DARPA.

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

The technologies could lead to a small military supersonic strike aircraft that would perform more missions per day, deliver more weapons on target and provide a rapid, long-range response capability, DARPA officials said.

In conjunction with the study, Northrop Grumman is working on an effort to demonstrate how a sonic boom can be made quieter by modifying an aircraft's shape.

For the tests, Northrop Grumman will record a test of an F-5E fighter and then follow that flight minutes later with a modified F-5E fighter fitted with a specially shaped forward fuselage.

This ``back-to-back'' test approach is intended to highlight the effect that aircraft shaping can have on the mitigation of sonic booms, the company said.

Northrop Grumman Integrated Systems has successfully completed a critical design review of the modified F-5E with DARPA, an important milestone in preparation for the flights. The research flights, which will probably occur in early 2003, will be conducted at the NASA Dryden Flight Research Center at Edwards Air Force Base.

In addition to the studies being conducted by Northrop Grumman, DARPA also awarded a similar contract, valued at $2.6 million, to Lockheed Martin.

The objectives of the program are to create an aircraft that would weigh 100,000 pounds; cruise at speeds of Mach 2 to Mach 2.4, roughly between 1,400 mph and 1,680 mph; and have an unrefueled range of 6,000 miles.

By comparison, DARPA said, the Concorde weighs 400,000 pounds, cruises at Mach 2, and has an unrefueled range of 3,550 miles.

The program's goals are for the aircraft to create a sonic boom carrying an air pressure no greater than 0.3 pounds per square foot. A Concorde flying at an altitude of 50,000 feet creates a sonic boom of 1.94 pounds per square foot; a space shuttle returning to Earth causes a sonic boom of 1.25 pounds per square foot.

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Photo:

(color) An artist's conception shows a supersonic military aircraft with a new design developed by Northrop Grumman to lower the impact of the sonic boom.

Northrop Grumman