MACHINE PERFORMANCE CURVE 27 



_ 



d 1 



and ^=-oo5i^ LW ^S 



From these two equations we obtain 



,L/V 2 ,,T 

 f ^~ = ^ = ~~ 



.-. V = w L/W (V) 



-h V 



Also from the same two equations we obtain 

 , - J'L/D = L/V 2 = + ^ 



TT 



*' V 2 



.-. from equation (i) 



X L/iJ 



Equations (L/W), ( 7 ), (3), (^ (*'), (0, K), (V), and (P) are 

 in such a form that a tabular method can be applied to them, 

 though it does not work out so simply as in the cases of the First 

 and Second Methods (see Chapter XL). 



The values of L/D and k^ max used above are, of course, the 

 corrected values taken from the wing characteristic. 



The above equations having been solved tabularly, we have 

 values of V and P for values of X from *i to I -o : these values of 

 V and P are the data required for plotting the performance curve 

 for standard density air under the assumptions of the Third 

 Method. The extension of this method to the case of multi- 

 propeller machines presents no special difficulty. 



