Stewart and Poudrier 



instruments. At present, developmental work is under way on two types 

 of flotation systems, one of which should have general application to 

 any towed instrument used within a few hundred feet of the surface, the 

 other for use with instrument packages which may be lowered to extreme 

 depths, such as 20,000 feet. 



IVhile compressed gasses can be used near the surface, as the depth 

 increases their use soon becomes impractical, since the weight of a 

 cylinder which would contain the gas at a high enough pressure to 

 generate buoyance becomes too great. Tlierefore it was necessary to 

 investigate the use of liquids or solids which could be decomposed into 

 gas when required. 



Selection of the most practical chemical for gas generation then 

 became the subject for investigation. Tlie most important criterion was 

 generation of maximum buoyancy per pound of chemical, safety, ease of 

 initiation of reaction, etc., were also important. *The analysis is 

 based on Van derWall's equation of state for the gases of interest. 

 Hie important parameters are the molecular weight of the buoyant gas 

 and the stiochiometry of the reacting system. The data is presented 

 graphically as weight of chemical reagent needed per one hundred 

 pound, water weight, of system to be lifted as a function of sea depth. 

 Also included as parameters are the molecular weight of the buoyant 

 gases and the gas generating efficiency of the reagent chemicals. 



Again we were fortunate in being able to draw upon experience gained 

 by the Navy in torpedo recovery systems. The Naval Ordnance Test 

 Station in China Lake, California, was actively engaged in development 

 of gas generators employing hydrazine (N2H4) for creation of buoyancy 

 for salvage and recovery purposes, and had recovered items from depths 

 of over 2000 feet. One of their systems had been made ready for use in 

 the recovery of the lost nuclear bomb off Palomares. Although their 

 systems were not directly applicable to our purposes because of the 

 weight of the associated equipment required, it appeared that with 

 some redesign these problems might be overcome. Financial support of 

 the work at China Lake by the Supervisor of Salvage, Naval Ships 

 Systems Command, was a very valuable assist, and assignment of Mr. Jay 

 Witcher as project manager for both the salvage requirements and 

 instrument recovery gave us immediate access to the best available 

 experience in this area. NOTS, Pasadena had also conducted experimen- 

 tal work with recovery systems employing lithium hydride as a source. 



At this time we have under development instrument recovery systems, 

 employing hydrazine and light metal hydrides. Prototypes of both 

 of these systems are being tested at sea aboard USNS GILLISS in an 

 area near Bermuda this week. The hydrazine system is designed to 

 have a lifting capacity of 300 pounds at a depth of 20,000 feet and 

 the light metal hydride system is incorporated in a modular housing 



♦Details of the analysis will be published as a U. S. Naval Weapons 

 Laboratory Technical Memorandum. 



298 



