1.0 

 0.8 

 0.6 

 0.4 

 0.2 

 0.0 



5 (PRESENT INVESTIGATION) 



AFTERBODY 1 (HUANG et a!.' 2) 



2(HUANGetal.i2) 



Figure 1 - Three Afterbodies 



effectively tripped the flow 0.39 in. (1 cm) downstream from the wire and, 

 because of the finite parasitic drag of the wire, the boundary-layer can be 

 considered to become turbulent at a virtual origin 5.4 in. (13.7 cm) up- 

 stream from the trip wire at a Reynolds number of 9.3 x 10 . The virtual 

 origin for the turbulent flow is defined such that the sum of the laminar 

 frictional drag from the nose to the trip wire, the parasitic drag of the 

 trip wire, and the turbulent frictional drag aft of the trip wire is equal 

 to the sum of the laminar frictional drag from the nose to the virtual 

 origin and the turbulent frictional drag from the virtual origin to the 

 after end of the model (similar to Reference 10) . The virtual origin 

 location was taken as the transition location at which the boundary-layer 

 changed from laminar to turbulent in the boundary-layer calculations. 



INSTRUMENTATION 

 A Preston tube with a 0.072 in. (1.83 mm) inside diameter was attached 

 and alined with the flow on the upper meridian of the stern to measure the 

 shear stress distribution. The Preston tube was calibrated in a 1 in. 

 (2.54 cm) diameter water-pipe flow facility described by Huang and von 

 Kerczek. A series of 0.031 in. (0.8 mm) diameter pressure taps were 

 embedded on the upper meridian of the stern at the Preston tube locations. 

 These pressure taps were connected to a multiple pressure scanivalve system 



