Design Structure 



Characteristic 



Memory length required 





Vehicle 



6k of program firmware located in PROM 





2k of scratch-pad RAM. 



Console 



24K of program operated in RAM 





interactive with minifloppy disk. 



Table 2. NOSC/USGS Free-Swimming Submersible: Mechanical, 

 Electrical, and Software Characteristics Summary. 

 (Continued. ) 



lengthening of the vehicle to accommodate 25 lb of additional payload per foot 

 of extension. The frame itself, weighing only 10 lb in water, is constructed 

 of sealed, welded aluminum tubing. The open-frame configuration has the ad- 

 vantage of allowing the addition of new sensors or payloads by simply strap- 

 ping them onto the frame with little modification. A long, narrow configura- 

 tion was chosen to allow for minimum drag in the water. It is adaptable to a 

 closed external skin which would reduce the drag if even higher speeds were 

 required in the future. Four 7-in-diameter , underwater, 1-atmospheric pres- 

 sure housings, containing most of the vehicle electronics, are strapped to 

 support brackets welded onto the main frame. Two 3-in-diameter bottles con- 

 taining the battery power pack are attached to brackets bolted to the lower 

 portion of the frame; this provides a reasonably good separation between the 

 center of gravity and the center of buoyancy. These battery housings are ap- 

 proximately 7 ft long and span almost the entire length of the vehicle frame. 

 They are 1-atmospheric pressure housings which are purged with nitrogen prior 

 to launch to remove any possible danger of a hydrogen-oxygen explosion. 



There are three thrusters which provide 3 degrees of freedom in the water 

 (two horizontal thrusters and one vertical thruster). The horizontal 

 thrusters are canted 15 degrees to provide a smaller turn radius. The motor 

 housings are oil-filled, pressure-compensated units designed and fabricated at 

 NOSC with commercially available Kort nozzles and propellers on each DC motor. 

 The canisters and motors are electrically interconnected using oil-filled, 

 pressure-compensated cables and connectors. 



A combination of 32- and 24-lb/ft' syntactic foam is used to provide 

 about 180 lb of buoyancy for the vehicle. The frame is bolted directly to 

 this foam with aluminum inserts. Metal parts exposed to the water are hard- 

 black anodized aluminum. The entire configuration is adjusted by trim weights 

 to be approximately 8 lb postively buoyant. The vehicle, designed to operate 

 down to a depth of 220(1 ft, submerges and maintains depth using the 20 lb of 

 thrust from the vertical motor. In an actual operation at such depths, it is 

 not anticipated that the vehicle would be driven down the entire distance by 

 the vertical motor. Instead, a weight would be used to aid the vehicle in 



20 



