NAVWEPS 00-BOT-80 
APPLICATION OF AERODYNAMKS 
TO SPECIFIC PROBLEMS OF FLYl,NG 
A particular advantage of an angle of attack 
indicator is that the indicator is not directly 
affected by gross weight, bank angle, load 
factor, velocity, or density altitude. The 
typical lift curve of figure 6.3 illustrates the 
variation of lift coefficient, C,, with angle of 
attack. a. When a particular aerodynamic 
configuration is in subsonic flight, each angle 
of attack produces a particular value of lift 
coefficient. Of course, a point of special 
interest on the lift curve is the maximum lift 
coefficient, C,,,,. Angles of attack greater 
than that for C,,,, produce a decrease in lift 
coefficient and constitute the stalled condition 
of flight. Since Cz,., occurs at a particular 
angle of attack, any device to provide a stall 
warning should be predicated on the function 
of this critical angle of, attack. Under these 
conditions, stall of the airplane may take place 
at various airspeeds depending on gross weight, 
load factor, etc., but always the same angle of 
attack. 
In order to reduce takeoff and landing dis- 
tances and minimize arresting loads, takeoff 
and landing wil! be accomplished at minimum 
practical speeds. The takeoff and landing 
speeds inust provide suficient margin above 
the stall speed (or minimum control speed) 
and are usually specified at some fixed per- 
centages of the stall speed. As such, takeoff, 
approach, and landing will be accomplished 
at specific values of lift coefficient and, thus, 
particular angles of attack. For example, 
assume that point A on the lift curve is defined 
as the proper aerodynamic condition for the 
landing approach. This condition exists as 
a particular lift coefficient and angle of attack 
for a specific aerodynamic configuration. 
When the airplane is flown in a steady flight 
path at the prescribed angle of attack, the 
resulting airspeed will be appropriate for the 
airplane gross weight. Any variation in gross 
weight will Simply alter the airspeed necessary 
to provide suificient lift. The use of an angle 
of attack indicator to maintain the recom- 
mended angle of attack will insure that the 
airplane is operated at the proper approach 
speed-not too low or too high an airspeed. 
In addition to the tise of the angle of attack 
indicator during approach and landing, the 
instrument may te used as a principal reference 
during takeoff. The use of the angle of attack 
indicator to assume the proper takeoff angle 
of attack will prevent both over-rotation and 
excess takeoff speed. Also, the angle of at- 
tack indicator may be applicable to assist in 
control of the airplane for conditions of range, 
endurance, maneuvers, etc. 
THE MIRROR LANDING SYSTEM. A 
well planned, stabilized approach is a funda- 
mental requirement for a good landing. How- 
ever, one of the more difficult problems of 
perception and orientation is the positioning 
of the airplane along a proper flight path dur- 
ing approach to landing. While various de- 
vices are possible, the most successful form of 
glide path indicator applicable to both field 
and shipboard operations is the mirror landing 
system. The function of the mirror landing 
system is to provide the pilot with an accurate 
visual reference for a selected flight path which 
has the desired inclination and point of touch- 
down. Utilization of the mirror system will 
allow the pilot to position the airplane along 
the desired glide path and touch down at the 
desired point. When the proper glide path 
inclination is set, the pilot can be assured that 
the rate of descent will not be excessive and 
a foundation is established for a successful 
landing. 
The combination of the angle of attack in- 
dicator and the mirror landing system can 
provide an excellent referetice for a landing 
technique. The use of the angle of attack 
indicator will provide the airplane with the 
proper airspeed while the mirror system refer-