Tables 143-145. ri2 



AERODYNAMICS. ^■^ 



The following tables, based on Eiffel, show the variation of the resistance coeflScient K, with 



the angle of impact i, the aspect (ratio of leading edge to chord length), shape and velocity V 



in the formula 



i?(kg/m2) = KS{m'){V{m/&ec.)\^ 

 The value of K for km/hour would be 0.77 times greater. 



TABLE 143. — Variation of Air Resistance with Aspect and Angle. 



Size of plane. 



Aspect. 



Values of i. 



3° 



40 



60° 



Values of Ki /Kx 



Max. ratio. 



Value. 



15 X 90 cm 

 15 X 45 cm 

 25 X 25 cm 

 30 X 15 cm 

 45 X IS cm 

 90 X 15 cm 

 90 X 10 cm, 



1,03 



1.02 

 1.02 



0.97 

 0.99 

 0.98 

 0,99 



1.07 



I. 22 

 1.46 

 0.91 

 0.77 

 0.69 



60 



45 

 38 

 20 

 20 

 15 



TABLE 144. — Variation of Air Resistance with Shape and Size. 



CyUnder, base _L to wind: 

 Diameter of base, 30 cm 

 Diameter of base, 15 cm 

 Cylinder, base 

 Cylinder, base 

 Cone, angle 60° 



6R* 8R* 14R* 



•059 



Length, o cm iR* 2R* 4^* 

 A' = .0675 .068 .055 .050 — — 

 K= .066 .066 .05s .051 .051 .0515 

 to wind: diameter base, 15 cm, length, 60 cm K = .040 

 to wind: diameter base, 3 cm, length, 100 cm K 

 diam. base, 40 cm, point to wind, soHd 

 Cone, angle 30°, diam. base, 40 cm, point to wind, soUd 

 Sphere, 25 cm diam. 



Hemisphere, same diam., convex to wind 

 Hemisphere, same diam., concave to wind 

 Sphero-conic body, diam., 20 cm, cone 20° 

 Sphero-conic body, diam., 20 cm, cone 20° 

 Cylinder, 1 20 cm long, spherical ends to wind 

 The wind velocity for the values of this table was 10 m/sec. 



Tables 143 and 144 were taken from "The Resistance of the Air and Aviation," Eiffel, trans- 

 lated by Hunsaker, 1913. 



* In the case of these cylinders the percentages due to skin friction are 2, 3, 6, 8, 11 and 16 

 per cent respectively, excluding the disk. 



TABLE 145. — Variation of Air Resistance with Shape, Size and Speed. 



This table shows the peculiar drop in air resistance for speeds greater than 4 to 12 meters per 

 second. Another change occurs when the velocity approaches that of sound. 



point forward 

 ■', point to rear 



060 

 A' = .032 

 K = .021 

 K= .011 

 K = .021 

 K= .083 

 K = .010 

 K = .0055 

 K = .012 



Shape. 



Speed, m/scc. 



Sphere, 16. 2 cm diameter 



Sphere, 24. 4 cm diameter 



Sphere, 33 cm diameter 



Concave cup, 25 cm diameter 



Convex cup, 25 cm diameter 



Disk, 25 cm diameter 



Cylinder cm 



element _L to wind, d = 1$ cm, I = 15.0 

 element _L to wind, 30 30.0 



element _L to wind, 15 7.5 



element -L to wind, 15 12.0 



element X to wind, 15 22.5 



element \\ to wind, 15 105.0 



Spherical ends, 15 120.0 



Values of K. 



033 

 025 

 023 

 090 

 027 

 071 



043 

 .045 

 .035 

 .038 

 .042 

 .069 

 .024 



030 

 025 

 017 

 090 

 022 

 070 



,042 

 032 

 034 

 037 

 ,041 

 .061 

 .022 



02S 

 021 

 012 

 089 

 021 

 070 



•037 

 .027 

 .032 

 .036 

 .038 

 .057 

 .019 



10 12 



027 



013 

 QIC 



087 

 022 

 070 



023 



031 

 032 



034 

 055 



oiS 



024 



QIC 

 GIG 



087 

 022 

 07c 



,02s 

 024 

 .031 

 ,030 

 031 

 ■053 

 .018 



.009 

 .OIC 



.010 



.088 



.021 



.07c 



.022 



.025 

 .031 



.02S 

 .028 



.052 



.018 



.0095 



.010 

 .oil 



.089 



.020 

 .070 



.021 



.025 

 .030 



.027 

 .025 

 • 051 



.017 



.010 



.DIG 

 ,012 



09s 

 ,019 



,070 



,022 

 025 

 030 



,025 



.022 

 051 



,Gl6 



.oil 

 .010 

 .012 

 . 100 



.018 

 .068 



.022 



.023 

 .030 

 ■ 025 



.020 



.050 

 .015 



Taken from "Nouvelles Recherches sur la resistance de Fair et I'aviation," Eiffel, 1914. 

 Smithsonian Tables 



