AERODYNAMICAL EXPERIMENTS UPON A YACHT'S MAINSAIL. 



Table II. 



The components c and d were derived directly from the equations and their 

 resultant gave the resultant wind pressure, in magnitude, direction, and point of 

 application (Columns 4, 8 and 11, Table II). Therefore it was possible to plot 

 this resultant wind pressure in its true location and to scale, for the different angles 

 of boom to wind ; this is done in Figs. 4 to 15, Plate 8. The maximum resultant 

 pressure occurred at an angle of boom to wind of 110°, which was not unex- 

 pected when it is noted that the gaff was then at about 80° with the wind and one 

 might consider that the mean line of the sail was at practically 90°. (All angles 

 were measured upstream from the initial position of the boom.) 



The maximum pressure amounted to 0.913 pound for the entire model at 



1 5. 1 miles per hour. This corresponds to a pressure of 0-913 



148-5 . 

 144 



= 0.885 



pound per square foot if we use the net area of the sail (148.5 square inches). 

 It is probably more correct to include the projected area of the boom, mast and 

 gaff and use the total area, which is 148.5 + 2.44 + 5.98 + .89 = 157.8 square 



T r *7 5^ 



inches. This gives for the maximum pressure 0.913 ~^ -^^^ = 0.833 pound per 



144 



