Dynamics of Hydrofoils as Applied to Naval Propellers 



'Lf 



Fig. 7 - Lift coefficient at shock-free entry 

 conditions versus / /c and f„/c. 



Suction-Side Maximum Depression in Ideal Flow 



In operating conditions, the maximum value of the depression at a typical 

 point M on the suction side of a foil (see Fig. 1) may be easily obtained by means 

 of Bernoulli's equation, 



T^=^- (l+A'K,.A'V^,^.A'y,C,,)' 



1 , 



(10) 



%pv 



and substituting the value of f /c obtained by the relation (6): 



^ = f--.*^' 



-L/ 



■+^'v^ c 



a La 



(11) 



1 + K, 



For the basic thickness forms and mean lines considered in this report, 

 when lift coefficients and thickness ratios fall in the range of those normally in- 

 volved in the design of a naval propeller (generally Ci^c/t„ < 6), the point of 

 maximum depression on the suction side occurs at 60% of the chord from the 

 leading edge, whenever the required lift coefficient is obtained completely by 

 camber or 90% by camber and 10% by the angle of attack. From the basic data 

 tabulated in the NASA Report 824, the values of the various coefficients in rela- 

 tion (11), shown in Table 4 are easily obtained for that point. Substituting the 



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