filament- wound fiberglas need further development, but promise 

 to significantly reduce the cost of future pressure test facilities. 



A major problem facing the nation's pressure -test chambers 

 is that they wear out. The low cycle fatigue curve for typical large 

 high pressure (20-30 ksi) chambers shows that cyclic pressure 

 capability is only about 1/3 of the static capability. For a chamber 

 which is planned to be constructed at NSRDC Annapolis in 1970, 

 this curve shows that each time the full static pressure is reached, 

 the chamber deteriorates in value by about $700. Each cycle at 

 cyclic pressure reduces the value of the chamber by 70(;5. Typical 

 tests on deep ocean submersible equipnaent require on the order 

 of 50, 000 cycles. Many experim^enters don't realize that the life 

 of each pressure facility is limited. Of 269 major chambers cata- 

 logued in a recent nation-wide survey conducted by the Navy, only 

 a few of the owners had any idea of the remaining life of their 

 chambers. Design standards are virtually non-existent, so choice 

 of materials and designs varied radically among the chambers sur- 

 veyed. There have been 2 explosions of pressure chambers recently, 

 and based on this analysis we can expect more. 



One problem which will necessitate new design concepts for 

 larger pressure chambers is steel billet size. The largest steel 

 billet size in the U.S. is approximately 100 tons, and the fabrica- 

 tion of a chamber which will be operational this year at NSRDC 

 Annapolis approached this limit. Welding sections of this chamber 

 together also presented major difficulties. Filament- wound fiber- 

 glas is a promising development for overcoming this limitation. 

 A small pressure chamber using this concept has already been 

 cycled over 100, 000 times. This technology may permit very 

 large pressure chambers to be constructed on site at much lower 

 costs than are now possible. 



Non- Combatant Vehicles 



The weaknesses in our non-combatant vehicles stem primarily 

 from the shortcomings in the technological areas just reviewed. 

 Our efforts range from surface ships to deep submergence vehicles 

 to unmanned deep recovery systems. Design of support ships with 

 associated handling equipment which must handle submersibles in 

 the dynamic air- sea interface is a major problem. For manned 

 and unmanned vehicles, improved and new developments in ma- 

 terial, power, and vehicle auxiliary systems will lead to optimiza- 

 tion in terms of weight, volume, simplicity, reliability and main- 

 tainability. 



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