11 



Timing Lines -*A °- 10 «■ 



sec 



T 1 









^ = 8.4 x 10 6 



Laminar Flow 



U = 1.2. knots 



/MV\V<y 



Jl'l 



E = 11.3 x io° 



Transitional Flow 



U = 1.6 knots 



hi'' 1 



V, 



V- 



,\v 



\\^l/^,.'" 



„.'" 



A^v<.- 



\ 



E = 12.7 x 10° 



Transitional Flow 



U = 1.8 knots 



^1,0 



VW\ 



"Vlfy 



v. 



,/S 



!/>, 



E = 1U.1 x 10 s 



Transitional Flow 



U = 2.0 knots 



'./^ 



'/"" 



,S„/\ 



'"',' 



M 



U*, v 



E = 17.6 x io s 



Transitional Flow 



U = 2.5 knots 



Wr 



v* 



.'.'. 



"V 



^/••^("fV^/*'.^''!^/' 



^.f^J^t 



*vv 



E = 22.9 X 10° 



Turbulent Flow 



U = 3-25 knots 



Figure 7 - Characteristic Oscillograms of the Development of 



the Turbulent Boundary Layer at Hot Wire 17 Without 



Artificial Turbulence Stimulation 



The low speeds are of particular interest in that the development of the tran- 

 sition zone and the regression of the laminar area can be followed. 



After the boundary- layer surveys the probes were removed from the 

 model and resistance tests were made to obtain a record of the changes pro- 

 duced on the drag of the model by the use of the various stimulators. In all 

 these tests care was taken to duplicate the conditions which were imposed for 

 the boundary-layer surveys. It must be noted, however, that in order to in- 

 stall and to remove the trip wire and sand strip all of the ballast (3900 lb) 



