Detail Design 



Once the design parameters pertaining to material selection, shape 

 configuration, operational depth, and assembly technique were selected, the 

 detail design of the capsule could begin. The detail design was concerned 

 with eight focal points: 



( 1 ) Means of ingress and egress for the capsule occupants 



(2) Penetrations for electric and hydraulic conduits 



(3) Attachment of the capsule to other structural systems 



(4) Attachment of life-support equipment, chairs, and control 

 console to the capsule interior 



(5) Magnitude of permissible working stresses in the acrylic 

 plastic and steel structural components 



(6) Specification of construction materials 



(7) Selection of hull thickness 



(8) Structure and component dimensioning 



Ingress and Egress. The access to the interior of the capsule could be 

 achieved in several ways. The capsule could be separated into two hemispheres 

 joined together by a mechanical lock that would permit opening of the top 

 hemisphere for personnel access. Another approach to the same problem 

 would consist of placing a hatch in the polar region of the sphere (Figure 3). 

 The latter approach was chosen as it permitted egress from the capsule even 

 when it was floating free on the ocean surface after emergency ascent without 

 additional buoyancy systems. Although from a structural viewpoint an acrylic 

 plastic hatch with a spherical bevel angle proposed by Piccard was the most 

 desirable one (when closed it did not introduce any appreciable stress concen- 

 trations into the acrylic plastic hull), a metal hatch system with a spherical 

 bevel angle was chosen for operational reasons (Figure 4). 



The rationale behind this choice was that (1) an acrylic plastic hatch 

 plug would soon lose its sealing ability because of surface scratches on the 

 seal surface generated by equipment and personnel passing through the hatch 

 opening, and (2) the metal would also act as efficient heat transfer surface 

 to depress the temperature in the capsule's interior. Without such a cooling 

 mechanism, pilots operating the capsule would soon become incapacitated 

 by the heat generated in the capsule's interior. A metal hatch plug and 

 matching ring insert would resist scratching more effectively and thus would 

 prolong the operational life of the ingress— egress mechanism. 



11 



