text: To counter the undesirable inceractiuo be- 
  tween aerodynamic forces and wing torsional 
  deflections, the trailing edge ailerons may be 
  moved inboard to reduce the portion of the 
  twisting moments. Of 
  span subjected to 
  course, the short span, highly 
  tapered wing 
  planform is favorable for providing relatively 
  high stiffness. In addition, various configura- 
  tions of spoilers may be capabIe of producing 
  the required rolling performance without 
  the 
  development of large twisting moments. 
  
  STABILITY PROBLEMS 
  
  There are several general problems of flying 
  which involve certain principles of stability as 
  well as specific areas of longitudinal, direc- 
  tional and lateral stability. 
  Various condi- 
  tions of flight will exist in which certain 
  (or instability) are un- 
  problems of stability 
  avoidable for some reason or another. any 
  of the following 
  items deserve consideration 
  because of the possible unsafe condition of flight 
  and the contribution to an aircraft accident. 
  
  CRITICAL REQUIREMENTS, The critical 
  conditions for requiring adequate lateral con- 
  trol power may occur at either high speed or 
  low speed depending on the airplane configura- 
  tion and intended use. In transonic and super- 
  sonic flight, compressibility effects tend to 
  reduce the effectiveness of lateral control de- 
  vices to produce required roll helix angles. 
  These effects are most significant when com- 
  bined with a loss of control effectiveness due to 
  aeroelastic effects. Airplanes designed for 
  high speed flight must maintain suflicient 
  lateral control effectiveness at the design dive 
  speed and this is usually the predominating 
  requirement. 
  During  landing and takeoff, 