Appendix D 



FEASIBILITY STUDY OF EQUATORIAL RING FOR THE 

 ATTACHMENT OF THE ACRYLIC PLASTIC CAPSULE 

 TO THE FRAMEWORK OF A SUBMERSIBLE SYSTEM 



INTRODUCTION 



Although the external cage type of capsule restraint (Figure 8) was 

 selected as the most applicable for securing the 66-inch capsule to the frame- 

 work of the NEMO system, this does not indicate that the other types of 

 restraint discussed in detail in the main body of the report are not applicable 

 if the design requirements of the submersible system are different from that 

 of the 66-inch first-generation NEMO system. Since the acrylic plastic 

 capsules will be incorporated into submersible systems distinctly different 

 from the first-generation NEMO system, some of the other capsule restraint 

 concepts warranted exploratory investigation. Of the five feasible approaches 

 previously discussed (Figures 5 through 9), only the bolt-on internal tie rod, 

 the equatorial ring, and the external cage types of restraints appeared to show 

 real versatility. For this reason, they were chosen for further exploratory 

 investigation. The internal tie-rod restraint was utilized in most of the models 

 tested for the acrylic plastic capsule program (Figures 15 and 64), and thus 

 does not require here any further discussion. The bolt-on restraint was used 

 during the extensive testing of the 66-inch-diameter large-scale capsule proto- 

 type (Figures 70 and 101), and for this reason no further experimental work 

 was needed on this type of restraint. The external cage restraint was chosen 

 for evaluation in the construction of the first generation operational NEMO 

 system built by the Southwest Research Institute, and thus the only type of 

 capsule restraint that remained to be evaluated was the equatorial ring type. 



EXPERIMENTAL PROGRAM 



The exploratory experimental evaluation of the equatorial ring capsuh 

 restraint concept consisted of designing and fabricating a 15-inch-OD x 14- 

 inch-ID acrylic plastic capsule that would be attached to the submersible's 

 exostructure by means of an equatorial ring incorporating the essential 

 features of that concept. The essential features of this concept (Figure D-1 ) 

 were: (1) an equatorial ring (Figure D-2) to which were attached the capsule, 

 the exostructure of the submersible, and the lifting slings; and (2) tapered 

 pins that were rigidly seated by means of threaded nuts (Figure D-3) in the 

 hull of the acrylic plastic capsule, while in the equatorial ring they were 

 restrained only from lateral displacement but were permitted to translate 

 radially by sliding in oversize holes drilled radially into the ring. 



187 



