text: where 
  
  Dil= 
  
  induced drag corresponding to some orig- 
  inal speed, Vi 
  
  Di,= induced drag corresponding to some new 
  
  speed, Vs 
  
  (and L, S, AR, ,J are constant) 
  
  Such an effect would imply that a given air- 
  plane in steady flight would incur one-fourth 
  as great an induced drag at twice as great a 
  speed or four times as great an induced drag at 
  half the original speed. This variation may 
  be illustrated by assuming that an airplane in 
  steady level flight is slowed from 300 to 150 
  knots. The dynamic pressure at 1% knots is 
  one-fourth the dynamic pressure at 300 knots 
  and the wing must deflect the airstream four 
  times as greatly to create the same lift. 
  The 
  force is then slanted aft four times 
  same lift 
  as greatly and the induced drag is four times 
  as great. 
  
  The expressed variation of induced drag with 
  speed points out that induced drag will be of 