Objective of Study 



The objective of this study was to explore analytically and 

 experimentally the feasibility of constructing a 120-inch man-rated, 

 pressure-resistant, transparent capsule for continental shelf operation 

 with a minimum life of 2 years and 100 dives to its operational depth. 



The capsule design was to be of general nature so that a scaled-down 

 version could be incorporated into many available or foreseeable hardware 

 systems designed for operation at continental shelf depths. 



The data generated in this exploratory study were to serve two 

 purposes: ( 1 ) they were to permit the cognizant certification authorities 

 to assess the seaworthiness of the 66-inch-diameter* capsules built during 

 this study for the NEMO system, and (2) they were to serve as a basis for 

 design of other pressure-resistant, transparent capsules of the same material, 

 but different configuration or dimensions. 



Background Information 



The idea that a pressure-resistant, transparent capsule is technically 

 feasible and that its use will make exploration of hydrospace more compre- 

 hensive and effective is not new. It was suggested by Professor Piccard 1 in 

 1956 that such a capsule could replace steel pressure hulls. He proposed 

 that a spherical capsule be assembled by bonding 12 spherical pentagons 

 cast from acrylic plastic for use in bathyscapes instead of the steel capsules 

 with viewports. In Professor Piccard's opinion, the wall of the capsule could 

 be made thick enough to withstand safely a depth of 6,500 feet. Since he 

 did not support the proposed concept of such a capsule with any experimental 

 or analytical data, and very little was known about the behavior of acrylic 

 plastic in complex biaxial and triaxial stress fields, the concept was considered 

 on a par with science fiction. Because of the prevailing lack of interest in 

 exploration of the oceans and the visionary nature of his proposal, the con- 

 cept was not acted upon. 



The next proposal for a spherical, transparent capsule was made by 

 Perry 2 in 1961. He envisioned a transparent sphere assembled from two cast 

 glass hemispheres joined by a mechanical lock located on the sphere's equator. 

 According to him, such a capsule, when incorporated into a suitable submers- 

 ible system, would permit the scientists to explore ocean depths in excess of 

 20,000 feet. The capsule would, according to him, withstand such depths 



For brevity, this and all further references to size will be understood to describe the 

 outside diameter only. 



