no AEROPLANE PERFORMANCE CALCULATIONS 



is subject to the action of the slip stream. S' is obtained by 

 reducing S in the ratio of the sum of the lengths of such parts 

 of the top and bottom leading edges as fall within the propeller 

 circle in front view to the sum of the lengths of the top and 

 bottom leading edges for the whole machine in front view. 



c is the chord of the wing in feet. 



/ is the horizontal distance in feet from the e.g. of the 

 machine to the c.p. of the tail plane.* 



/' is the horizontal distance in feet from the leading edge of 

 the equivalent chord f to the c.p. of the tail plane. 



d is the diameter of the propeller in inches. A reasonable 

 trial value (if not the final value) of this has already been found 

 by the method of Chapter X., page 98 : this value is to be used 

 for the present calculation. 



R! and R 2 are the body resistances in pounds at 100 miles 

 per hour already found by the method of Chapter VIII., page 

 77, R! corresponding to parts in the slip stream and R 2 corre- 

 sponding to the rest of the machine. 



k^ max and L/D are corrected values for values of X from 

 I to i'O and have already been found by the method of 

 Chapter IX., page 85, where they will be found in the last 

 column of the first table. 



k c is the centre of pressure coefficient, to which no corrections 

 need be applie.d. 



V is the speed of the machine in miles per hour in standard 

 density air. 



P is the effective horse-power required to maintain horizontal 

 flight at V miles per hour in standard density air. 



Now write down the numerical values of W, S, S', Lmax , 

 Rj, R 2 , c, /, /', and d. 



Then work out and write down the numerical values of 







,/ 



W / /' 



a = -j-r; -- , 7 = - ana o = -. 



ad + be c c 



Then construct a table in the following form : 



* It is sufficiently accurate for our purpose to assume that the c.p. of the tail 

 plane is at the front tail plane spar. 



fThe leading edge of the equivalent chord is on the line joining the top and 

 bottom leading edges of the biplane, and at a distance above the leading edge of the 

 bottom plane of '55 of the gap. 



