-11- 



Figures 33 and 34 Indicate that at speeds above 35 

 knots the two boat- type targets have appreciably less horizontal 

 drag than the TMB deslgn„ However, at speeds above 35 knots 

 the TMB design was the only model with adequate stability. No 

 data are shown for the two boat- type targets at a speed of 60 

 knots full-scale because at this speed both models porpoised 

 violently and uncontrollably „ At speeds above 35 knots full 

 scale both boat-type models porpoised if disturbed, the ampli- 

 tude and period depending upon the severity of the initial dis- 

 turbance o In some cases slight ripples on the surface of the 

 water, were sufficient to start porpoising. The TMB design did 

 not porpoise at any speedy even when violently disturbed,, 

 During the towing tests in the basin with cable, Part 1 of the 

 program, Model 4024, the revised G-60 sled, was the only model 

 which porpoised, and then only when towed from the after tow 

 point with maximum trim by the stern and at a full-scale speed 

 corresponding to approximately 27 knots „ ' 



CONCLUSIONS 



1. For a given displacement and initial trim, a change 

 in the position of the towpoint causes little change in the 

 resistance or directional stability of the targets. 



2, Towing the TMB design and the BuShips design W B H tar- 

 gets by a single cable in place of the conventional bridle results 

 in an appreciable reduction in target resistance but does not 



