



1 1 1 1 1 

 Notes: 







1 



. Heat source inside the 66-in. OD x 61 -in. ID acrylic 



•"\ 







plastic sphere generates continuously 1,700 Btu/hr 





2 



. Air inside the sphere is circulated by a 1/8-hp fan 



\ 





: 



. Water cooling the exterior surface of the sphere is 



X 





stagnant 











i 





A 



X 



\ 





\ I 













/ 

 s 



\ 

 \ 



\ 



A. 



Interior atm 



Dsphere 









\ 

 \ 









1 



lie plastics 



jrface 











36 72 108 144 180 216 252 288 



2 

 Time (minutes x 10 ) 



Figure 120. Influence of ambient water temperature on the temperature of the 

 atmosphere contained within the 66-inch-diameter capsule in the 

 presence of an internal heat source. 



SUMMARY OF FINDINGS 



1. The mechanical and physical properties of commercially available grade G 

 Plexiglas acrylic plastic plates procured according to NCEL specifications are 

 reproducible within ±10% from one plate to another in the whole 0.250-to- 

 4.0-inch-thickness range, and the average of these properties matches the 

 typical property values supplied by the manufacturer. 



2. Fabrication of acrylic plastic spherical shells from flat cast plates that 



(a) have been thermoformed in a female vacuum-assisted mold, (b) machined 

 into spherical pentagons, and (c) bonded together with PS-18 cement results 

 in pressure hulls with dimensional deviations of approximately +6% in thick- 

 ness and ±0.5% in sphericity. 



155 



