DEVELOPMENT OF A SPHERICAL ACRYLIC PLASTIC PRESSURE 

 HULL FOR HYDROSPACE APPLICATION 



Technical Report R-676 



YF 38.535.005.01.006 



by 



J. D. Stachiw 



ABSTRACT 



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 diameter models 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 specif- 

 ically 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. The experimental data indicate that the full- 

 scale NEMO capsule can be safely subjected to brief proof-test dives to 

 1 ,200 feet and routine operational manned dives of extended duration to 

 600 feet. 



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