NAVWEPS 00-801-80  AIRPLANE PERFORMANCE  and it produces the minimum turn radius  within aerodynamic and structural limitations.  At speeds less than the maneuver speed, the  limit load factor is not available aerodynami-  cally and turning  performance is aerody-  namically limited.  At speeds greater than  the maneuver speed, CL-  and maximum  aerodynamic load factor are not available and  turning performance is structurally limited.  When the stall speed and limit load factor  are known for a particular configuration, the  maneuver speed is related by the following  expression:  define the maximum turning  performance.  The acrodynomic  limir describes the minimum  turn  radius available to the airplane when  operated at C,,,,.  When the airplane is at the  stall speed in level flight, all the lift is neces-  sary to sustain the aircraft in flight and none  is available to produce a steady turn.  Hence,  the turn radius at the stall speed is infinite.  As speed is increased  above the stall speed, the  airplane at C,,,  is able to develop lift greater  than weight and produce a finite turn radius.  For example, at a speed twice the stall speed,  the airplane at CL,,,,=  is able to develop a load  factor of four and utilize a bank angle of 75.5’  (cos 75.~~ = 0.25). Continued  increase in  speed increases  the load factor and bank angle  which is available aerodynamically but, be-  cause of the increase  in velocity and the basic  effect on turn radius, the turn radius approaches  an absolute minimum value. When C,,,  is  unaffected by velocity, the aerodynamic mini-  mum turn radius approaches this absolute  value which is a function of C,,,,,,,, W/S, and 6.  Actually, the one common denominator of  aerodynamic turning performance is the wing  level stall speed.  where  V,=maneuver speed, knots  V.=stall speed, knots  n limit = limit load factor  For example, an airplane with a limit load  factor of 4.0 would have a maneuver speed  which is twice the stall speed.  The aerodynamic limit  line of the first  illustration of figure 2.30 is typical of an air-  plane with a CL,  which is invariant with  speed. While this is applicable for the ma-  jority of subsonic airplanes, considerable  differ-  ence would be typical of the transonic or  supersonic airplane at altitude.  Compressi-  bility  effects and changes in longitudinal  control power may produce a maximum avail-  able CL which varies with velocity and an  aerodynamic turn radius which  is not an  absolute minimum at the maximum of velocity.  The aerodynamic limit of turn radius requires  that the increased velocity be utilized to pro-  duce increasing load factors and greater angles  of bank.  Obviously, very high speeds will  require very high load factors and the absolute  aerodynamic minimum turn radius will require  an infinite load factor.  Increasing speed  above  the stall speed will  eventually produce the  limit  load factor and continued increase in  speed above this point will require that load  factor and bank angle be limited to prevent  structural damage.  When the load factor and  bank angle are held constant at the structural  limit, the turn radius varies as the square of  the velocity and increases rapidly above the  aerodynamic limit.  The intersection of  ‘ the  aerodynamic limit and structural limit lines  is the  ‘ *maneuver speed.”  The maneuver  speed is the minimum speed necessary to  develop aerodynamically the limit load factor  The second  illustration of figure 2.30 describes  the constant altitude turning  performance  of an airplane. When an airplane is at high  ,altitude, the turning performance at the high  speed end of the flight speed range is more  usually thrust limited rather than structurally  limited.  In flight at constant altitude, the  thrust must equal the drag to maintain equilib-  rium and, thus, the constant altitude turn  radius is infinite at the maximum level flight  speed. Any bank or turn at maximum level  flight speed would incur additional drag and  180 