NAVWEPS OO-EOT-80 
AIRPLANE PERFORMANCE 
cause the airplane to descend. However, as 
speed is reduced below the maximum level 
flight speed, parasite drag reduces and allows 
increased load factors and bank angles and 
reduced radius of turn, i.e., decreased parasite 
drag allows increased induced drag to accom- 
modate turns within the maximum thrust 
available. Thus, the considerations of con- 
stant altitude will increase the minimum turn 
radius above the aerodynamic limit and define 
a particular airspeed for minimum turn radius. 
Each of the three limiting factors (aero- 
dynamic, structural, and power) may combine 
to define the turning performance of an air- 
Pl ane. Generally, aerodynamic and structural 
limits predominate at low altitude while aero- 
dynamic and power limits predominate at high 
altitude. The knowledge of this turning per- 
formance is particularly necessary for effective 
operation of fighter and interceptor types of 
airplanes. 
TAKEOFF AND LANDING PERFORMANCE 
The majority of pilot caused airplane acci- 
dents occur during the takeoff and landing 
phase of flight. Because of this fact, the 
Naval Aviator must be familiar with all the 
many variables which influence the takeoff and 
landing performance of an airplane and must 
strive for exacting, professional techniques of 
operation during these phases of flight. 
Takeoff and landing performance is a con- 
dition of accelerated motion, For instance, 
during takeoff the airplane starts at zero veloc- 
ity and accelerates to the takeoff velocity to 
become airborne. During landing, the air- 
plane touches down at the landing speed and 
decelerates (or accelerates negatively) to the 
zero velocity of the stop. In fact, the landing 
performance could be considered as a takeoff 
in reverse for purposes of study. In either 
case, takeoff or landing, the airplane is ac- 
celerated between zero velocity and the takeoff 
or landing velocity. The important factors of 
takeoff or landing performance are: 
(1) The takeoff or landing velocity which 
will generally be a function of the stall 
speed or minimum flying speed, e.g., 15 per- 
cent above the stall speed. 
(2) The accclcration during the takeoff or 
landing roll. The acceleration experienced 
by any object varies directly with the un- 
balance of force and inversely as the mass of 
the object. 
(3) The takeoff or landing roll distance is 
a function of both the acceleration and 
velocity. 
In the actual case, the takeoff and landing dis- 
tance is related to velocity and acceleration in 
a .very complex fashion. The main source of 
the complexity is that the forces acting on the 
airplane during the takeoff or landing roll are 
“difficult to define wit,h simple relationships. 
Since the acceleration is a function of these 
forces, the acceleration is difficult to define in 
a simple fashion and it is a principal variable 
affecting distance. However, some simplifica- 
tion can be made to study the basic relatiomhip 
of acceleration, velocity, and distance While 
the acceleration is not necessarily constant or 
uniform throughout the takeoff or landing 
roll, the assumption of uniformly acceler- 
ated motion will facilitate study of the princi- 
pal variables. affecting takeoff and landing 
distance. 
From basic physics, the relationship of 
velocity, acceleration, and distance for uni- 
formly accelerated motion is defined by the 
following equation: 
s=g 
where 
S= acceleration distance, ft. 
V= final velocity, ft. per sec., after accel- 
erating uniformly from zero velocity 
a= acceleration, ft. per sec.* 
This equation ‘could relate the takeoff distance 
in terms of the takeoff velocity and acceleration 
when the airplane is accelerated uniformly 
from zero velocity to the final takeoff velocity. 
Also, this expression could relate the landing 
distance in terms of the landing velocity and 
deceleration when the airplane is accelerated 
(negatively) from the landing velocity to a