TABLE 341.— FORCES ON MISCELLANEOUS BODIES 343 



The values of the drag coefficients in this table are based on the area of the projection 

 of the body on a plane normal to the wind direction. Where this projection is a circle, the 

 diameter is used as the linear dimension / in the Reynolds number. Where the projection 

 is rectangular, the shortest side of the rectangle is taken as /. 



Reynolds 

 Body Cd number 



Streamline bodies of revolution 05- .06 3,000,000 



Rectangular prism 1X1X5 normal to 1 X 5 face 1.56 180,000 



Rectangular prism 1X1X5, long axis perpendicular to 

 the relative wind and 1 X 5 face at 45° .92 254,000 



t about "I 

 300,000j 

 l~ about ~| 



Cone, angle 60°, point to wind, solid 51 |_270,000j 



Cone, angle 30°, point to wind, solid .34 270,000 



Hemispherical cup, open back .41 100,000 



Hemispherical cup, open front 1.40 100,000 



Sphero-conic body, cone 20° point forward .16 135,000 



Sphero-conic body, cone 20° point to rear .09 135,000 



Cylinder 120 cm long, spherical ends with 

 axis parallel to the relative wind .19 100,000 



TABLE 341A.— SKIN FRICTION ON FLAT PLATES (FIGS. 11, 12) 131 



If the flat plate is in a uniform stream of fluid and the flow is parallel to the plate the skin 



friction coefficient, O, is dependent mainly on the Reynolds number, R = ' The skin 



V 



friction coefficient Ct = — y where Dj is the friction drag per unit width of one side of the 



plate, q the dynamic pressure (see Table 339), and L the length from the leading edge 

 of the plate. 



For laminar flow 



Cr= — == (Blasius) 



VR 

 For turbulent flow 



Cr = (log™ RY™ *■ Scnlichtin s) 



The Reynolds number for transition from laminar to turbulent flow depends on the 

 roughness of the plate and the turbulence of the airstream. 



The figure shows the variation of the skin friction (Ct) with R for laminar and tur- 

 bulent flow. 



134 Tetervin, Neal, A method for the rapid estimation of turbulent boundary-layer thickness for calcu- 

 lating profile drag, NACA ACR No. L4G14, July 1944 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



