The Aerodynamics of Sails 



It then appears that the effect of heeling on sail aerodynamics is small. To 

 provide further confirmation of this fact, the downwash on a lifting line with an 

 end gap of five percent of the span of the lifting line was calculated for 0° heel 

 and 30° heel. These results are shown in Fig. Al. The difference in downwash 

 between and 30° of heel is discernable only near the bottom of the lifting line, 

 and the maximum difference is 4.5 percent of the value of the local downwash. 

 Therefore, accurate prediction and analysis of sailing rigs in the heeled condi- 

 tion can be carried out by proper resolution of forces and moments determined 

 in the non-heeled case. 



0.2 0,4 0,6 08 LO 



DOWNWASH VELOCITY FT,/SEC, 



Fig. Al - Downwash on a lifting 

 line with an elliptical circulation 

 distribution at zero and 30° of heel 

 (gap from the base of the lifting 

 line to the image plane is five per- 

 cent of the span of the lifting line) 



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