8 Trans. Acad. Sci. of St. Louis. 



8. Numerical Applications of Formula [VIII]. 



P {IQVP , 22F\ 



^ 550 1 r 



+ 



15 



)-5^o(--V^¥) 



P means the resistance of still air to the motion of an air- 

 ship, moving V miles per hour, determined by experiment or 

 calculated by means of formula [IX]. 



The above six cases apply to six different air-ships. The 

 third is approximately that of Mr. Wellman, judging from the 

 data he has published. 



9. In the discussions of this paper, I have made no attempt 

 to approximate the loss of energy due to friction in the mechan- 

 ism, or to the friction of the air upon the blades; or that due to 

 defective design ; or to the impact of the propeller current upon 

 the frame-work, its contents and connections. 



Neither have I allowed for the energy spent fruitlessly upon 

 diverging currents of air. To prevent, or rather to utilize such 

 currents, I propose a short and thin enclosing cylinder for each 

 propeller, with a slightly-flaring forward end. 



I am preparing to experiment upon ' 'lifting" fans (with vertical 

 shafts) of various radii and various numbers of blades, and with 

 enclosing cylinders of various lengths.* 



* I learn from my friend, Dr. Octave Chanute, that experiments with 

 enclosing cylinders have been made in Europe, but I have no access to their 

 results. 



