36 AEROPLANE PERFORMANCE CALCULATIONS 



I96W 

 where a = - 



.. for our case where X = 1*0 we have that the landing speed 

 on glide is given by the equation 



V 



-Vs 



Now referring to page 34 we see that the corresponding 

 formula at an altitude is 



I96W 



though whether there is any useful meaning in the conception of 

 a "gliding landing speed at an altitude " is doubtful. 



Second Method. Following the Second Method of Chapter 

 IV., we have, from page 24 



V = ^L/W 



where 



X 

 I 9 6W 



^^ijmax 



t~c 



/ 



c 



^ 



and, in our case, X = I 'O. 



.*. the landing speed on glide is given by the equation 



v _ , 196W/ 



where k c is the centre of pressure coefficient corresponding to 

 X = I'O, i.e. to the stalling angle. 



In most machines there is a small difference between this 

 value of V and that calculated above : the difference is not great, 

 but if accuracy is required, this formula is the one to use. 



Again, for what it is worth, we have the " gliding landing 

 speed at an altitude " as given by the equation 



