padeye >. 



free-sliding fit 



between pin 



and opening in 



equatorial ring 



equatorial ring 



padeye 



.*- acrylic plastic hull 



permanently 

 attached support 

 framework 



Figure 9. Equatorial ring and pin 

 restraint for attaching 

 the acrylic plastic cap- 

 sule to the NEMO 

 service module. 



Another approach that was considered was an equatorial ring held in 

 place by radial sphere penetrators (Figure 9). The sphere penetrators were to 

 be tapered and made from plastic with elastic properties matching those of 

 the acrylic plastic hull so that no stress raiser effect would be introduced by 

 them. The fit between the pins and the matching holes in the equatorial ring 

 was to permit sliding of the pins when they move radially inward with the 

 shrinking capsule under hydrostatic loading. The capsule held by the equa- 

 torial ring basically would not be subjected to tensile loading as the major 

 forces generated by lifting of the NEMO system out of water would be 

 shunted around the acrylic plastic capsule via the lifting attachments to the 

 equatorial ring. The only tensile loading acting on the acrylic plastic capsule 

 would be caused here by the dead weight of the capsule suspended from the 

 plastic penetrator pins when being lifted out of water. When floating on the 

 ocean surface, there would be some tensile stresses in the hull, but they would 

 be well distributed around the hull circumference by the radial sphere pene- 

 trators in the equatorial ring. In view of the rather low weight of the capsule 

 and the large wall cross section, the tensile stresses generated by it would be 

 low. Although the equatorial ring method of attaching the capsule to the 

 NEMO service module is not particularly advantageous, it may become 

 so if the NEMO capsules become part of some other system in which it is 

 important to have the capsule attached to the submersible at its equator 

 rather than at the poles as it is in the NEMO system. 



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