F-7 



UARS 



(unmanned arctic research submersible) 



Operating Depth: i+5Tm ( 1,500 ft) 



Dimensions (LxWxH) : 3m x . 5m x . 5m (lO ft x 1.6 ft x 1,6 f t ) 

 Weight { 'DrfT- J+08kg (900 lbs) 

 S peed : 3-7 knots (6.8km/hr) (cruising) 



Structur e: Cylindrical shape composed of a pressure-resistant and filament- 

 wound reinforced plastic hull and a floodahle tailcone section which 

 supports the vehicle control surfaces (rudders and elevators) and 

 propeller. The vehicle is 9kg (20 lbs) positively buoyant when submerged. 

 Power : Silver zinc batteries supply all power. The batteries are divided 

 into two sources of supply: a 260 ampere hour main battery and a 60 

 ampere hour reserve. The main battery provides the normal 10 hour run 

 capability, the reserve provides slightly more than 2 hours running time. 

 Command/Control : A Vibrotron pressure transducer is used as the depth 

 control sensor. The vehicle can be commanded to any one of four preset 

 running depths, and can step up or down in small increments from any 

 of the preset depths by means of acoustic command from the tracking 

 station. Inputs from an obstacle avoidance sonar or an under-ice profiler 

 will send the vehicle to the next lowest preset depth each time a step-down 

 command is received from either unit. Roll control is provided by 

 two linear activators which activate the vehicle's elevator control 

 surfaces. The activators respond to a roll angle sensor mounted in the 

 vehicle. Primary heading reference is obtained from a directional gyro. 

 An initial heading is set before launching, heading changes (in 3 degree 

 increments clockwise or counter-clockwise) during the run are acoustically 

 commanded from the tracking station. The vehicle can also "home" on 

 an acoustic source whtn it is observed (via an acoustic telemetry link) 

 that the homing signal is above threshold level. The heading control 

 curcuits then switch control of the rudder drive circuits to the 

 output of the homing receiver. Stop "homing" can be commanded by acoustic 

 link at any time and heading control reverts to the directional gyro. 

 In the event that the vehicle does not receive a command for a period 

 of 5 minutes a "loss of command" sensing circuit actuates a l80 degree 

 turn in the azimuth stepping circuits, which reverses the vehicle's 

 course for a period of 10 minutes. If command is still not received a 

 homing search mode is activated. After one hour from loss of the first 

 command signal the motor stops and the vehicle floats to the surface. 

 Tracking of the vehicle (under-ice) is conducted by an array of four 

 separate hydrophones which receive an acoustic pulse every 2 seconds 

 from the vehicle which is referenced to a clock within the vehicle. 

 Slant ranges to the hydrophones are determined by the velocity-time 

 calculations. The hydrophone positions are monitored continuously by 

 acoustic means with respect to a transducer baseline which serves as 

 a base of reference. 



Instrumentati on: The primary purpose of UARS is to accurately profile 

 the underside of ice. To conduct this task an acoustic profiling system 

 is carried which measures and digitally records the under-ice profile 



