NAVWEPS WOT-BO  BASIC AERODYNAMICS  angle of attack indicator allows precision con-  trol of the airspeed.  The accomplished  insttu-  ment pilot is the devotee of “attitude”  flying  technique-his  creed being “attitude  plus  power equals performance.”  During a GCA  approach, the professional instrument pilot  controls airspeed with stick (angle of attack)  and rate of descent with power adjustment.  Maneuvering flight  and certain transient  conditions of flight tend to complicate the  relationship of angle of attack and airspeed.  However, the majority of flight and, certainly,  the most critical regime of flight (takeoff, ap-  proach, and landing), is conducted in essen-  tially steady flight condition.  Note that for the conditions of steady flight,  each airspeed  requites a specific  angle of attack  and lift coefficient. This fact provides a fun-  damental concept of flying technique: Angle  of attack  is tbs primary Control  of airspeed  in steady  flight.  Of course, the control stick or wheel  allows the pilot to control the angle of attack  and, thus, control the airspeed in steady flight.  In the same sense, the throttle controls the  output of the powerplant and allows the pilot  to control rate of climb and descent at various  airspeeds.  loo. .................  l.lm  1.30  20.00  110 ..................  ,826  1.24  15.P  17.0  ..................  ,694  1.04  12.7’  lY) ..................  .444  .61  8.20  200 ..................  230  .38  4.6’  MO. .................  ,111  .I7  2.10  4&l. .................  .c453  .o!J  1.10  30.7.  .................  ,040  .06  .T=  600 ..................  .028  .04  .5O  AIRFOIL LIFT CHARACTERISTICS.  Air-  foil section properties differ from wing or  airplane properties because  of the effect of the  planform.  Actually, the wing may have vati-  ous airfoil sections  from root to tip with taper,  twist, sweepback and local flow components  in a spanwise direction.  The resulting aeto-  dynamic properties of the wing are determined  by the action of each section along the span  and the three-dimensional flow.  Airfoil sec-  tion properties are derived from the basic shape  or profile in two-dimensional flow and the force  coefficients  are given a notation of lower case  letters. For example, a wing or airplane lift  coefficient is C, while an airfoil section lift  coefficient is termed cr. Also, wing angle of  attack is Q while section angle of attack is  differentiated by the use of 01~. The study of  section properties allows an objective consider-  ation of the effects  of camber, thickness, etc.  The teal believers of these concepts ate pro-  fessional instrument pilots, LSO ’ s, and glider  pilots.. The glider pilot (or flameout enthusi-  ast) has no recourse  but to control airspeed by  angle of attack and accept whatever rate of  descent is incurred at the various airspeeds.  The LSO must become  quite proficient at judg-  ing the flight path and angle of attack of the  airplane in the pattern.  The more complete  visual reference field available to the LSO  allows him to judge the angle of attack of  the airplane mote accurately than the pilot.  When the airplane approaches the LSO, the  precise judgment of airspeed is by the angle  of attack rather than the rate of closure. If  the LSO sees  the airplane on the desired flight  path but with too low an angle of attack, the  airspeed is too high; if the angle of attack is  too high, the airspeed is too low and the ait-  plane is approaching the stall.  The mirror  landing system  coupled with an angle of attack  indicator is an obvious refinement.  The mit-  tot indicates the desired flight path and the  The lift characteristics of five illustrative  airfoil sections are shown in figure 1.12.  The  section lift coe&icient, c,, is plotted versus  section angle of attack, olO,  for five standard  NACA airfoil profiles. One characteristic  fea-  ture of all airfoil sections is that the slope of  the various lift curves is essentially the same.  At low lift coefhcients,  the section lift coeffi-  cient increases approximately 0.1 for each  degree increase in angle of attack. For each  of the airfoils shown, a S’ change in angle of  27 