NOSING INTO THE NOISE TESTS AIM TO KEEP AIRLINERS QUIETER.

Byline: Daily News

EDWARDS AIR FORCE BASE - Thirteen California Polytechnic State University, San Luis Obispo, students and an Air Force C-17 transport took part in a study aimed at designing quieter airliners.

The aerospace engineering students manned laptop computers on Rogers Dry Lake as the big jet flew overhead for its noise to be measured by 17 microphones spread over 15 square miles.

NASA, the Air Force and Northrop Grumman Corp. partnered for the test flights. NASA researchers from Ames Research Center in the San Jose area and and Dryden Flight Research Center at Edwards led the collaborative effort.

The jet noise was measured as the plane made various landing approaches, including an unconventional ``simultaneous and noninterfering landing'' similar to a descending spiral.

Research participants, using laptops connected to GPS receivers and equipped with third-generation sound cards, collected data from the flights to validate a modeling tool for predicting SNI approach noise footprints.

The flights also tested the hypothesis that employing this landing approach could help keep aircraft noise within the airport land-use zone.

NASA is looking into the idea of a 100-passenger airliner capable of landing on a runway as short as 2,000 feet and with low-speed maneuverability that will contain its noise within the airport area.

``An aircraft that could use the shorter runways of smaller regional and community airports could bring commercial air travel to approximately 97 percent of the U.S. population because most Americans live within a half-hour of an airport,'' said John Zuk, NASA Extreme Short Take Off and Landing Vehicle Section manager at Ames.

``Preliminary results indicate that the SNI approaches will concentrate the noise footprint into a narrow area and that the flight can be conducted safely, with commercial-aircraft ride quality,'' said Zuk.

NASA research pilot Frank Batteas said the landing approaches were simple and safe.

``They were flown using the aircraft autopilot and navigation displays. With some software changes, the aircraft flight director could provide total flight guidance for these approaches including the SNI,'' he said.

Dennis Eckenrod, an American Airlines MD-80 captain, was on board the C-17 during the test mission. He evaluated the rate of descent from a pilot's perspective and from the acceptability level of an airline passenger.

``The application of this research and the ESTOL program could open a portion of the approximately 8,000 airports around the country not currently used for commercial air travel,'' said Eckenrod. ``These airports were built to accommodate propeller-driven aircraft rather than today's commercial jet-engine aircraft that require longer runways.''

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Photo:

Eric Kurth, an engineering student from California Polytechnic State University, San Luis Obispo, sits on Rogers Dry Lake as he records noise from a C-17.

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