340 



TABLE 340.— FORCES ON THIN FLAT PLATES AT ANGLES TO THE WIND 



(FIG. 6) (concluded) 



Conditions of experiments 



Aspect ratio 1 Aspect ratio 3 Aspect ratio 6 



, * , , A , , * , 



Authority 131 1 2 3 4 1 3 5 1 3 6 6a 7 



Span, cm 25 30.5 12 12 45 7.6 36 90 .72 30.5 30.5 45.7 to 91.4 



Chord, cm 25 30.5 12 12 15 2.5 12 15 12 5.08 5.08 7.6 to 15.2 



Thickness, cm 3 .32 .17 — .3 .025 .17 .3 .17 .117 .129 



Tunnel diam., cm 150 00 200 120 150 60 200 150 200 137 137 152.4 



Reynolds No. X 10" 3 . 210 382 55 42 126 10 55 126 55 64 64 153 



131 Authorities: 1, Eiffel G., Resistance de Fair et l'aviation, 2d ed., p. 231, Dunod et Pinat, Paris. 2, 

 Dines, Proc. Roy. Soc. London, A, Math, and Phys. Sci., vol. 48, p. 233, 1890. 3,Foppl, Jahrb. Motor- 

 luftschiff-Studiengesellsch., vol. 4, p. 51, 1910. 4, Riabouchinski, Bull. Inst. Aerodynam. de Koutchino, 

 Petrograd, vol. 4, p. 113, 1912. 5, Stanton, T. E., Air resistance of plane surfaces, Minutes of Proc. 

 Inst. Civil Eng., vol. 156, p. 78, 1903. 6 and 6a, National Bureau of Standards, private communication. 

 7, Knight, Montgomery, and Wenzinger, Carl J., Wind tunnel tests on a series of wing models through 

 a large angle of attack range, Pt. 1, Force tests. NACA Rep. No. 317, 1929. 



TABLE 340A.— VALUES OF DRAG COEFFICIENT C D FOR FLAT PLATES OF 

 DIFFERENT ASPECT RATIO NORMAL TO THE WIND ( a = 90°) 



Values of Cd for circular disks are practically the same as for a square plate. 



Aspect ratio 

 Cd 



1.12 



1.18 1.22 



1.24 



1.26 1.28 1.30 1.32 



2.00 



TABLE 340B.— FORCES ON 



NONROTATING 

 (FIG. 7) 132 



CIRCULAR CYLINDERS 



The drag coefficient Cd for cylinders whose axes are perpendicular to the relative wind, 

 the area A being taken as the product of the length L and diameter d, depends to a marked 



degree on the aspect ratio -7' the Reynolds number R, and the Mach number M. The 

 o 



figure shows the variation of the drag coefficient Cd with R for cylinders of infinite aspect 



ratio at very low Mach numbers. The drag coefficient Cd varies with Mach number in a 



manner quite similar to that of the sphere on Table 340C (figures 8 and 10). 



o 

 u 



12 



"10 I0 2 I0 3 10* 10* I0 9 



REYNOLDS NUMBER, R 



Fig. 7.— The drag coefficient Cd as a function of the Reynolds number R at low Mach 

 numbers for cylinders of infinite aspect ratios with axes perpendicular to the wind. 



Drag = CdAq, Reynolds number, R= — - » Mach number, M = — For q see Table 



V ^ 



339, V = air speed, p = air density, i\ = coefficient of air viscosity. 



13 = Wieselberger, C, New data on the laws of fluid resistance. NACA TN No. 84, 1922. Relf, E. F., 

 Discussion of the results of measurements of the resistance of wires with some additional tests on the 

 resistance of wires of small diameter. R. & M. No. 102, British ACA, March 1914. Wieselsberger, C, 



Further information on the laws of fluid resistance. NACA TN No. 121, December 1922. 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



