Figure 58. Operational 15-inch-diameter model acrylic plastic capsule for 

 NEMO system: disassembled. 



The large-scale test series consisted of a single 66-inch-OD and 

 61-inch-ID acrylic plastic hull equipped with operational end plates of 

 type 316 stainless steel (Figure 66). The hull, as previously described under 

 "Fabrication Process," was fabricated in much the same way as the model 

 hulls. The bottom plate was a faithfully scaled-up copy of the operational 

 bottom plate in the model NEMO with the exception of the internal retain- 

 ing flange, which was bolted to the bottom plate instead of being threaded 

 to it (Figure 67). The top hatch was also a scaled-up version of the 

 operational hatch used in the NEMO models (Figure 68). The only differ- 

 ence between it and the working hatches in the models were the use of a 

 bolted-on, instead of screwed-on, retaining flange (Figure 67) and the use 

 of a planetary gear system, instead of a cam system, for the locking and 

 unlocking mechanism. (For detailed dimensions, see Appendix A.) Preten- 

 sioned tie rods were not used as (1) there would not be sufficient room for 

 them in a 66-inch capsule for manned operations and (2) absence of the rods 

 subjected the hull to a more severe test condition in the pressure vessel than 

 the capsule would see in actual service, where the external cage would resist 

 the downward pull of external ballast. 



Testing Program for Capsules 



The capsule test specimens were tested for their structural integrity 

 mostly by external hydrostatic loading. This type of loading was selected 

 because it represents (1) the most severe loading condition to which the 

 structure will be subjected in the ocean and (2) it is the loading condition 



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