NAVWEPS OD-BOT-BO 
APPLICATION OF AERODYNAMICS 
TO SPECIFIC PROBLEMS OF FLYI’NG 
deficiency. It is most desirable that the power- 
plant be capable of effecting rapid changes in 
thrust to allow precise control of the airplane 
during approach. 
The type of approach path is an important 
factor since it affects the requirement of the 
flare, the touchdown rate of descent, and-to 
some extent-the ability to control the point 
of touchdown. Approach path A of figure 
6.4 depicts the steep, low power approach. 
Such a flight path generally involves a low 
power setting near idle conditions and a high 
rate of descent. Precise control of the air- 
plane is difficult and an excess airspeed usually 
results from an approach path similar to A. 
Waveoff may be difficult because of the re- 
quired engine acceleration and the high rate 
of descent. In addition, the steep approach 
path with high rate of descent requires con- 
siderable flare to reduce the rate of descent at 
touchdown. This extreme flare requirement 
will be di,fficult to execute with consistency 
and will generally result in great variation 
in the speed, rate of descent, and point of 
touchdown. 
Approach path C of figure 6.4 typifies the 
long, shallow approach with too small an 
inclination of the flight path.. Such a flight 
path requires a relatively high power setting 
and a deficiency of airspeed is a usual conse- 
quence. This extreme of an approach path 
is not desirable because it is difficult to control 
the point of touchdown and the low speed 
may allow the airplane to settle prematurely 
short of the intended landing touchdown. 
Some approach path between the extremes 
of A and C must be selected, e.g., flight path 
B. The desirable approach path must not 
incur excessive speed and rate of descent or 
require excessive flaring prior to touchdown. 
Also, some moderate power setting must be 
required which will allow accurate control 
of the flight path and provide suitable waveoff 
characteristics. The approach flight path 
cannot be too shallow for excessive power 
setting may be required and it may be difficult 
to judge and control the point of touchdown. 
The LSO, mirror landing system, and various 
approach lighting systems will aid the pilot 
in achieving the desired approach flight path. 
THE LANDING FLARE AND TOUCH- 
DOWN. The specific techniques of landing 
flare and touchdown will vary considerably 
between various types of airplanes. In fact, 
for certain types of airplanes, a flare from a 
properly executed approach may not be de- 
sirable because of the possibility of certain 
critical dynamic landing loads or because of 
the necessity for a certain standard of tech- 
nique when aerodynamic flare characteristics 
are critical. The landing speed should be the 
lowest practical speed above the stall or mini- 
mum control speed to reduce landing distances 
and arresting loads. Generally, the landing 
speed will be from 5 to 25 percent above the 
stall speed depending on the airplane type 
and the particular operation. 
The technique required for the landing will 
be determined in great part by the aerodynamic 
characteristics of the airplane. If the airplane 
characteristics are low wing loading, high LID, 
and relatively high lift curve slope, the airplane 
usually will have good landing flare charac- 
teristics. If the airplane characteristics are 
high wing loading, low L/D, and relatively low 
lift curve slope, the airplane may not possess 
desirable flare characteristics and landing tech- 
nique may require a minimum of flare to 
touchdown. These extremes are illustrated by 
the lift curves of figure 6.4. 
In preparation for the landing, several factors 
must be accounted for because of their effect 
on landing distance, landing loads, and arrest- 
ing loads. These factors are: 
(1) Landing gross weight must be con- 
sidered because of its effect on landing speed 
and landing loads. Since the landing is