INTRODUCTION 



Requests for calibration of sonar transducers at 

 depths beyond normal station capability are becoming more 

 frequent. The NEL solution to the problem is a system for 

 applying pressure to a transducer within an acoustically 

 transparent vessel. The acoustical transparency permits 

 other transducers involved in the tests to be located out- 

 side the vessel in their normal environment. 



MECHANICAL DESIGN 



The pressure vessel is cylindrical with elliptical 

 end sections. Fiber glass -consolidated resin providing 

 both acceptable wall thickness and acoustical transparency 

 is used for the walls of the capsule. A geodesic winding 

 pattern minimizes the amount of fiber glass required. The 

 radial strength of the vessel is increased by a cylindrically- 

 wound additional layer. The wall has a breaking strength 

 of several thousand psig. The consolidated windings were 

 vacuum-cured to reduce air entrapment. 



