Technicians position microphones around the Orion launch abort system and crew module test articles in preparation for the second round of testing in the acoustic chamber at Lockheed Martin’s facilities near Denver on Aug. 16, 2011. The vehicle was bombarded by acoustic levels of 150 decibels to simulate conditions during launch and abort if necessary. Part of Batch image transfer from Flickr.

Technicians at Boeing’s Space Environment Test Facility in El Segundo, California position the CST-100 Starliner spacecraft inside an acoustics test chamber. This Starliner, slated to fly in Boeing’s Crew Flight Test (CFT), underwent an environmental qualification test campaign in March, experiencing rounds of acoustics vibration, thermal vacuum and electromagnetic interference and electromagnetic contamination testing. These tests prove Starliner’s design is capable of handling the harsh environments of launch, ascent and orbit and also prove that the electronics systems will operate in space and not interfere with other satellites or the International Space Station. CFT is Boeing’s crewed flight test of Starliner and part of NASA’s Commercial Crew Program, which will return human spaceflight launches into low-Earth orbit from U.S. soil.

The 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory was the largest supersonic wind tunnel in the nation at the time and the only one able to test full-scale engines at supersonic speeds. The 8- by 6 was designed as a non-return and open-throat tunnel. A large compressor created the air flow at one end of the tunnel, squeezed the flow to increase its velocity just before the test section, then reduced the velocity, and expelled it into the atmosphere at the other end of the tunnel. This design worked well for initial aerodynamic testing, but the local community was literally rattled by the noise and vibrations when researchers began running engines in the test section in January 1950. The NACA’s most modern wind tunnel was referred to as “an 87,000-horsepower bugle aimed at the heart of Cleveland.” NACA Lewis responded to the complaints by adding an acoustic housing at the end of the tunnel to dampen the noise. The structure included resonator chambers and a reinforced concrete muffler structure. Modifications continued over the years. A return leg was added, and a second test section, 9 -by 15-foot, was incorporated in the return leg in the 1960s. Since its initial operation in 1948, the 8- by 6-foot tunnel has been aggressively used to support the nation's aeronautics and space programs for the military, industry, and academia.