Columbia Accident Investigation Board Updates Foam Testing

The Columbia Accident Investigation Board (CAIB) completed the first round of foam impact tests on the thermal protection tiles of the main landing gear door. These tests were conducted at the Southwest Research Institute in San Antonio, Texas.

Five tests were conducted using a nitrogen propelled gas gun. Projectiles ranging from 855 to 1800 cubic inches were shot from a 30-foot long barrel. The distances varied from six to nine feet, at angles from five to 13 degrees, and speeds from 700 to 827 feet per second .

“The first set of tests has been very successful in two respects. First, the tests have given us an opportunity to calibrate our equipment as well as to practice for the tests against the wing leading edge, said Scott Hubbard, CAIB board member. Second, they have confirmed the models that predicted little or no damage to the tiles at these small angles.”

Foam used in the test was made of BX-250, which is the same composition of the foam investigators believe struck the shuttle during the January 16 launch. Additional tests on related articles and Reinforced Carbon Carbon Panels are scheduled to take place through June.

Test 1

• Date: May 1
• Size of Projectile (Cubic inches/lbs): 855/1.19
• Speed (FPS) (Planned/Measured): 700/723
• Center of Gravity Of Impact: 5

Results: Three craters 0.75 x 0.25 x 0.25 deep: Two streaks, 17 and 25 inches long from projectile markings: No other coating/tile damage due to foam observed.

Test 2

• Date: May 2
• Size of Projectile (Cubic inches/lbs): 855/1.19
• Speed (FPS) (Planned/Measured): 700/717
• Center of Gravity Of Impact: 5

Results: No craters from foam impact: Two streaks, 3.5 inches long from projectile markings: No coating/tile damage observed.

Test 3

• Date: May 5
• Size of Projectile (Cubic inches/lbs): 1800/2.5
• Speed (FPS) (Planned/Measured): 700/725
• Center of Gravity Of Impact: 5

Results: No craters from foam impact: Two black streaks, 10 and 22 inches long from projectile markings: No coating/tile damage due to foam observed.

Test 4

• Date: May 7
• Size of Projectile (Cubic inches/lbs): 1201/1.67
• Speed (FPS) (Planned/Measured): 775/827
• Center of Gravity Of Impact: 8

Results: Four craters 3 x.75: Two streaks, 30 and 40 inches long from projectile markings: No other coating/tile damage due to foam observed.

Test 5

• Date: May 9
• Size of Projectile (Cubic inches/lbs): 1201/1.67
• Speed (FPS) (Planned/Measured): 775/787
• Center of Gravity Of Impact: 13

Results: Three small craters: Two black streaks from projectile markings: No other coating/tile damage due to foam observed. (Still under analysis).

The CAIB has not reached any final conclusions and has not determined the cause of the loss of the shuttle and crew. The board's final report will be issued later this summer.