TEST APPARATUS AND PROCEDURES 



The towing tests were conducted in the high-speed basin of the David 

 Taylor Model Basin. Instrumentation used for the tests consisted of a 

 pendulum angle indicator mounted to the tow bail to measure its angular 

 attitude, a 1200-pound-capacity tension gage to measure tension in the 

 towcable at the detector vehicle, and a pendulum angle indicator to 

 measure the towcable angle at the point where the towcable was attached 

 to the towing carriage. The tension gage was connected between the body 

 and the towcable, and the signal leads from both the angle indicator and 

 tension gage were married to the towcable and connected to a strip chart 

 recorder on the carriage. 



For the first series of tests, the detector vehicle was towed in the 

 suspended mode on a 12.5-foot length of cable in the deepwater portion of 

 the basin at speeds from to 6 knots in 1-knot increments. The tension 

 in the towcable at the detector and 'the angular attitudes of the towcable 

 both at the detector and at the towing carriage were measured, and the 

 towing behavior of the detector vehicle was observed. 



In tests to determine the tracking behavior of the detector and the 

 maximum towing speed for the detector to remain in a survey attitude (on 

 the bottom) , the detector was towed on cable lengths of 12.5, 25, and 50 

 feet of cable at speeds up to 6 knots. The angle and tension values were 

 monitored for each speed and cable length while observations were made of 

 the tracking and lift-off behavior. These tests were made in the shallow- 

 water portion (10 feet deep) of the high-speed basin. 



In the tests to determine the effect additional weight has on the 

 tracking behavior and maximum survey speed, approximately 100 pounds of 

 sheet lead were added around the detector mechanism. The detector vehicle 

 was towed on 12.5 and 25 feet of cable at speeds up to 6 knots in the 

 shallow portion of the high-speed basin. The angular attitude and tow- 

 cable tensions were monitored for each speed and cable length, and ob- 

 servations were made of the vehicle towing and tracking behavior. 



TOWING BEHAVIOR 



The detector vehicle, in the suspended mode, towed steadily at each 

 speed up to 6 knots. There were no apparent oscillations, and the vehicle 

 towed directly aft of the towpoint with no yawing attitude. When the 

 vehicle was in its survey attitude on the 12. 5-, 25-, and 50-foot cable 

 lengths, it tracked directly aft of the towpoint with no yaw. The ex- 

 panded metal housing rolled along the bottom for all speeds up to about 

 3.5 knots on the 12.5-foot cable, about k.O knots on the 25-foot cable, 

 and about U.5 knots on the 50-foot cable. When the vehicle lost contact 

 with the bottom, it would cease to rotate. The addition of approximately 

 100 pounds of weight in the vehicle did not produce the desired increase 

 in rolling speed (speed at which the vehicle would leave the bottom) but 

 had no adverse effects on the tracking behavior. 



B-4 



