pitch angle is 2.5 degrees (bow up) , the experimental results are larger than 

 those frosa computation for essentially all Froude numbers (aee Figure 12). As 

 shown in Figure 13, negative pitch angle of 2.5 degrees (boy down), the 

 prediction and measurement of vertical force are, for the most part, in better 

 agreement than those for zero or positive pitch angle. The computed moments are 

 larger than tha experimental results for all submergences and Froude numbers. 

 These discrepanciea for non-zero pitch angle might be caused by the viscosity of 

 the fluid and also vortex shedding from the body or the cross flow effect. 



Figure 14 shows the results of lift for a hydrofoil whose section has the 

 shape of NACA 4412. The results shown in this figure are those for a two- 

 dimensional section. The agreement between computation based on the present 

 method and experimental data from Reference 14 is good when the angle of attack, 

 is smaller than 4 degrees (see bottom figure). As the angle of attack 

 increases, the computed results become larger than the measurements particularly 

 at the lower Froude number. It is of interest to observe that for this sub- 

 mergence the lift coefficient at the higher Froude number is smaller than that 

 at the lower Froude number. When the angle of attack is 10 degrees and the 

 Froude number is 0.922 (see top figure) there is substantial discrepancy between 

 the computed and experimental results as the submergence increases. The results 

 computed by the present method are further compared with the method developed by 

 Wadlin and Christopher in Reference 17, Equation (15). The calculations were 

 made for an aspect ratio of 10 to stimulate a two-dimensional lift coefficient. 

 It should be pointed out that Equation (15) of Reference 17 is strictly 

 applicable for aspect ratio of 0.125 to 10. Their results are almost half of 

 those by the present method. Compared with the experiment, the results of 

 Wadlin and Christopher show better agreement than those by the present method. 



Figure 15 shows the results of lift for a hydrofoil whose section has the 

 shape of NACA 64A010. The aspect ratio of this hydrofoil is 6. As shown in the 

 bottom figure, for small angle of attack there are small differences between 

 computation and the experimental results taken from Reference 15. The differen- 

 ces increase as the angle of attack Increases. The reason for these discrepancies 



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