NAVWEPS OO-80T-80  OPERATING STRENGTH LIMITATIONS  CHANGE IN LIFT  AIRPLANE VELOCITY, V  GUST  VELOCITY  RESULTANT VELOCITY  KU  figure 5.2. Effect of Vertical Gust  of the airplane and the gradient of the gust.  A gust factor, K (usually on the order of 0.6),  reduces  the actual gust to the equivalent sharp  edged gust velocity, KU.  e.g., if in level flight before encountering the  gust, a final load factor of 1.0+1.61=2.61  would result. As a general requirement all  airplanes must be capable of withstanding an  approximate effective f30  ft. per sec. gust  when at maximum level flight speed for normal  rated power. Such a gust intensity has rela-  tively low frequency of occurrence  in ordinary  flying operations.  The properties of the airplane exert a power-  ful influence on the gust increment. The lift  curve slope, m, relates the sensitivity of the  airplane to changes in angle of attack.  An  aircraft with  a straight, high aspect ratio  wing would have a high lift curve slope and  would be quite sensitive to gusts. On the  other hand, the low aspect ratio, swept wing  airplane has a low lift curve slope and is com-  paratively less sensitive to turbulence. The  apparent effect of wing loading, W/S, is at  times misleading and is best understood by  considering a particular airplane encountering  a fixed gust condition at various gross weights.  If the airplane encounters the gust at lower  than ordinary gross weight, the accelerations  The equation for gust load increment pro-  vides a basis for appreciating many of the  variables of flight.  The gust load increment  varies directly with  the equivalent sharp  edged gust velocity, KU, since this factor  effects the change in angle of attack.’  The  highest reasonable gust velocity that may be  anticipated is an actual vertical velocity, U,  of 50 ft. per sec. This value is tempered by  the fact that the airplane does not effectively  encounter the full effect because  of the response 