HVDRonvx AMirs IN SHIP nrsiGX 



Sec. H.3 



Moment Coefficient C^ 

 0.0 0.1 O.Z 0.3 a4 0.5 



DroqCoefft., Flo't Side EcJoe! 

 f?bund Side Eaqc 



0.0 Q2. 04 0.6 08 



Drag Coefficient Cd 



^"Z^ 



Fia. 41. B Lift-Coefficient, Drag-Coefficient, 



AND Moment-Coefficient Graphs for GOttingen 



Profile 409 of Aspect Ratio 0.5 



To prevent confusion, mo.st of the marks for 

 specific angles of attack are omitted from Figs. 

 44.A and 44.B. In Figs. IG and 17 of NACA 

 Technical Note 798 there are small circles along 

 the moment-coefBcient graphs but no numerals 

 to indicate the numerical values of a. 



Tables of coordinates for the symmetric 

 Gottingen section 409, as well as for Gottingen 

 sections 410, 411, 443, 429, 539, 639, and 640, 

 with lift, drag, and moment coefficients, are 

 given by W. P. A. van Lammcren, L. Troost, and 

 J. G. Koning in Tables 3 and 4 on pages 324 and 

 325 of RPSS, 1948. 



It is pointed out here, and it will again be 

 pointed out in later portions of this chapter, that 

 the behavior of a foil in water or in air is often 

 influenced critically by small changes in its 

 section. No performance data are acceptable for 

 design and other purpo.ses in practice, therefore, 

 unless accompanied by a delineation (and pref- 

 erably al.so a table of coordinates) of the section, 

 in sufTicicnt detail to permit it to be reproduced 

 to large scale. 



For the physicist, engineer, or architect who is 

 looking for a comprehensive compilation of airfoil 

 data in systt-inatic form tliere is available a 

 summary of airfoil data prepared and published 

 by the National Advi.sory Cfimniittce for Aero- 

 nautics in Washington [.Mtbott, 1. 11., Von 



D«KMihofT, A. i:., and Stivers, L. S.. Jr., NACA 

 Rep. 824, 1945]. This report contain.s, in addition 

 to the usual information on airfoil shape and the 

 customary experimental data, a considerable 

 amount of information on pressure distribution 

 over the airfoils illustrated. 



For the specific needs of the marine architect in 

 predicting the behavior of simple movable hydro- 

 foils of the shapes, sections, and proportions 

 required in ship design there are several useful 

 sources of information. These appl^' principally 

 to hydrofoils of sj'mmetric section and to aspect 

 ratios in the smaller ranges. 



I. Data on Thin Rectangular Plates of Aspect 

 Ratio 5.0, 1.0, and 0.20. In PXA, 1039, Vol. II, 

 Fig. 6 on page 204, K. E. Schocnhcrr gives curves 

 of normal-force coefficient and ratio of (1) distance 

 of center of pressure CP from leading edge to 

 (2) chord length of plate, on a base of nominal 

 angle of attack in degrees, for three flat plates 

 tested at Gottingen [Flach.sbart, 0., "Mcssungen 

 an ebenen und gewolbten Platten (Measurements 

 on Flat and Curved Plates)," Ergebnisse der 

 Aerodynamischen Versuchsanstalt zu Gottingen, 

 1932, Vol. 4, p. 9GfT]. Included are graphs for one 

 of the test plates of Joessel, but with no informa- 

 tion as to its aspect ratio. 



II. Data on NACA Symmetrical Airfoil Sections 

 with tx/c Ratios of 0.06, 0.12, 0.18, 0.25, and 

 Aspect Ratio 6. In PNA, 1939, Vol. II, pages 

 205-206, K. E. Schoenherr gives curves of lift 

 coefficient, drag coefficient, and ratio of CP from 

 leading edge to chord length of the hydrofoil. 

 The section ordinatcs are given, together with a 

 procedure (explained in the text) for converting 

 the given data to that which would be expected 

 for aspect ratios other than 6. The data are taken 

 from a report by E. N. Jacobs and R. E. Anderson 

 ["Large Scale Characteristics of Airfoils as Tested 

 in the Variable Density Wiiul Tunnel," NACA 

 Rep. 352, 1930]. 



Additional data are given Ijv E. N. Jacobs, 

 K. E. Ward, and R. M. Pinlierton in NACA 

 Report 460, publi-shed in 1933 (pages 299-354 of 

 the volume for that year), entitled "The Charac- 

 teristics of 78 Relatetl Airfoil Sections from Teats 

 in the Variable-Density Wind Tunnel." 



III. Data on Hydrofoils Having Symmetric 

 Sections and Outlines Suitable for Ship Rudders, 

 with Aspect Ratios of 0.5, 1.0, 1.5, and 2.0. In the 

 early 1930's there was tested at the Experimental 

 Mcxlcl Ha.siii ill Wa.shingloii a scries of twelve 



