Arnold Engineering Development Center engineers and test operators in the Ballistic Impact Range S-3, affectionately known worldwide as the chicken gun, are launching hundreds of block-shaped projectiles to simulate pieces of external tank foam breaking away during flight and striking various parts of the space shuttle, such as the solid rocket booster.

The S-3 range got its nickname because, in normal use, experts fire chicken carcasses at a test target at varying speeds to simulate a direct bird-strike during in-flight conditions.

In the NASA tests, operators launch the blocks at various velocities and angles to simulate the different ways foam might strike the solid rocket booster.

Officials said these tests will help determine the effects of foam impact, provide information on the booster hardware's ability to withstand those impacts and help populate a database for future reference.

Sponsored by the Marshall Space Flight Center in Huntsville, Ala., the program consists of multiple phases being conducted at several test facilities across the country. AEDC's contribution involves a portion of the solid rocket booster impact testing.

"Many parts of the space shuttle are being impact-tested at different test facilities in the country," said Allard Beutel, NASA spokesperson.

"This creates a significant demand for a unique test capability, and the SRB Project is fortunate to have AEDC's test capability available and conveniently located."

Before each shot, employees cut each projectile to specified lengths, widths and weights to make sure it's successful.

"If the foam projectile is too loose in the barrel, it can cause the velocity to be lower than desired," said Lanny Bell, AEDC project engineer. "If the projectile is too tight, it could break in the barrel during launch."

Jeff Venable, procurement quality assurance representative for United Space Alliance, works with AEDC employees to make sure each projectile and target meets test specifications. United Space Alliance is the prime contractor for NASA's Space Shuttle program.

"The AEDC folks are fantastic," Mr. Venable said. "You can tell they are completely dedicated and professional. Everybody is working toward the same goal of getting the shuttle back to flight. Their attitudes and work ethics are tremendous."

During each shot, employees use high-pressure helium gas to launch the projectiles at speeds from 150 to 2,255 feet per second - between 102 and 1,537 mph - down a new 86-foot-long rectangular barrel, Mr. Bell said.

The targets include the struts connecting the solid rocket booster and external fuel tank, core panels representative of the thermal protection system materials and cover material for the range safety system antennae that would be used to abort a mission if sufficient damage occurred to the shuttle.

High-speed video cameras operating at up to 20,000 frames per second document the impact events and provide test experts a way to measure the projectiles' velocity.

Mr. Bell said strain gauges and accelerometers on the targets panels acquire data at a sample rate of 50,000 samples per second to provide information on the stresses the target sustains during the impact event.

"As we carry out the CAIB (Columbia Accident Investigation Board) recommendations for safe return to flight, it is imperative that we determine the tolerance of the space shuttle elements, including the solid rocket booster, to withstand debris strikes and understand the effects," said Jack Hengel, NASA Shuttle Solid Rocket Boosters project manager.

"These tests will identify impacts that result in component failures that may lead to loss of vehicle and crew. In these cases, changes will be required to either control the debris source, strengthen the component design, or both."

Arnold Engineering Development Center is the nation's largest complex of flight simulation test facilities. It's home to some 58 aerospace test facilities located at Arnold Air Force Base, Tenn., and the center's remote operating location Hypervelocity Tunnel 9 in White Oak, Md.

The test facilities simulate flight from subsonic to hypersonic speeds at altitudes from sea level to space. Virtually every high performance flight system in use by the Department of Defense today and all NASA manned spacecraft have been tested in AEDC's facilities.

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