NAVWEPS oo-80mo  AIRPLANE PERFORMANCE  the airplane were at a 60’ bank and lift were  not provided to produce the exact load factor  of 2.0, the aircraft would be accelerating in the  vertical direction as well as the horizontal di-  rection and the turn would not be steady.  Also, any sideforce on the aircraft due to  sideslip, etc., would place the resultant aero-  dynamic force out of the plane of symmetry  perpendicular to the lateral axis and the turn  would not be coordinated.  would be to provide the endurance  thrust with  some engine(s) shut down and the remaining  engine(s) operating at a more efficient power  output.  This technique would cause a mmi-  mum loss of endurance  if at low altitude.  The  feasibility of such a procedure is dependent  on many operational factors.  In all cases, the airplane should be in the  cleanest  possible external configuration because  the specific endurance is directly proportional  to the (L/D).  As a consequence of the increase lift re-  quired to produce the steady turn in a bank,  ’ ihe induced drag is increased above that in-  curred by steady, wing level, lift-equal-weight  flight.  In a sense, the increased lift required  in a steady turn will increase  the total drag or  power required in the same manner as increased  gross weight in level flight.  The curves of  figure 2.28 illustrate the general effect of turn-  ing flight on the total thrust and power re-  quired.  Of course, the change in thrust re-  quired at any given speed is due to the change  in induced drag and the magnitude of change  depends on the value of induced drag in level  flight and the angle of bank in .turning flight.  Since the induced drag generally varies as the  square of C,,  the following data provide an  illustration of the effect of various degrees of  bank :  When the airplane is ’ in  turning flight, the  airplane is not in static equilibrium for there  must be developed the unbalance of force to  produce the acceleration of the turn.  During  a steady coordinated turn, the lift is inclined  to produce a horizontal component of force to  equal the centrifugal force of the turn.  In  addition, the steady turn is achieved by pro-  ducing a vertical component of lift which is  equal to the weight of the airplane. Figure  2.28 illustrates the forces which act on the  airplane in a steady, coordinated turn.  MANEUVERING PERFORMANCE ,...s’  For the case of the steady, coordinatedturn,  the vertical component oft lift must equal the  weight of the aircraft so that there will be no  acceleration in the vertical direction.  This  requirement leads to the following relation-  ship:  L  *=-  W  1  BE--  cos q5  n=sec $6  where  rz= load factor or “G”  L=lift,  lbs.  W= weight, Ibs.  += bank angle, degrees  (phi)  From this relationship it is apparent that the  steady, coordinated turn requires specific  values  of load factor, n, at various angles of bank, 6.  For example, a bank angle of 60’ requires a  load factor of 2.0 (cos 60 ’ =0.5  or set 60 ’ =2.0)  to provide the steady, coordinated turn.  If  Since the, induced drag predominates at low  speeds, steep turns at low speeds can produce  significant increases  in thrust or power required  to maintain altitude.  Thus, steep turns must  be avoided after takeoff, during approach, and  especially during a critical power situation  from failure or malfunction of a powerplant.  The greatly increased induced drag is just as  176  Load factor, Pcrccnt  incrcaw in  n  induced drag from  lcvcl flight 