RESULTS OP EXPERIMENTS WITH MODELS OP HIGH SPEED TOWING TARGETS 

 INCLUDING ESTIMATES OFFULL-SCALE TARGET DRAG AND CABLE TENSION 



ABSTRACT 



Five models of high-speed towing targets, two flat- 

 bottom sled-types, two vee-bottom boat- types from Bureau of 

 Ships designs, and one vee-bottom toboggan- type David Taylor 

 Model Basin design, were tested at the David Taylor Model Basin 

 and in the Potomac River in an attempt to develop an improved 

 type towing target. The models were towed in the basin (a) by 

 a long cable attached to the dynamometer, and (b) under the 

 towing carriage with load increments applied to simulate various 

 lengths of cable „ Subsequent tests were made in the Potomac 

 River to observe the maneuverability of the models when towed 

 in waves. Motion pictures were taken during the latter tests 

 to show the action of the models in a straight run and in turns. 

 Estimates of full-scale target resistance and horizontal cable 

 tension* are given for various speeds and lengths of cable. 



It was found that for a given displacement and 

 initial trim, a change in tow-point position, within the limits 

 covered by the tests, has little effect on target resistance 

 or directional stability. The resistances of the two boat- 

 type targets and of the TMB design target were appreciably 

 less when they were towed by a single cable in place of the 

 conventional bridle, but the effect on the directional stability 

 was small. When towed by the single cable the targets had a 

 tendency to be self righting, after deliberately being capsized. 



•» The terms horizontal cable tension and horizontal target- 

 plus-cable drag are used synonymously in this report. 



