Cb 



LCR from® 



Effect of Studs = 



C-j- Stud.s 



C -J. Bare 



0.60 









0.6.0 



AH MocioLs 



No measurable cffoct 





0.70 













Soa ."^pccd 



Trial Speed 



0.75 



0.J8F 



1.037 



1.0-22 





1.50F 



1.0.30 Moan 



1.028 Mean 





2.57F 



1.090 1.050 



1.098 1.050 





3.46F 



1.068 



1.075 



0.80 



0.76F 



1,050 



1 .054 





1.4 5 F 



1.079 Mean 



1.081 Moan 





2.50F 



1.035 1.055 



1.037 1.060 





3.51F 



1.074 



1.070 



The average increase with the two fuller block coefficients is 5 to 6 percent. For the 0.75 

 C g, there appears to be some tendency for the increase in resistance with stimulation to be 

 higher the further forward the LCB, and therefore the fuller the forebody and entrance. The 

 0.80 C g does not show such a definite trend, however, and no generalization can be made on 

 this point. 



When trip wires were used in place of studs, there was no difference in the results 

 except for two of the 0.80 Cg models, when the service and trial speed ©values were 

 about 2 percent higher with wires than with studs. 



B 



For the models used in the main series to explore the effects of changes in — and 



B 



— ratios, turbulence was stimulated by tripwires, 0.036 in. in diameter, placed around a 

 H 



section of the model 5 percent of the length from the stem. This choice was made basically 

 on two grounds. .Although in general there was no difference in the results using studs or 

 trip wires, the latter did give the higher results on some fuller models, as described above, 

 and, secondly, a review of practices in other model basins indicated a more general accept- 

 ance of the trip-wire technique rather than studs. 



The results of the main series of models, from which all the contours of C^ and (£) 

 have been derived, were therefore consistent in that they were all measured on models fitted 

 with trip wires. 



A.4 



