  Volume 6, Number 5     September/October 1998

Aerospace Technology Development

Wind Tunnel Lined for Sound

NASA HAS COMPLETED A SOUND INSULATION project in the world's largest wind tunnel to help the U.S. aircraft industry design quieter engines and test advanced helicopters and other new aircraft. During the refurbishing that began in September 1994, workers installed a dense acoustic lining in the National Full-Scale Aerodynamics Complex (NFAC) at NASA's Ames Research Center at Moffett Field, California. The purpose was to reduce the test section's background noise and echoes during jet engine tests in the wind tunnel's 40-foot by 80-foot test section.

Background noise and echoes adversely affect the accuracy of sound measurement during jet engine tests, according to Project Manager Joe Hurlbut of Ames. Hurlbut said the refurbished wind tunnel will enable engineers to conduct very accurate acoustic tests.

Insulation material and 1,600 acoustic panels in the floor, walls and ceiling of the wind tunnel's 40-foot by 80-foot test section were installed. The new custom-made metal gray panels are made of perforated sheet metal bonded to stainless steel mesh, similar to that used in automobile oil filters. The insulation material behind the panels is similar to the spun fiberglass commonly used to insulate houses.

NASA engineers also upgraded the wind tunnel's control system to improve efficiency, and National Electric Company of Columbus, Ohio, modified the wind tunnel's main fan drive system to reduce noise. The Scott Company of San Leandro, California, served as the project's primary contractor.

Each of the wind tunnel's six fan-drive motors has 22,500 horsepower, for a total of 135,000 horsepower. These motors are capable of generating air speeds of up to 345 miles per hour in the 40-foot by 80-foot test section and up to 115 miles per hour in the 80-foot by 120-foot test section. Each of the six fans measures 40 feet in diameter and contains 15 variable pitch blades. The wooden blades weigh 800 pounds each and measure 15 feet in length.

Hurlbut said a series of technical problems, including the discovery of cracks in the fan blades in May 1995, delayed the completion of the project. The cracks have since been sealed with an epoxy resin, and the blades have been wrapped with a carbon and fiberglass composite to strengthen them.

Tests are scheduled to resume in the wind tunnel following the completion of the integrated systems testing in October. In November, Ames engineers are scheduled to begin a two-month test of the Subsonic High Alpha Research Concept (SHARC) aircraft. Sponsored by the Department of Defense and the U.S. Air Force, SHARC is a design concept being studied to improve the maneuverability of jet fighter aircraft.

For more information, contact Joe Hurlbut at Ames Research Center.
Call: 650/604-4953, Fax: 650/604-7197, E-mail: jhurlbut@mail.arc.nasa.gov
Please mention you read about it in Innovation.

Workers make aeroacoustic testing improvements by installing insulation material and acoustic panels of a 40-foot by 80-foot test section at Ames.

This overhead view of the refurbished test section at the Ames Research Center wind tunnel shows installed flow liner panels on the east door that allows for measuring low sound frequencies, resulting in more accurate acoustic tests for aerospace use.

SCIENTIFIC PAYLOADS TAKE COMMERCIAL FLIGHT

NASA has awarded a contract to a Maryland firm to procure excess space aboard commercial satellites for various scientific and engineering missions. NASA's Goddard Space Flight Center in Greenbelt, Maryland, has awarded a contract known as "Quick Ride" to Final Analysis, Inc., of Lanham, Maryland.

Under NASA's current contract consolidation initiative, any NASA Center and other government agencies will be able to purchase excess space aboard commercial satellites for various Earth science, space science and technology instrumentation payloads, resulting in faster, better, cheaper science missions.

During contract performance, NASA will develop a catalog for potential customers. It will include information regarding satellite launch dates, intended orbits and the configuration of available space for each contractor participating in Quick Ride."On-Ramps" is a precedent-setting contractual mechanism under the Quick Ride contract. It will allow NASA to solicit additional proposals and accept unsolicited proposals from commercial satellite firms during the contract's five-year performance period, to allow NASA to provide additional Quick Ride services to potential customers.

NASA's intent is for Quick Ride to conform with commercial industry practices. Government-provided instrumentation and/or payloads will be expected to conform to the accommodations aboard the commercial satellites to prevent any impact to commercial integration and launch schedules or primary payloads.

For more information, contact W. James Adams at Goddard Space Flight Center.
Call: 301/286-1289, Fax: 301/286-0530, E-mail: jadams@pop400.gsfc.nasa.gov
Please mention you read about it in Innovation.

NASA Official: Jonathan Root

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