text: Operation in this region of high load factors 
  at .low gross weight may create the impression 
  the airplane has great excess strength 
  that 
  capability. This effect must be understood and 
  intelligently appreciated since it is not uncom- 
  mon to have a modern airplane configuration 
  with more than SO percent of its gross weight 
  as fuel. 
  
  GUST LOAD FACTORS. Gusts are asso- 
  ciated with the vertical and horizontal velocity 
  gradients in the atmosphere. A horizontal 
  gust produces a change in dynamic pressure on 
  the airplane but causes relatively small and 
  load factor. 
  unimportant changes in 
  The more important gusts are the vertical gusts 
  which cause changes in angle of attack. This 
  in figure 5.2. The vec- 
  process is illustrated 
  torial addition of the gust velocity to the air- 
  plane velocity causes the change in angle of 
  attack and change in lift. The change in angle 
  of attack at some flight condition causes a 
  change in the flight 
  load factor. The incre- 
  ment change in load factor due to the vertical 
  the following 
  gust can be determined from 
  equation: 
  
  flight 