Prof. M. F. FitzGerald. 

 FIG. 2. 



5 



10 



for CD 20 



25 



2-5 2-6 



AbsciSSds W Foot: pounds per pound of Load carried. 

 CAB and CD are 



There are, no doubt, plenty of other reasons, but until experiments 

 can be made on planes or other surfaces flapped by pivoting on an 

 axis, numerical data for conditions of calculation agreeing more 

 nearly than those here used with conditions of fact, seem to be 

 wanting. 



Another point brought out is that #S cos has a minimum value 

 as well as W, but p has not. This means that the phase of the wing 

 motion, relatively to the twisting of the wing (on which the angle a 

 depends) is important, and if these are out of beat, so to speak, by 

 more than a certain amount, with a given frequency and stroke, the 

 flight cannot be maintained at all. The values of p which exceed 



