17 



TABLE 3 



Values of the Velocity and Pressure 

 Coefficients for the Elongated Body 

 of Revolution Computed by 

 Landweber's Method 



X 



y 





P 



\'"l 



0.9894 

 0.9446 

 0.8656 

 0.7554 

 0.6179 

 0.4580 

 0.2816 

 0.0950 



0.0409 

 0.0903 

 0.1324 

 0. 1643 

 0.1848 

 0.1956 

 0.1994 

 . 2000 



0.5450 

 0.9261 

 1.0619 

 1.0946 

 1.0864 

 1.0641 

 1.0416 

 1.0276 



0.7030 

 0.1423 

 -0.1276 

 -0.1981 

 -0.1803 

 -0.1323 

 -0.0849 

 -0.0560 



of the body. Hence, the pressure obtained between stations 0.8 and 1.0 on the body appear 

 low due to the retardation of the stream in approaching the mound. Although the theory given 

 in Appendix B does not give a good approximation for the flow approaching a mound, the in- 

 crease in velocity over the mound would produce a decrease in pressure coefficient of about 

 0.03. The increase in pressure obtained just ahead of the mound is of this order of magnitude. 



TORPEDO MODEL H-60 



A quarter body of torpedo model H-60 was machined out of wax and mounted on the side 

 wall in one comer of the tank; see Figure 2a. In order to simulate a body infinitely long, the 

 model was made 18 in. in length (which was as long as practicable) and was cemented to one 

 of the electrodes to increase its effective length. The parallel section of the model had a 

 radius of 2 in. 



The probing about the nose of this body for obtaining the potential gradients required 

 greater precision than for the other bodies because of the large curvature and the rapidly 

 changing potential gradient over this region. It was while working with this body that the 

 wire along the contour just above the waterline was introduced and that the 400-cycle alter- 

 nating current was substituted for the 60-cycle. These refinements became necessary because 

 the potential differences as well as the increments in arc length were small. Potential read- 

 ings were made at from 0.G2- to 0.03-in. intervals over short segments at different stations 

 along the body. Increments in arc length were obtained from Equation [16] from the measured 

 increments in x and y. With the use of the fine wire along the body contour, there was no 

 difficulty in reading the x and y coordinates in thousandths of an inch, and readings would 



