RAMON LOPEZ / NASA AMES RESEARCH CENTER
NASA and US aerospace industry researchers are using the Ames Research Center's 12m x 24m subsonic windtunnel and a 26% scale model of a Boeing 777 to see if design modifications can reduce the level of noise generated during deployment of the aircraft's landing gear, flaps and slats during take-off and landing.
The Subsonic Transport Acoustic Research (STAR) model replicates the left half of the aircraft and is mounted vertically in the tunnel. The model includes a 7m wing, landing gear, leading edge slats and trailing edge flaps that are fully extended to duplicate take-off and landing conditions.
Kevin James, NASA's lead engineer on the project, says the windtunnel test culminates eight years of work with 6% scale models. The latest series of tests is evaluating various devices at the same time to see how they work together. He hopes the research will yield a total 7dB reduction.
Researchers have bolted an end-plate on the edge of the flaps to alter the vortices caused by the interaction of upper and lower surface airflow, providing an estimated 4dB reduction. Hydraulic lines have been relocated and a fairing added to smooth the airflow around the 777's BF Goodrich-made landing gear. Hydraulic brake lines might be replaced by electric wires and actuators to "clean up" the landing gear, says James.
Some of the data is proprietary as NASA plans to seek patents, limiting the technology to US aerospace companies. The STAR team also includes Boeing and Lockheed Martin.
James says the improvements could be retrofitted on 777s and other Boeing airliners. "Some would be easy to incorporate. Some would be more involved," he says.
Source: Flight International
