THE COMPOiXEiNT PRESSURE RECORDER. 



61 



For the 12 X 12 inch square plane, and for the 30 x 4.8 inch and the 6 x 24 

 inch planes, which last two are the planes having the extremes of aspect, F (a) 

 has been computed from the above equation for W, and the results are plotted in 

 Fig. 10. In this computation TV is 500 grammes ; F is taken from the soaring 

 speed curves for successive values of a, and the adopted value of k,„, viz., 0.0080, 

 in metric units, is the mean value given by the normal planes in these experi- 

 ments. Comparing the resulting curve for the 12-inch square plane with the 

 curve derived from the experiments with the Resultant Pressure Recorder, we 



find the followino- values : 



TABLE XII. 



F (a), or the ratio of the pressure on an inclined plane one foot square, 

 to the pressure on the same normal jilane. 



The agreement between these values of F (a) derived from these two entirely 

 dissimilar methods of observation (dependent also, as it is, on the experimental 

 A^alue of k,,^) bespeaks the essential harmony of the entire system of results. If, 

 now, the curves of soaring speed have been determined for the 30 x 4.8 inch 

 and 6 x 24 inch planes with the same degree of accuracy as for the 12-inch square 

 plane, the computed values of F (a) for these planes has the same precision as 

 that for the 12-inch square plane. 



Looking at tlic curves, we find that for small angles the resultant normal 

 pressure is greatest in the 30x4.8 inch plane and least on the G x 24 inch i)lane; 

 but for angles above 30° this relation is reversed. 



The reversal in the relative positions of the curves of soaring speed at an 

 angle of inclination of about 30°, for differently shajied- planes, is now seen to 



