vertical stern and bow thrusters, one 

 fixed, reversible, lateral thruster fore 

 and aft and bow planes. 



f) DSRV-1 & 2 (Fig. 8.19n) has one fixed, 

 reversible, stern propeller, one each 

 (four altogether) fixed, reversible and 

 ducted, lateral and vertical thruster 

 fore and aft, port and starboard traina- 

 ble stern shroud. Roll is obtained by 

 transfer of mercury from one side to the 

 other. 



g) DEEP QUEST (Fig. 8.19o) has two fixed, 

 reversible, stern thrusters, two fixed, 

 reversible, ducted vertical thrusters 

 fore and aft, two fixed, lateral water jets 

 fore and aft (to provide sidle), hydrauli- 

 cally-operated stern dive planes and a 

 rudder. 



The degrees of freedom described for each 

 of the above vehicles were present at one 

 time and may still remain. It is obvious that 

 merely adding a thruster or re-orienting an 

 existing unit can change these motions. Such 

 changes have occurred in the past and there 

 is no reason to suspect that varying missions 

 might not prompt such changes again. 



While the approaches to maneuverability 

 have varied, there is a growing practice 

 among current builders toward laterally- 

 trainable stern propulsion units. This fea- 

 ture provides more responsive and controlla- 

 ble yaw motion without the aid of a rudder 

 and provides it at zero speed of advance. In 

 combination with a lateral bow thruster, the 

 180-degree trainable, stern propeller also 

 provides sidle motion. 



An interesting approach to steering and 

 propulsion was presented by Wozniak et al. 

 (13) and termed "Wake Steering." Wake 

 steering employs a propeller in a converging- 

 diverging nozzle with four slots through the 

 surface which may be selectively opened to 

 provide radial thrust (Fig. 8.20). Wozniak and 

 his associates offer the following explanation 

 behind the radial thrust producing forces. 

 "T/ie combined action of the vehicle 

 fonvard motion find propeller induced 

 flow results in a low ambient sttitic 

 pressure on the inside surface of the 

 nozzle, in fact, the propeller wake 

 attaches to the nozzle. By opening a 

 small port in the wall of the nozzle. 



exterior fluid is induced into the main 

 flow.This action results in a circum- 

 ferential variation of the interior pres- 

 sure and local separation of the wake 

 ichich in turn causes a net radial 

 thrust. Turning forces for various ma- 

 neuvers are thus developed by opening 

 one or a combination of ports. Pure 

 axial thrust is obtained when all ports 

 are closed.'' 



The wake steering concept had only under- 

 gone experimental and theoretical analysis 

 at the time of their report (1972) and, as the 

 authors concluded, produced more questions 

 than answers. It is described herein because 

 it is a fixed system which, theoretically, can 

 produce thrust, yaw and pitch motions with 

 only one propeller and a fixed, instead of 

 trainable, nozzle. 



MOTORS 



Regardless of the propulsor type or the 



PROPELLER 

 SUPPORT 



CONTROL PORT 



CONTROL 

 PORT 



BASIC STEERING NOZZLE & PROPELLER 

 CONFIGURATION 



Fig. 8.20 Wake sleering nozzle and propeller. |From Ref. (13)] 



388 



