60 AEROPLANE PERFORMANCE CALCULATIONS 



The proper speed of flight to be maintained at that stage is 

 given by equation (V). 



The air mileage that has been covered up to that stage is 

 given by equation (;tr) with the help of equations (a) and (w). 



The time elapsed on the journey up to that stage is given by 

 equation (t) with the help of equations (a) and (b). We shall 

 need (f) if we wish to know the cruising conditions against a head 

 wind. 



