effectively maneuver the aircraft. As a result, the increase  in aileron deflection causes an increase in adverse yaw. The  yaw is especially evident in aircraft with long wing spans.  Application of the rudder is used to counteract adverse  yaw. The amount of rudder control required is greatest at  low airspeeds, high angles of attack, and with large aileron  deflections. Like all control surfaces at lower airspeeds,  the vertical stabilizer/rudder becomes less effective and  magnifies the control problems associated with adverse yaw.  All turns are coordinated by use of ailerons, rudder, and  elevator. Applying aileron pressure is necessary to place  the aircraft in the desired angle of bank, while simultaneous  application of rudder pressure is necessary to counteract the  resultant adverse yaw. Additionally, because more lift is  required during a turn than during straight-and-level flight,  the angle of attack (AOA) must be increased by applying  elevator back pressure. The steeper the turn, the more elevator  back pressure that is needed.  As the desired angle of bank is established, aileron and  rudder pressures should be relaxed. This stops the angle of  bank from increasing, because the aileron and rudder control  surfaces are in a neutral and streamlined position. Elevator  back pressure should be held constant to maintain altitude.  The roll-out from a turn is similar to the roll-in, except the  flight controls are applied in the opposite direction. The  aileron and rudder are applied in the direction of the roll-out  or toward the high wing. As the angle of bank decreases,  the elevator back pressure should be relaxed as necessary  to maintain altitude.  In an attempt to reduce the effects of adverse yaw,  manufacturers have engineered four systems: differential  ailerons, frise-type ailerons, coupled ailerons and rudder,  and flaperons.  With differential ailerons, one aileron is raised a greater  distance than the other aileron and is lowered for a given  movement of the control wheel or control stick. This produces  an increase in drag on the descending wing. The greater drag  results from deflecting the up aileron on the descending wing  to a greater angle than the down aileron on the rising wing.  While adverse yaw is reduced, it is not eliminated completely.  [Figure 6-6]  With a frise-type aileron, when pressure is applied to the  control wheel, or control stick, the aileron that is being raised  pivots on an offset hinge. This projects the leading edge of  the aileron into the airflow and creates drag. It helps equalize  Figure 5-4. Frise-type ailerons. Figure 6-7.  Frise-type ailerons.  Differential Ailerons  Frise-Type Ailerons  the drag created by the lowered aileron on the opposite wing  and reduces adverse yaw.  [Figure 6-7]  The frise-type aileron also forms a slot so air flows smoothly  over the lowered aileron, making it more effective at high  angles of attack. Frise-type ailerons may also be designed  to function differentially. Like the differential aileron, the  frise-type aileron does not eliminate adverse yaw entirely.  Coordinated rudder application is still needed when ailerons  are applied.  Coupled ailerons and rudder are linked controls. This is  accomplished with rudder-aileron interconnect springs, which  help correct for aileron drag by automatically deflecting  the rudder at the same time the ailerons are deflected. For  Coupled Ailerons and Rudder  6-4  Figure 6-6 .  Differential ailerons.  Ail ero n  d e fl e c t e d u p  Aileron deflected down  Differential aileron  Lowered  Neutral  Raised  Drag 