text: because of increase in the fuselage boundary 
  layer at the vertical tail location. The decay of 
  dir&ctional stability with angle of attack is 
  most significant for the low aspect ratjo air- 
  plane with sweepback since this configuration 
  requires such high angles of attack to achieve 
  high lifr coefficients. Such decay in directional 
  stability can have a profound effect on the re- 
  sponse of the airplane to adverse yaw and spin 
  characteristics. 