The other point of importance on the Vg diagram is the  intersection of the negative limit load factor and line of  maximum negative lift capability. Any airspeed greater than  this provides a negative lift capability sufficient to damage  the aircraft; any airspeed less than this does not provide  negative lift capability sufficient to damage the aircraft from  excessive flight loads.  The limit airspeed (or redline speed) is a design reference point  for the aircraft—this aircraft is limited to 225 mph. If flight  is attempted beyond the limit airspeed, structural damage or  structural failure may result from a variety of phenomena.  The aircraft in flight is limited to a regime of airspeeds  and Gs that do not exceed the limit (or redline) speed, do  not exceed the limit load factor, and cannot exceed the  maximum lift capability. The aircraft must be operated  within this “envelope” to prevent structural damage and  ensure the anticipated service lift of the aircraft is obtained.  The pilot must appreciate the Vg diagram as describing the  allowable combination of airspeeds and load factors for  safe operation. Any maneuver, gust, or gust plus maneuver  outside the structural envelope can cause structural damage  and effectively shorten the service life of the aircraft.  The rate of turn (ROT) is the number of degrees (expressed in  degrees per second) of heading change that an aircraft makes.  The ROT can be determined by taking the constant of 1,091,  multiplying it by the tangent of any bank angle and dividing  that product by a given airspeed in knots as illustrated in  Figure 5-55.  If the airspeed is increased and the ROT desired  is to be constant, the angle of bank must be increased,  otherwise, the ROT decreases. Likewise, if the airspeed is  held constant, an aircraft’s ROT increases if the bank angle  is increased. The formula in  Figures 5-56  through  5-58  depicts the relationship between bank angle and airspeed as  they affect the ROT.  NOTE: All airspeed discussed in this section is true airspeed  (TAS).  Airspeed significantly effects an aircraft’s ROT. If airspeed is  increased, the ROT is reduced if using the same angle of bank  used at the lower speed. Therefore, if airspeed is increased  as illustrated in  Figure 5-57,  it can be inferred that the angle  of bank must be increased in order to achieve the same ROT  achieved in  Figure 5-58.  5-38  Rate of Turn  Figure 5-55.  Typical Vg diagram.  0  –1 2  –2 1  –3 6  5  4  7  3  20 40 60 80 100 120 140 160 180 200 220 240 Load factor  Indicated airspeed (mph)  Structural damage Caution range Structural failure Normal operating range A c c e $_{l}$e r a t e d s t a $_{l}$l  Structural Damage Normal stall speed Maneuvering speed Level flight at 1 G  Never exceed speed