McCormick 



Fig. 3 - TRI-B body exiting from water 



In view of these questions, the program at NTS was temporarily suspended 

 and the body returned to ORL for modification and laboratory tests. Tests were 

 conducted in the low turbulence wind tunnel at the Garfield Thomas Water Tun- 

 nel, a division of ORL, which showed that even at a length Reynolds number of 

 approximately 4.5 x 10 ^ lower than the design value by a factor of 8, extensive 

 laminar flow could not be achieved. In light of these results, the suction slots 

 were modified to assure a continuous suction around the circumference. When 

 this was done, laminar flow was achieved at the low Reynolds number over ap- 

 proximately 90% of the body as determined by listening to the noise of the 

 boundary layer with a total head tube connected to a stethescope. Hence it ap- 

 peared that the interruptions to the slots were the cause of the difficulties. 



At this time, tests were run to determine the suction coefficient, Cq, re- 

 quired to maintain full-length laminar flow for different length Reynolds num- 

 bers. Cp is defined as 



c - Q 



Q u s 



o w 



where s^ is the wetted area. 



suction velocity to free-stream velocity. 



1006 



