NAVWEPS DCI-ROT-RD  APPLICATION OF AERODYNAMICS  TO SPECIFIC PROBLEMS OF FLYl,NG  crease  in nose up attitude without the appro-  priate power change only controls the airplane  to a lower speed.  which increase with a decrease  in speed. Since  the increase in required power setting with  decreased  velocity is contrary to the normal  command of flight, the regime of flight speeds  between the speed for minimum  required  power setting and, the stall speed (or minimum  control speed) is termed the “region of re-  versed command. ”  In this regime of flight,  a decrease in airspeed  ‘ must be accompanied  by an increased  power setting in order to main-  tain steady flight.  Obviously, induced drag  or induced power required predominates in  this regime to produce the increased power  setting required with decreased  velocity. One  fact should be made clear about the region of  reversed command: flight in the “reversed”  region of command does not imply that a  decreased power setting will  bring about a  higher airspeed or an increased power setting  will produce a lower airspeed. To be sure,  the primary control of airspeed is not the  power setting.  Flight in the region of re-  versed command only implies that a higher  airspeed will repire a lower power setting and  a lower airspeed will require a higher power  setting to hold altitude.  The variation of power or thrust required  with velocity defines the power settings neces-  sary to maintain steady level flight at various  airspeeds. To simplify the situation, a gener-  ality could be,assumed that the airplane con-  figuration and. altitude define a variation of  power setting required (jet thrust required or  prop power required) versus velocity.  This  general variation of required power setting  versus velocity is illustrated by ’ the first graph  of figure 6.2.  This curve illustrates the fact  that at low speeds near the stall or minimum  control speed the power setting required for  steady level flight is quite high.  However,  at low speeds,  ant increase in speed reduces the  required power setting until some minimum  value is reached.at  the conditions for maximum  endurance. Increased speed beyond the con-  ditions for maximum endurance will  then  in&ease the power setting required for steady  level flight.  REGIONS OF NORMAL AND REVERSED  COMMAND.  This .typical variation of re-  quired power setting with  speed allows a  sort of terminology to be assigned to specific  regimes of velocity.  Speeds greater than the  speed for maximum endurance require increas-  ingly greater power settings to achieve steady,  level flight.  Since the normal command of  flight assumes a higher power setting will  achieve a greater speed, the regime of flight  speeds greater than the speed for minimum  required power setting is termed the “region  of normal command.”  Obviously, parasite  drag or parasite power predominates in this  regime to produce the increased power setting  required with increased velocity.  Of course,  the major items of airplane flight performance  take place in the region of normal command.  Flight speeds  below the sperd for maximum  endurance produce required power settings  Because of the variation of required power  setting throughout the range of flight speeds,  it is possible that one particular power setting  may be capable of achieving steady, level flight  at two different, airspeeds. As shown on the  first curve of figure 6.2, one given power setting  would meet the power requirements and allow  steady, level flight at both points 1 and 2. At  speeds  lower than point 2, a deficiency of power 1  would exist and a rate of descent would be in-  curred. Similarly, at speeds  greater than point  1, a deficiency of power would exist and the 1  airplane would descend. The speed range be-  tween points 1 and 2 would provide an excess  of power and climbing flight would be pro-  duccd  FEATURES OF FLIGHT IN THE NOR-  MAL AND REVERSED REGIONS OF COM-  MAND.  The majority of all airplane flight is  conducted in the region of normal command,  Revised January 1965  353  REGION 0~ REVERSED COMMAND 