38 



EXPERIMENTS IN AERODYNAMICS. 



The third series of experiments made with the plane-dropper is designed 

 to investigate the effect of two sets of planes, one above the other. For this 

 purpose the planes and falling piece are so weighted that the previous ratio of 

 weight to surface is retained ; that is, in the previous case the weight is 1 pound 

 to 1 square foot of surface, and with the double set of planes the weight is 



Experiments with two sets of planes, one above the other. 

 Table VIII.— June 14, 1889. 



made 2 pounds to 2 square feet. The preceding experiments, made with the 

 single pair of 15 x 4 inch planes, were then repeated on June 14, with a double 

 pair of planes placed at distances of 2, 4, and 6 inches apart. The detailed 

 observations are given in Table VIII. The times of falling are plotted in Fig. 4. 

 The soaring speeds are plotted in Fig. 5, without attempting to smooth out the 



