52 THE NAVY OCEAN ENGINEERING PROGRAM 



The third experimental phase, in progress, is examining a series of 

 specimens of conical acryHc windows of 30, 60, 90, 120, and 150 degree 

 included angle exposed for periods of 500 and 1000 hours. The windows 

 are instrumented to provide data on their rate of displacement through 

 their mounting flange. 



Other engineering analysis on the appHcation of concrete has included 

 the testing of typical spherically shaped models for 1500 psi operational 

 pressure. A 16 in. diameter waterproofed concrete model, with opera- 

 tional windows, hatches, and wire feedthroughs, under simulated design 

 depth, was tested as an indicator of how well a concrete pressure hull 

 with penetrations can withstand hydrostatic loads. Several identical 

 models with soUd steel, aluminum, and plastic penetration inserts were 

 tested. 



The models, with operational windows, hatches, and feedthroughs, 

 failed under short-term pressurization at simulated depths of 7400 ft, the 

 same depth at which models without any penetrations failed. When the 

 solid inserts possessed rigidity equal to or greater than the concrete, the 

 models failed at the same or higher pressure than models without penetra- 

 tions; on the other hand, when the inserts were less rigid than the concrete, 

 the models failed at significantly lower pressure. 



Acrylic huU models are being tested as part of the program to investi- 

 gate acrylic plastics as underwater hull material. Evaluation of acrylic 

 plastic hulls consisted of subjecting a series of 1 5 in. outer diameter, one- 

 half-inch-thick spheres with metallic hatches to long-term submersion at 

 simulated 560, 1120, 1680, and 2240 ft depths. Only the hull model sub- 

 jected to a simulated 2240 ft depth failed, after ten hours of continuous 

 pressure appHcation. The models under simulated 560 and 1 1 20 ft depths 

 did not fail after 3000 hours of pressurization, and the model at the simu- 

 lated 1680 ft depth was still intact after 1000 hours. 



Underwater lights, instruments, and electronic assemblies require both 

 waterproof and pressure-proof packaging for successful operation. Due to 

 the high cost, limited availabihty, and limited variety of commercial deep- 

 sea instrument housings, experiments were undertaken to explore the 

 applicability and usefulness of commercially available glass closures, such 

 as those used in vacuum technology and the chemical industry. These 

 items have the advantages of wide distribution in the laboratory supply 

 industry and low unit cost. Investigations are continuing to determine 

 their capability to withstand high hydrostatic pressure and to demonstrate 

 their utility in the undersea engineering field. 



