points, then the number of different free-diving instrumentation capsules 

 built so far, although numerically substantial, is indeed meager. As a 

 matter of fact, it may not be farfetched to postulate that the future of 

 glass and ceramic deep submergence manned submarines would be more assured 

 and would arrive sooner if more efforts were directed at the present time 

 to design, fabrication, and evaluation of glass and ceramic deep submer- 

 gence free-diving oceanographic capsules and ASW weapon hulls, rather 

 than to feasibility studies of manned glass and ceramic submarines. The 

 more deep submergence free-diving capsules and ASW weapon hulls are 

 designed and built from these materials, the more engineering problems 

 pertaining to the use of these materials in deep submergence structures 

 will be brought to light and, after some experimentation with design 

 parameters, solved. 



So far, the design and fabrication of free-diving oceanographic cap- 

 sules and of submarines has pivoted around two dissimilar approaches to 

 the problem of providing more buoyancy for the carrying of larger payloads. 

 One approach relies on the design and fabrication of progressively larger 

 hemispheres, which, when joined, provide more and more payload- carrying 

 buoyancy. The other approach, to which the author personally subscribes, 

 is to provide increasing amounts of buoyancy, not just by building larger 

 and larger monolithic hemispheres whose size is severely limited by the 

 fabrication capability of the glass and ceramic industry, but by joining 

 many cylindrical shell sections into longer cylindrical hulls. 



The reason for using spherical hulls is obvious; it is an extremely 

 simple design, requires no stiffeners, and an ordinary glass to glass 

 joint will satisfy the joint requirements, particularly when a metal band 

 is used on the outside of the joint to hold the two hemispheres together. 

 The disadvantages of this approach to providing larger and larger buoyancy 

 for carrying of internal payload are many, the principal ones being the 

 poor hydrodynamic shape and severe fabrication size limitation, unless 

 polylithic designs and assembly methods are resorted to, at which time the 

 joint problem becomes much more complex and difficult than the joint for 

 cylindrical hull sections. 



The approach to the fulfillment of requirements for larger and larger 

 payload- carrying capabilities of free-diving capsules utilizing the concept 

 of joining several cylindrical shell sections together is firmly rooted in 

 past ASW weapon engineering practice and in the evaluation of the glass 

 and ceramic industry in fabrication capability. The custom of using cylin- 

 drical shapes in ASW weapon hulls and free-diving instrumentation capsules 

 is grounded in the well-known property of cylindrical hulls to possess 

 less hydrodynamic drag than spherical hulls of equal displacement. Not 

 only that, their capability of carrying payloads can be varied according 



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