rigidity is the consideration given to the inter- 
action of aerodynamic forces and deflections of 
the structure. The aircraft and its components 
must have sufficient stiffness to prevent or 
minimize aeroelastic influences in the normal 
flight range, Aileron reversal, divergence, 
flutter, and vibration should not occur in the 
range of flight speeds which will be normal 
operation for the aircraft. 
330