-3- 



During the model basin tests for resistance, without 

 simulated cable load, the boat type targets exhibited undesirable 

 porpoising at speeds above 35 knots full scale. The porpoising 

 was of sufficient severity to make it inadvisable to operate the 

 targets at these speeds. The TMB design did not show any ten- 

 dency to porpoise, even when violently disturbed. 



At high speeds and long cable lengths all of the 

 targets have practically the same horizontal cable tension, with 

 the exception of the revised G-60 sled-type target. For cable 

 lengths of 1500 and 2500 yards full scale and a horizontal cable 

 tension of 60,000 pounds, the estimated maximum speed attainable 

 for the respective cable lengths is practically the same for all 

 targets, with the possible exception of the sled- type target 

 mentioned above „ 



It is concluded, therefore, that the fundamental fac- 

 tors in the determination of an improved target sled are not 

 the conditions affecting target resistance or the target resis- 

 tance itself 9 but the cable drag, the target stability, and the 

 target maneuverability,, 



INTRODUCTION 



In April 1930 the Experimental Model Basin at the 

 Naval Gun Factory, Washington, D. Co, conducted experiments on 

 a series of models (1)* for the purpose of developing a 



* Numbers in parentheses indicate references on page 

 of this report. 



