u6 



CHAPTER XII. 



AIR PERFORMANCE. 



I. GLIDING FLIGHT. 



Landing Speed on Glide. This has no particular meaning at 

 an altitude, but the figure is included for the sake of complete- 

 ness. The First Method is less accurate, but not much so, than 

 the Second. 



Definitions. W is the total weight of the machine in pounds. 



S is the total wing area in square feet. 



k^jnax is the corrected value already found under the heading 

 of wing characteristics. 



cr is plotted against altitude on page 104. 



/ is the distance in feet from the e.g. of the machine to the 

 c.p. of the tail plane (or front spar of the tail plane will do). 



/' is the distance in feet from the leading edge of the equi^ 

 valent chord (-55 up the gap) to the c.p. of the tail plane. 



c is the wing chord in feet. 



k c is the uncorrected value of the centre of pressure coefficient 

 in this case being limited to refer to its value when X = I -o. 



First Method. In standard density air 



y. ^ 



S 

 and at an altitude * 



V = 



Second Method. In standard density air 



-Vs 



I96W/ 



* See footnote to page 117. 



