A free-fall water impact of the nose section of the Challenger Orbiter including the crew compartment is investigated. Assuming the structure to be perfectly rigid, forces and accelerations acting on the capsule on entering the water are determined and compared with the survivability limits of the occupants. The peak decelerations corresponding to terminal velocities of 140 and 180 mph (62.6 and 80.5 m/s) were found to be 100 and 150 g, respectively, with a duration of approximately 25 ms. On the NASA human endurance diagrams, the calculated parameters fell within the area of severe injuries. The local pressures were also calculated and found to be of an exponentially decaying character with a maximum value in the range of 4-6 MPa (600-900 psi). A simplified rupture analysis of the outer shell acted upon by the transient pressure pulse was performed and it was found that tearing and fracture of the fuselage will certainly occur almost instantly on contacting water. It can be concluded that abrupt decelerations and loss of integrity of the cockpit upon water impact must have produced severe or fatal injuries. The present findings also shed some light on the problem of survivability of the primary explosion.
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