ward and the opposing one downward. 



b) Laterally trainable, stern-mounted pro- 

 peller with port/starboard, 360-degree 

 rotating thrusters amidships. ALVIN 

 (Fig. 8.18g), SEA CLIFF and TURTLE 

 fall into this group. 



c) Two reversible, fixed and ducted stern 

 propellers (pointing 15° outboard) and 

 two fixed, reversible, vertical thrusters 

 fore and aft. DOWB (Fig. 8.18h) can 

 obtain pitch by operating the thrusters 

 in opposition. 



d) Two fixed, reversible stern propellers 

 and one fixed reversible, vertical stern 

 thruster. SEA RANGER (Fig. 8.18i) em- 

 ploys this system. The vertical thruster 

 provides pitch and, it is believed, with 

 proper vehicle trim can also provide 

 heave. 



e) Two variable-speed, port/starboard 

 water jets mounted on the bow and ca- 

 pable of rotating 270 degrees in the ver- 

 tical plane. SP-350 (Fig. 8.18J) and SP- 

 500 use this system. 



f) One fixed, reversible stern propeller and 

 two port/starboard, reversible thrusters 

 capable of 360 degrees of rotation in the 

 vertical plane. SHINKAI (Fig. 8.18k) 

 uses this approach. 



Thrust, Yaw, Heave, Sidle: 



In this group are two submersibles, each 

 with a different means to the same end. 



a) The Navy's MAKAKAI uses two pi-pitch 

 cycloidal propellers, which were de- 

 scribed earlier. 



b) KUMUKAHI employs four reversible, 

 fixed, port/starboard thrusters, and one 

 vertical and one lateral thruster, both of 

 which are fixed and reversible (Fig. 

 8.181) 



Thrust, Yaw, Heave, Pitch, Sidle: 



Two submersibles obtain these motions ex- 

 clusively through propulsion alone: The 

 JOHNSON SEA LINK and DS-2000. 



a) The JOHNSON SEA LINK (Fig. 8.18m) 

 carries eight reversible propellers which 

 are arranged to provide the following: 

 Three trainable (90° port/starboard) 

 stern-mounted propellers provide 

 thrust and yaw. One bow-mounted 

 and laterally oriented thruster also 

 provides yaw and, in combination 



with stern propellers in proper orien- 

 tation, sidle. Two vertical fore and aft 

 thrusters provide heave and pitch. 

 Two port- and starboard-mounted, 

 fore-and-aft thrusters are situated 

 amidships to assist in thrust, 

 b) DS-2000 employs two fixed, reversible, 

 stern propellers, two fixed, reversible 

 fore- and aft-mounted vertical and fore- 

 and aft-mounted lateral propellers (Fig. 

 8.18n). 



Thrust, Yaw, Heave, Sidle, Roll: 



BEAVER has three reversible, 360-degree 

 rotatable propellers mounted in an inverted 

 "Y" configuration amidships around its hull; 

 through a variety of orientations and thrust 

 combinations five degrees of freedom are 

 obtained as demonstrated in Figure 8.I80. 

 Similar to NEMO, BEAVER also carries an 

 anchor and winch which can be used to ob- 

 tain a yo-yo-like heave motion and fore and 

 aft transfer of meurcury provides pitch. 



Control by Motors, Rudders 

 and Planes 



The greatest number of shallow diving 

 submersibles is found in the group relying on 

 rudders and planes, in addition to propellers, 

 to maneuver. The use of planes and rudders 

 has one obvious disadvantage: They are only 

 effective when the vehicle is underway; 

 thrusters are effective when the vehicle is at 

 zero speed. 



Thrust, Yaw, Heave: 



The two General Dynamics' submersibles 

 STAR II and STAR III fall into this category 

 and both vehicles' rudders are hydraulically 

 powered. 



a) STAR II (Fig. 8.19a) is equipped with 

 two fixed, reversible, stern propellers, 

 one fixed, reversible, vertical thruster 

 atop the vehicle just aft of the hatch 

 and enclosed within the fairing. A rud- 

 der is formed from the lower trailing 

 edge of a cruciform tail section. 



b) STAR III (Fig. 8.19b) utilizes one fixed, 

 reversible stern propeller, a vertical 

 thruster mounted similar to STAR //'s, 

 a fixed, reversible lateral bow thruster 

 ducted within the exostructure and a 

 rudder formed from the trailing edge of 

 its inverted Y-shaped tail section. 



385 



