Water Jets 



The French SP-350 (Fig. 8.7) and the two 

 SP-SOO's are the only submersibles known to 

 use water jets as primary propulsion sys- 

 tems. Lockheed's DEEP QUEST employs this 

 means also, but only for transverse augmen- 

 tation of its primary screw propulsion. The 

 heart of the SP-350 system is a stern- 

 mounted 2-hp electric motor-driven water 

 pump which drives seawater forward 

 through a "Y" shaped flexible tube to jets 

 mounted port and starboard on the vehicle's 

 brow. The jets are mounted so that a rack 

 and pinion movement can rotate them in 

 unison or individually from straight forward 

 to straight down. The inefficiency and low 

 speed of this system were known and under- 

 stood by Cousteau, but for scientific research 

 and underwater photography the advan- 

 tages of high maneuverability overrode its 

 disadvantages. 



A comparison study between a number of 

 the various propulsion devices described has 

 been conducted and the results presented in 

 a previously referenced report by V. E. John- 

 son and R. A. Barr (9). These authors sum- 

 marized the results of experimental data to 

 1965, regarding free propellers, nozzles, 

 ducts and tandem and cycloidal propellers, 

 and related these data to the hydrodynamic 

 performance of the propulsors. The report 

 provides guidance in the selection of systems 

 to satisfy propulsion and maneuvering re- 

 quirements. 



Two propulsion systems proposed, but re- 

 portedly never used on an operational sub- 

 mersible, are the tandem and varivec propel- 

 ler systems. 



Tandem Propulsion System (TPS) 



The TPS consists of two girdling bands of 

 blades near the bow and stern of a submers- 



Fig. 8 7 Propulsion lor SP-350 is provided by two water jets mounted port and startx)ard on ttie centerlme lorward Ttie port |et can be seen here pointing directly aft. (NAVOCEANO) 



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