text: thus, a constant dynamic pressure and equiva- 
  lent airspeed. As the airplane descends into 
  ground effect, the following. effects will 
  take 
  place: 
  
  (1) Because of the reduced induced angle 
  of attack and change in lift distribution, a 
  smaller wing angle of attack will be required 
  If a 
  to produce the same lift coefficient. 
  is maintained as 
  constant pitch attitude 
  ground effect is encountered, an increase in 
  lift coefficient will be incurred. 
  
  (2) The reduction in induced flow due to 
  ground effect causes a significant reduction 
  in induced drag but causes no direct effect on 
  parasite drag. As a result of the reduction 
  in induced drag, the thrust required at low 
  speeds will be reduced. 
  
  (3) The reduction in downwash due to 
  ground effect will produce a change in longi- 
  tudinal stability and trim. Generally, the 
  reduction in downwash at the horizontal 
  tail increases the contribution to static longi- 
  In addition, the reduction 
  tudinal stability. 
  of downwash at the tail usually requires 
  a greater up elevator to trim the airplane at 
  a specific lift coefficient. For the conven- 
  tional airplane configuration, encountering 
  ground effect will produce a nose-down 
  change in pitching moment. Of course, the 
  increase in stability and trim change associ- 
  ated with ground effect provide a critical re- 
  quirement of adequate longitudinal control 
  power for landing and takeoff. 