|astronautix.com||First drop test of boilerplate 28|
North American conducted the first drop test of boilerplate 28 at Downey, Calif. The test simulated the worst conditions that were anticipated in a three-parachute descent and water landing. The second drop, it was expected, would likewise simulate a landing on two parachutes. The drop appeared normal, but the spacecraft sank less than four minutes after hitting the water.
Inspection of the vehicle immediately afterward disclosed that the heatshield had broken open on impact and that the welds of the stainless-steel honeycomb core had failed. The cabin interior also sustained considerable damage, especially the aft bulkhead and the cabin floor, which were forced upward and struck the crew couch. Three instrumented manikins were seated in the crew positions. The two outboard "crewmen" sustained 25 g's each at impact. The dummy in the second couch, however, suffered stresses of 50 g's, a condition that might euphemistically be called "unacceptable." MSC and North American personnel were investigating further.
In the week preceding the drop, the MSC Structures and Mechanics Division had sounded a note of caution. The aft heatshield, they said, "might not respond to the impact loading as static loading." In this event, they predicted, pressures imposed on the heatshield would "greatly exceed" design allowables. References: 16 .