DEVELOPMENT OF A SPHERICAL ACRYLIC PLASTIC PRESSURE HULL FOR HYDROSPACE APPLICATION.

A spherical, acrylic plastic capsule has been designed for protection of man against the external hydrostatic pressure present at continental shelf depths. Experimental and analytical studies have been conducted to evaluate the performance of both the spherical capsule design and the acrylic plastic construction material at continental shelf depths. Results from testing twenty-two 15-inch-outside diametermodels and a large-scale prototype under short-term, cyclic, and long-term hydrostatic pressure indicate that the design and material chosen meet the requirements for safe operation at continental shelf depths. A prototype 66-inch-OD capsule of 2.5-inch wall thickness, and 4,000-pound positive buoyancy in seawater has been specifically developed for the NEMO Naval Experimental Manned Observatory system. The NEMO prototype capsule successfully withstood 105 simulated dives ranging from 250 to 2,400 feet prior to being tested to implosion at a simulated depth of 4,150 feet. Until more experimental data are generated on the fatigue life of the full scale NEMO capsule under different pressure loadings, the capsule is considered to be safe for manned operation only to the 600-foot depth. Author